LOW TEMPERATURE IMPACT TESTING OF WELD ED STRUCTURAL WROUGHT IRON by ZACHARY ROGERS B.S., Colorado State University, F ort Collins 2008 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment o f the requirements for the degree of Master of Science Civil Engineering 2014
ii This thesis for the Master of Science degree by Zachary Rogers has been approved for Civil Engineering Program b y Frederick R. Rutz Chair Kevin L. Rens Cheng Yu Li May 2 2014
iii Rogers, Zachary (M.S. Civil Engineering) Low Temperature Impact Testing o f Double Bevel Full Penetration Groove Welds for the Repair of Historic Structural Wrought Iron Thesis directed by Assistant Professor Frederick R. Rutz ABSTRACT Durin g the second half of the 19 th century, structural wrought iron was commonly used in construction of bridges and other structures Today, t hese remaining structures are still actively in use and may fall under the protection of historic preservation agenci es. Continued use and protection leads to the need for inspection, maintenance, and repair of the wrought iron within these structures. Welding can be useful to achieve the appropriate repair rehabilitation, or replacement of wrought iron members. There is currently very little published on modern welding techniques for historic wrought iron. There is also no pre qualified method for this welding. The demand for welding in the repair of historic structural wrought iron has led to a line of research inv estigating shielded metal arc welding (SMAW) of historic wrought iron at the University of Colorado Denver This prior research selected the weld type and other weld specifications to try and achieve a recognized specific welding procedure using modern SM AW technology and technique s This thesis continues investigating SMAW of historic wrought iron. Specifically, this thesis addresses the toughness of these welds from analysis of the data collected from performing Charpy V Notch (CVN) Impact Tests. Tempe rature was varied to observe the material response of the welds at low temperature The wrought iron used in testing was from a historic vehicle bridge in Minnesota, USA. This area, and many other areas with wrought iron structures, can experience sustai ned or fluctuating temperatures far below freezing. Investigating the toughness of welds in historic wrought iron at these temperatures is necessary to fully understand material
iv responses of the existing structures in need of maintenance and repair. It w as shown that welded wrought iron is tougher and more ductile than non welded wrought iron. In regards to toughness, welding is an acceptable repair method. Information on wrought iron, low temperature failure, welding, and impact testing is also present ed in an effort to provide those writing codes and standards, designing, or working with historic structural wrought iron more data, analysis, and research based recommendations. The form and content of this abstract are approved. I recommended its public ation. Approved: Frederick R. Rutz
v ACKNOWLEDGEMENTS This master thesis would not have been possible without the support, guidance, and passion for historical preservation of Dr. Frederick R. Rutz. His continual desire to further research on these topi cs has led to a great amount of learning, discovery, and innovation Dr. Rutz is responsible for finding, acquiring, and transporting all of the wrought iron used for testing. He has also inspired many engineers and non engineers alike through his teachin g and counseling to further their education and put the legs behind continuing a forward march of structural engineering research. Thank you for everything. Thank you to Preeda Chomsrimake and Joel Watters for their hard work in their research and theses allowing the writer a solid foundation to continue research on this topic. Those that helped to provide materials and specimens for testing are so greatly appreciated. Specifically, m any thanks to Bill Campbell and his students at Western Colorado Commu nity College for putting in the many hours to provide the welds needed to perform testing. Also many thanks to Jac Corless for machining hundreds of wrought iron test specimens. Finally, thanks to Ryan Thomas a t Emily Griffith Technical Colle ge for offe ring his expert advice, technical knowledge and providing welding training so this researcher could develop a deeper understanding of welding itself Thank you to the Mechanical Engineering Department at the University of Colorado Denver for allowing a co uple of structural engineers the use of their measurements laboratory and equipment. Thank you to the Civil Engineering Department at the University of Colorado Denver for turning this researcher from a mathematician into a future life long engineer.
vi TA BLE OF CONTENTS CHAPTER I. INTRODUCTION Purpose of Research Scope of Research Goals for Research II. HISTORY AND LITERATURE REVIEW Properties of Wrought Iron History of Wrought Iron Manufacture of Wrought Iron Applications of Structural Wrought Iron Brittle F ailure Wrought Iron Used in Testing Repair of Structural Wrought Iron III. SHIELDED METAL ARC WELDING General Information Weld Qualifications Procedure for Wrought Iron Basis for Research Specifications Welding Performed for Testing IV. CHARPY V NOTCH IMPACT TESTI NG History and Background Preparation of Specimens Testing Procedure V. RESULTS AND ANALYSIS Testing Report 1 1 2 2 4 4 7 7 8 10 12 13 15 15 1 7 18 18 1 8 23 23 27 2 9 3 4 3 4
vii General Testing Notes Limitations CVN Test Results Data Analysis VI. SUMMARY AND RECOMMEND ATIONS Summary of Testing and Results Recommendations Continued and Future Research REFERENCES APPENDIX A. Specimen Drawings and Measurement Tables B. CVN Test Plots and Tables C. CVN Testing Photographs D. Testing Machine Documentation E. Weld Quality Assurance Sheets 34 36 37 40 44 44 4 4 45 46 48 48 52 6 2 93 98
viii TABLES TABLE 2.1: Typical Chemical Make Up of Wrought Iron 2.2: History of Brittle Fractures 5.1 : Initial CVN T est R esults 5.2: Average Results and Temperature Goal 5.3: Final CVN Test Results 5.4: Weld ed vs. Non welded Average Energies 5.5: Change in Energy over Change in Temperature 5.6: Qualitative CVN Test Results A.1: Initial CVN Test Dimensions A.2: Final CVN Test Dimensions A.3: Cooling Bath Quantities B.1: Charpy Impact Test Results (Bowman ) 6 11 37 38 39 40 41 43 49 50 51 59
ix FIGURES FIGURE 2.1: 100x magnification photomicrograph of wrought iron 2. 2 : Basic d ifferences b etween w rought i ron, s teel, and cast i ron 2.3 : Front page of p amphlet from Wrought Iron Bridge Co. Canton OH 2. 4: Member layout of Bridge #5721 2.5: Bridge #5721 in Koochiching County 2.6: Silverdale Bridge over Manning Ave (CR 15) in Washington County 3.1: Diagram of SMAW 3.2: Arc welding circuits 3.3: Double bevel full penetration groove weld 3.4: Drawing of weld coupon 3.5: Weld coupons being measured and marked at WCCC 3.6: Drawing of planned weld coupons from wrought iron bridge member 4.1: Augustine Georges Albert Charpy and the cover of the original paper tests 4.2: Welded wrought iron specimens with brittle (above) and ductile (below) fracture planes. 4.3: Tinius Olsen Model 55 Charpy Impact Tester 4.4: Charpy (Simple Beam) Impact Test Specimens, Type A. 4.5: Machined specimen. Note: Weld defects 4.6 : Machined specimen after width adjustment. 4.7: Charpy Simple Beam Impact Test. 4.8: A specimen in the testing machine. 4.9: Cooling bath equipment and chemicals. 4.10: Stand used to keep specimens off the bottom of the bath. 4 5 10 12 13 13 15 16 1 9 20 20 2 2 23 25 26 27 28 29 31 3 2 32 3 3
x 4.11 : Specimen position markings in the testing machine. 5.1: Specimen dimension al notation A.1: Charpy (Simple Beam) Impact Test Specimens, Type A. A.2: Specimen dimensional notation B.1: Welded Wrought Iron CVN Test Results B.2: Welded Wrought Iron Adjusted CVN Test Results B.3: Non welded Wrought Iron CVN Test Results B.4: CVN Test Results B.5: Adjusted CVN Test Results B.6: Adjusted CVN Average Test Results B.7: Charpy Impact Testing Results (Bowman) B.8: Adjusted CVN Comparative Average Test Results B.9: C.1: Specimen M1 4.4, tested at 58.2 F C.2: Specimen M1 4.5, tested at 57.1 F C.3: Specimen M1 4.6, tested at 54.7 F C.4: Specimen M1 6.1, tested at 38 .1 F C.5: Specimen M1 6.2, tested at 36.2 F C.6: Specimen M1 6.3, tested at 34.1 F C.7: Specimen M1 6.4, tested at 16.7 F C.8: Specimen M1 6.5, tested at 14.9 F C.9: Specimen M1 6.6, tested at 14.0 F C.10: Specimen M1 7.1 tested at 3.9 F C.11: Specimen M1 7.2, tested at 4.2 F C.12: Spe cimen M1 7.3, tested at 5.6 F C.13: Specimen M1 7.4 tested at 23.9 F 33 36 48 48 52 53 54 55 56 57 58 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74
xi C.14: Specimen M1 7.5, tested at 24.0 F C.15: Specimen M1 7.6, tested at 25. 9 F C.16: Specimen M1 14.1, tested at 44.0 F C.17: Specimen M1 14.2, tested at 44.8 F C.18: Specimen M1 14.3, tested at 45.0 F C.19: Specimen M1 14.4, tested at 63.2 F C.20: Specimen M1 14.5, tested at 64.4 F C.21: Specimen M1 14.6, tested at 66.6 F C.22: Specimen M1 4.1, teste d at 76.7 F C.23: Specimen M1 4.2, tested at 76.5 F C.24: Specimen M1 4.3, tested at 76.4 F C.25: Specimen M3. 3 tested at 56.3 F C.26: Specimen M3.4 tested at 54.8 F C.27: Specimen M3.5 tested at 53.2 F C.28: Specimen M3.6 tested at 9.5 F C.2 9: Specimen M3.7 tested at 7.4 F C.30: Specimen M3.8 tested at 10.5 F C.31: Specimen M3.1, tested at 74.4 F C.32: Specimen M3.2, tested at 74.1 F D.1: Testing machine documentation, page 1 D.2: Testing machine documentation, page 2 D.3: Testing machine documentation, page 3 D.4: Testing machine documentation, page 4 D.5: Testing machine documentation, page 5 E.1: M1 1 QA Sheet E.2: M1 4 QA Sheet 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100
xii E.3: M1 5 QA Sheet E.4: M1 6 QA Sheet E.5: M1 7 QA Sheet E.6: M1 8 QA Sheet E.7: M1 9 QA Sheet E.8: M1 11 QA Sheet E.9: M1 12 QA Sheet E.10: M1 13 QA Sheet E.11: M1 14 QA Sheet 100 10 1 10 1 10 2 10 2 10 3 10 3 10 4 10 4
xiii ABBREVIATIONS AC Alternating current A ISC American Institute of Steel Construction ASTM American Society for Testing Materials AWS American Welding Society CC Constant current CVN Charpy V Notch DBTT Ductile brittle transition temperature DC Direct current DCEN Direct current e lectrode negative DCEP Direct current electrode positive DOT Department of Transportation HAZ Heat affected zone MnDOT Minnesota Department of Transportation NDT Nil ductility temperature PQR Procedure Qualification Record SMAW Shielded Metal Arc Welding UCD University of Colorado Denver WCCC Western Colorado Community College WPS Welding Procedure Specification
1 CHAPTER I INTRODUCTION Purpose of Research Currently, economics, sustainability, and historical preservation are all importa nt aspects of structural engineering. While wrought iron is no longer used as a structural material today, during the second half of the 19 th century, it was prevalent. Particularly in bridges, structural wrought iron was common. Over 100 years later, h istorical bridges are still in use today. Whether used as rail, vehicle, or pedestrian bridges, continued inspection, maintenance, and repair are required. long term continued use pro motes sustainability and good engineering economy Infrastructure budgets are in a constant state of fluctuation making replacement and new construction difficult for many federal, state, and local departments of transportation (DOT s ) Historical preserv ation also plays an important role in emphasizing maintenance and repair of wrought iron bridges as a glimpse into the past of infrastructure and transport ation engineering in the United States. Engineers and construction contractors need access to modern repair and rehabilitation methods for existing wrought iron structures. Modern welding techniques commonly used on steel and other structural materials, can also be used on historic wrought iron. There is currently a lack of documented or standardized w elding procedures for governing DOTs and municipalities to adopt into code. The American Welding Society (AWS) publishes the majority of pre qualified welding procedure s, but have yet to publish repair methods using modern welding techniques on historic s tructural wrought iron. A procedure qualification record (PQR) leads to a welding procedure specification (WPS) ; processes laid out by the AWS. This thesis with its supporting research and testing has been designed to further the development of qualified welding procedures for wrought iron repair and rehabilitation in historic structures.
2 Scope of Research Like many other industrial technologies widely used today, welding presents a large variety of types and techniques for metal work For this the sis a specific type of welding joint, and welding material was selected to focus this research under resource, budget, and timeline limitation Based on the prior research of other University of Colorado Denver (UCD) structura l engineering graduate student s Preeda Chomsrimake and Joel Watters this thesis focused on double bevel full penetration groove welds on butt joints performed by the process of shielded metal arc welding (SMAW). The electrode used for this thesis was E7018. Pre heat temperature, gro ove angle, and other joint parameters are described in Chapter III. There were no variables in the welds performed on the wrought iron so that all testing would be representative of the chosen welding technique, also described in Chapter III. The testing performed for this thesis was the Charpy V Notch (CVN) impact test. This test ing as described in Chapter IV, is used to determine material toughness To begin to understand how welded wrought iron performs under different temperatures, the testing vari able was the temperature of the impact test specimens. SMAW performed on historic structural wrought iron was impact tested and the data and results were analyzed. This analysis can be found in Chapter V. From the research performed in completion of thi s thesis, recommendations for whether SMAW should be used for repair ing structural wrought iron and supporting data from this research can be found in Chapter s V and VI. Goals for Research The goal of this thesis is to continue research and contribute ne w data on modern welding procedures for historic structural wrought iron. Specifically, through the analysis of test results from the CVN i mpact test The toughness of welded wrought iron specimens will be com pared to the same solid wrought iron non wel ded specimens The CVN test is frequently used for AWS PQRs from testing structural steel. Understanding material toughness and response under
3 different temperatures will allow welded wrought iron to be compared to other modern materials that are commonly welded, such as steel. Demonstrating that welding this historic structural material will not reduce ductility or toughness will allow structures wi th wrought iron that has been repaired to be deemed to have restored or maintained structural integrity T his will be helpful for engineers, DOTs, and preservationists alike in dealing with wrought iron in the future O nce a good understanding of how historic wrought iron performs once welded, institutions such as AWS, American Institute of Steel Construction (AISC), and other code publishers and developers can include historic structural wrought iron.
4 CHAPTER II HISTORY AND LITERATURE REVIEW Properties of Wrought Iron Wrought iron was officially defined by the American Society for Testing Materials (ASTM) in 1930 as: A ferrous material aggregated from a solidifying mass of pasty particles of highly refined metallic iron, with which, without subsequent fusion, is incorporated in a minutely and uniformly distributed quantity of slag (Bowman 2004) Literal iron and iron silicate. Iron silicate, called slag, is a glasslike and siliceous material forming pockets in the iron as it is mechanically mixed during manufacturing. As seen in Figure 2.1 t his siliceous slag is a unique characteristic of wrought iron. During refinement, the wrought iron becomes a hot pasty material. While it is being worked, rolled, or forged the slag is dispersed, elongated, and squeezed within the iron This leads to the slag being di stributed throughout the Figure 2.1 100x magnification photomicrograph of wrought iron (A ston 1939)
5 iron in fibrous stringers, making wrought iron both fibrous and crystalline in nature. The slag lubricates and reduces internal friction as it melds with the iron aiding in deformability and resis tance to fatigue The slag content in wrought iron typically varies from 1% to 3% by weight, depending upon the amount of rolling necessary to produce the finished section (Aston 193 9) As w rought iron is typically rolled for structural purposes, the sla g stringers run in the direction of rolling. This makes structural wrought iron anisotropic and considerably stronger in the direction of rolling. Unlike other iron ore based alloys like cast iron or steel, wrought has very little carbon content. Figure 2.2 compares typical carbon contents of these materials. Chemical analysis of wrought iron shows that there is typically less than 0.15% carbon found in the material (Tiemann 1919) The low carbon content leads to wrought iron being ductile, malleable, and resistant to corrosion and fatigue. It can be worked hot or cold and the low carbon content also makes it easier to weld using fusion processes. Wrought iron is also considered tough and strong, though not in comparison to modern steel. As mentioned a b ove, wrought iron is resistant to corrosion. This is mainly due the non 0 1 2 3 4 5 6 7 Percent Carbon (%) Cast Iron Steel Wrought Iron Figure 2.2: The basic difference in wrought iron, steel, and cast iron is their percent carbon content. ( Adapted from Brandt 2005)
6 locks with the oxide from rust or mill scale preventing flaking and further corrosion. T he resistance to fatigue is also due to the slag. The slag fibers apparently serve to minimize stress concentration and deflect the path of slip planes that develop in a metal under the influence of conditions which ordinarily would result i n fatigue failu re (Aston 1939) This leads to fatigue problems such as notch effects and over stress having a minimal effect on wrought iron. Wrought iron largely exhibits the properties of pure iron, due to iron being the primary component. The typical chemical make up of wrought iron can be found in Table 2.1. The high silicon, high phosphorus, and low carbon content are the major chemical differences between Table 2.1: T he t ypical chemical make up of wrought iron (Adapted from Brandt 2005) Element Percentage Composition Iron >99.6% Carbon 0.06% 0.08% Silicon 0.10% 0.16% Manganese 0.02% 0.05% Sulfur 0.01% Phosphorus 0.06% 0.07% wrought iron and steel. Any large differences from the values shown in the table are indications of improp er or inconsistent manufactur ing Too high phosphorus content can lead to low ductility and too high carbon content implies that the iron ore was possibly mixed with cast iron or steel. In order to positively determine the chemical composition of wrought iron, a laboratory chemical analysis must be performed. In lieu of this, a spark test or other material tests can be performed and compared to the results of known wrought iron tests. Wrought is historically not entirely homogenous. This depended on th e quality of the ore and the reliability of the manufacturing processes During its short window of structural material dominance, wrought
7 iron manufacturing made huge strides advancing refinery technologies and processes. This subsequently led to its de mise as a popular structural material. History of Wrought Iron Manufacture of Wrought Iron Mankind has been using iron for over 5000 years. Items that were likely made of iron by Egyptians da te from 2500 to 3000 BC (Weeks 1968) Iron was often harder a nd more durable than bronze moving civilization out of the Bronze Age and into the Iron Age. This led to better and longer lasting tools and weapons. The evolution of iron manufactur ing is representative of the evolution of many technolog ies throughout t he history of civilization. S tarting as a crude technique made in a simple fire wrought iron manufacturing changed over centuries to large industrial scale mills and furnaces. The two parts of the process that have never changed are the iron ore and the heat. Wrought iron manufacture began with a fir e heated hole in the ground using a natural draft T he raw ore was added to the fire heated and then beaten into shape As the need for more heat became necessary to produce larger tools and larger quantit ies of iron bellows and other mechanically assisted drafts were used to increase the heat of the fire. Across Europe, Asia, and the Middle East furnaces were being developed to better control the production of iron that had now became a mainstay for tool s and weapons The next large milestone was the Catalan hearth furnace in the 13th century in Spain The Catalan furnace could produce up to three times more iron than previous furnaces (Aitchison 1960) From there, furnaces remained largely unchanged fo r hundreds of years making minor design improvements, bu t relying on the same process. The addition of shaft s, like in the Osmund furnace is an example of improvement in design. Everything changed in 1784 when Henry Cort patented a new process called th e puddling process for producing wrought iron. (Bowman 2004) This reverberatory furnace was a major improvement to the hearth furnace. It
8 separated the hearth containing the iron and the burning fuel connecting them by a bridge to transfer the hot air an d gas. This furnace was able to produce 20 times the amount of wrought iron produced using older met hods in the same amount of time (Bowman 2004) The dry puddling process was further improved to a wet puddling process changing the bottom of the furnace from sand and brick to iron silicate A brief description of the process is as follows: The cast or pig iron was used as the raw material loaded into the fire bridge. The hot gases passed over and fused the charge of the iron. The most of the metalloid i mpurities were removed by oxidation. After the refining operation, the puddle balls were transferred to the squeezer and rolled to desir ed shapes such as flat sections ( Chomsrimake 20 12 ) W rought iron production expanded from here through the American Rev olution and the Industrial Revolution in both the United States and Europe making wrought iron a very popular and widely used construction material Wrought iron aided in the birth of engineering and construction industries in the United States and many w rought iron structures still exist today. In 1855, the greatest ferrous metall urgy development was introduced, t he Pneumatic Bessemer Converter Steel production had begun and for the first time, the iron ore could be completely liquefied due to super hea ted pressure blasts Henry Bessemer had achieved This further oxidized and rid the iron of impurities. At first, steel was too brittle and too expensive to use, but like wrought iron had evolved, so did steel. The addition of carbon from other elements like manganese and iron, similar to the steel used today, made steel ductile, strong, and superior. As the manufacturing and construction industries slowly changed and accepted steel, wrought iron use in large scale construction was fading out by the en d of the 19 th century Applications of Structural Wrought Iron The fabricated metal truss bridge is one of the most important developments of American building technology (DeL ony 1993) As the rolling process improved throughout the 19 th century, the a vailability and diversity of structural shapes also improved. The railroad was a dominant transportation force and both rail and bridges were being constructed from wrought iron. Cast iron had failed on occasio n and steel was still brittle, unknown or n ot accepted by
9 engineers Wrought iron could also be used for both tension and compression members, where cast iron had primarily been only compression members. Peter Cooper was the first to roll structural shapes in the United States, at his T renton Iro n Works in New Jersey (Watters 2013) These shapes and section were riveted as their size was still relatively limited by the manufacturing processes of the time. Like Trenton Iron works, iron companies nationwide were standardizing their own rolled shap es. AISC compiled many of the shapes and section s half way through the 20 th century to aid the growing field of engineering design. I n the 19 th century, structural engineers were emerging and developing their new field As the iron companies grew, they started designing, patenting, manufacturing, and constructing wrought iron bridges for railroad and roadway. Figure 2.3 is an example a pamphlet advertising a wrought iron bridge for a roadway from the Canton, OH based Wrought Iron Bridge Company. Wrou for decades. Advanced engineering and assembly practices enabled American bridge companies to compete successfully in world markets with a pin connected, wrought iron bridg e product called the "American system" by foreign competitors. Progressive shop practices, standardized parts, and labor saving pinned, rather than riveted, connections that enabled quicker erection at remote sites ensured that the prices quoted by America n bridge manufacturers were the lowest and thei r completion dates the earliest (DeLony 1993) The invention of the elevator supplemented with the rise of steel eliminated the small presence wrought iron had in building construction as the United States tr ansitioned into the skyscraper eras of the early 20 th century. Steel, as discussed prior, replaced wrought iron in railroads and bridges as well, but thousands of wrought iron bridges existed worldwide Today, as few as 74 cast and wrought iron bridges f rom 1840 to 1880 are still in use in the United States (DeLony 1993) The surviving cast and wrought iron bridges in America are an outstanding group of engineering and manufacturing structures, each representing a rare example of American bridge design a nd manufacturing prowess. (DeLony 1993)
10 Brittle Failure In the United States, it is well known that many areas have very harsh winters. The 60 F. (SCEC 2006) This temperature is well below the expected temperature range for consistent ductile behavior for ferrous metals. Much empirical evidence had been accumulated by the 1920/1930s which showed that high strain rates applied at temperatures close to or somewhat below room temperature in t he presence of notches are more likely to result in brittle or sudden failure. (World Steel Association 2012) There are many noted historical brittle failures of both wrought iron and steel. A few of these can be found in Table 2.2. The lack of well doc umented brittle failures in the 19 th century did not imply the wrought iron of that era was necessarily resistant to this failure, but implied that investigation and research was necessary to determine its reaction. Figure 2.3: Front page of Pamphlet from Wrought Iron Bridge Co. Canton OH (Bowman 2004)
11 Table 2.2: History of Brittle Fracture ( Adapted from World Steel Association 2012) Year Structure Temperature at failure ( C) Steel t hickness (mm) Age of s tructure (years) Comments 1904 Water tank 0 15.9 7 Crystalline appearance of fracture 1925 Oil storage tank 20 25.4 Rapid fall in temperature before accident 1940 Trussed bridge 14 52 2 3 Cracks started at welds, u nloaded 1943 Liberty Ships 2 Some ships broke completely into two pieces 1951 Plate girder bridge 1 63 3 Bridge inspected two weeks before incident, practically no traffic at time of incident. 1952 Oil/gas storage tank 8 27 On test, crack sta rted at weld repair. 1954 Post office building 1 15 25 0 During construction, combination of poor technique and cracks in weld. A study of wrought iron from the 1843 SS Great Britain toughness at room temperature, with an absor bed energy values as low as 4 6 J (3 .0 4.4 ft lb) at room temperature, and a ductile brittle transition temperature of about 50 C. (Morgan 1992) It is also believed the wrought iron rivets used with the steel plates of the RMS Titanic may have failed upon the famous 1912 impact with an iceberg. This failure would have been at low temperature. As observed in both the table and e xamples above, temperature plays a large role in ductility. As structural materials have beco me better understood over time brittle failure has been considered and design has been focused on achieving ductile failure criteria. In researching this thesis very little low temperature testing has been found in the literature and very little data about wrought iron low temperature performance has been collected. This demonstrates the need for understanding brittle and ductile failure within wrought iron to determine a ductile brittle transition temperature for historic wrought iron and its welded repairs. Education through large scale failure is no longer and never was an acceptable way to understand the materials we use in modern times.
12 Wrought Iron Used i n Testing All of the historic wrought iron used for this thesis was from Minnesota Bridge #5721. It was donated by the Minnesota Department of Transportation ( MnDOT ) Originally, the bridge was constructed in the the town of Sauk Centre, MN to cross the Sauk River. The 162 foot long Parker truss bridge was made of wrought iron members and wood timber decking. Originally, t he bridge enabled horses, wagons, buggies, and pede strians to cross the Sauk River (Johnson 2012) In 1937, the populatio n and rise in automobile use had deemed the bridge insufficient for demand. At that point, the bridge was disassemble d and reassembled in Koochiching County in northern Minnesota over the Little Fork River where it was known as the Silverdale Bridge. 70 years of carrying logging trucks and other traffic, it was once again ruled insufficient. The condition of the bridge had deteriorated to point that large scale repair and rehabilitation was required. MnDOT moved the bridge into storage in 2009. Eight o f the original wrought iron eye bar truss members were replaced with new s teel members (Watters 2013) Six of the eight of the removed eye bars were donated to the University of Colorado Denver in 2012 and were used as the wrought iron bar stock for testi ng and analysis in this thesis. Wrought iron from members one (M1) three (M3) and five (M5) were used in testing They were originally members U2W L3W, U2E L3E and U2E L3E respectively as shown in Figure 2. 4 The bridge also underwent deck replaceme nt amongst other repairs. Upon completion in 2011, MnDOT reinstalled the bridge in Stillwater, MN as a part of the Gateway called the Gateway Trail Iron Bridge over Manning Avenue. It once again allows the transport of ped estrian, cycling, and equestrian traffic. Minnesota Bridge #5721 in its current and previous location can be seen in Fig. 2.4 and Fig. 2.5. Figure 2.6 : Member lay out of Bridge #572 North South
13 Repair of Structural Wrought Iron Awareness and appreciation of historic bridges has increased since the 1980s. More and more transportation planners and bridge engineers recognize the value of historic bridges and work with local communities and preservation groups to save them (DeLony 1993) The desire to preserve and continue to use these bridges leads to the need for repair and rehabilitation. Many state DOTs have developed historic bridge programs, like the one responsible for Minnesota Bridge #5721, and across the nation ( including Colorado ) For historic truss bridges, common problems usually consist of u n symmetric connections, severely strained and damaged pins, eye Figure 2. 5 : Silverdale Bridge #5721 in Koochiching County ( MnDOT 2012 Used with permission. ) Figure 2. 6 : Gateway Trail Iron Bridge over Manning Ave (CR 15) in Washington County ( MnDOT 2012 Used with permission. )
14 bar cracking and failure, elongated and slack members, traffic damaged and bent members, and various stages of corrosion resulting in loss of cross section (Bowman 2004) To achieve the stand ard of inspection and repair of modern bridges for the problems listed above modern repair and construction techniques must be used. Most modern structural metals, particularly ferrous metals such as steel, are installed, constructed, and repaired often u sing welding at some point. These proven modern repair methods and data supporting them need to be available to historic structural wrought iron. Research and testing on structural wrought iron that will be discussed in Chapter III and IV exists, but re search has yet to exhaustively cover and provide data necessary for sound prescriptive technique s and procedure s
15 CHAPTER III SHIELDED METAL ARC WELDING General Information Even though a multitude of welding techniques exist today, SMAW has been chose n as one of the preferred methods for use on historic structural wrought iron. Also known as stick welding, i t is a popular type of welding that is commonly used for in situ repair in modern construction. SMAW is often used to weld carbon steel, low and high alloy steel, stainless steel, cast iron, and ductile iron (Chomsrimake 2012) All of the welding performed for this research and thesis was SMAW. Other welding methods are not discussed. Based on the prior research of SMAW by Preeda Chomsrimake and Joel Watters at UCD and research on wrought iron repair by Mark Bowman at Purdue University, SMAW and many other specifications within this specific method have been identified as successful techniques to be used with historic wrought iron. SMAW is a fu sion welding process that melts a flux coated metal electrode using the heat of an electric ar c with the joining base metal. A diagram of SMAW can be found in Figure 3.1. Both the base metal and electrode melt. The flux provides a shielding gas and molt en slag during Figu re 3.1 : SMAW Diagram (Adapted from Bridigum 2008) Flux coating Electrode Shielding gases Molten weld pool Protective solidified slag Solidified weld Molten metal and slag Depth of penetration Base metal Weld direction
16 the process protecting the weld from impurities or contamination. This slag is different than the siliceous slag found in the composition of wrought iron. The metal part of the electrode provides the filler material that mixes with and fus es the base metal parts together. There are many types of electrodes that vary in metal type, metal strength, and flux coating. The si ze of the electrode also varies, and is dictated by the weld type and welding position. The arc is provided by generat ing power and trying to create a circuit with the electrode and base metal. The power source, a generator, provides a constant current (CC) from either an alternating current (AC) or a direct current (DC) power supply. DC power is most commonly used for SMAW due to the consistent, steady current. The welding circuit uses voltage in volts, which is governed by the arc length between the electrode and the base metal, and is influenced Figure 3.2 : Arc welding c ircuits ( Adapted from Bridigum 2008) Electrode holder Electrode Lead clamp Negative lead Ground Electrode holder Electrode Lead clamp Positive lead Ground Negative terminal Negative lead Negative terminal Positive lead Positive Terminal Positive Terminal Direct Current Electrode Positive (DCEP) Direct Current Electrode Negative (DCEN)
17 by metal type and electrode size. Current, measured in amperes called a mps, is also used to control the power and heat of the welding circuit. The welder manually controls the arc distance, or arc gap, while the current is generally set for the specific weld. The power supply, usually a generator, consists of a transformer and if DC, a rectifier to convert AC to DC. This is common as most generators are run off of high voltage AC. The transformer reduces the voltage and increases the current to pro vide the necessary current for welding. There are many types of welding g enerators in existence, and are not discussed in this thesis. Insulated clamps, called leads are connected to the generator. One lead holds the electrode and the other lead is clamped to the bench holding the metal to be welded or to the metal directly. For DC, the flow of current can be changed to flow either direction within the generator. If the current is flowing through the electrode into the base metal through the other lead clamp, this is called direct current electrode positive (DCEP). The oppo site direction of current flow is called direct current electrode negative (DCEN). shown above in Figure 3.2. All of the variables and choices within SMAW are determined by the weld specifications provided by code or design Weld Qualifications The metal composition, metal thickness, joint type, penetration required, weld strength required, weld size, and position of the weld all play a part in selecting polarity and electrode. Once the polarity and electrode has been chosen the current can be selected and the weld performed. The AWS has codes and standards for most welding techniques and methods, but little for wrought iron or SMAW with wrought iron. This means that there is no official WPS for welding wrought iron. A w elding procedure specification sets guidelines for the shop and field welding practice of the fabricator for each anticipated com bination of essential variables (Chomsrimake 2012) ired by AWS code, all production welding shall be performed in conformance with the provisions of an approved welding procedure specification (WPS), which is based upon successful test
18 results as recorded in a Procedure Qualification Record (PQR) unless qu alified in conformance with AWS1.3.1 (AASHTO, 2010). A part of the goal of this research is to perform tests required and determine if a future PQR could be obtained to develop a WPS for historic structural wrought iron. The CVN test to measure relativ e fracture toughness is one of the tests required in this process of determining if a WPS can be approved. Future research which will be further discussed in Chapter V I, can address other testing to continue to work towards a WPS for welding historic wrou ght iron. Procedure for Wrought Iron Basis for Research Specifications For this research, the welding specifications were kept at a constant. Based on the tensile testing and bend testing, repairing wrought iron bridge members with single V groove wel ding in proved satisfactory (Chomsrimake 2012) The Chomsrimake research also preheated the wrought iron to 300 F prior to welding. Again, based on tensile testing and bend testing, using a double bevel full penetration groove weld with a groove angle of 60 with a preheat temperature of 300 F was recommended (Watters 2013) In both of the mentioned research proj ects the face bend tests failed. Due to the smaller heat affected zone (HAZ) observed using the double bevel full penetration groove weld; this joint was selected to perform toughness tests for SMAW on historic wrought iron. The welds performed for this research were very similar to those performed for the research of Joel Watters at UCD Welding Performed for Research The same wrought iron stock used in the research by both Preeda Chomsrimake and Joel Watters was again used for this testing. The spark tests performed on the wrought iron samples gave the researchers confidence that the metal being tested was indeed historic wrought iron, even without the opportunity to per form detailed chemical analysis (Watters 2013) More
19 recommendations were made by Bill Campbell the welding instructor at Western Colorado Community College (WCCC) Some of his recommendations were used in the following specification. The specifications used for the welding are : 1. Base metal: historic structural wrought iron 2. Welding type: Shielded metal arc welding (SMAW) 3. Joint type: double bevel butt joint 4. Penetration: full penetration 5. Root b ack gouging: Yes 6. Start/Run off tabs: Yes 7. Electrode: E7018 8. Amperage: Determined by the skilled welder See Figure 3.3 for the following parameters : 9. 10. 11. See Figure 3.3 for a detailed drawing of the proposed weld. See Figure 3.4 and 3.5 for the weld coupon and welds located within the wrought iron bridge member respectively. WCCC provided this research with weld coupons b ased on what their time permitted. The testing specimens, discussed in Chapter IV, were made from these Figure 3.3 : Double bevel full penetration groove weld (Watters 2013)
20 coupons The symbols in Figure 3.4 are standard weld callouts for the prior specifications listed. The coupons were approximately three inches long, Minor variations, flaws, and defects in the wrought iron from original manufacture were present, but not measured as they would be removed during specimen milling. The wrought iron was covered in lead based paint that was removed prior to sending to WCCC. The wrought iron was measured and marked for cutting and welding, as can be seen in Figure 3.5. The pieces were further grinded a negligible amount to clean and prepare the wrought iron for welding. Figure 3.4: Drawing of weld coupon Figure 3.5: Weld coupons being measured and marked at WCCC
21 In Figure 3. 6 performed in this thesis. The quality assurance documentation for each weld is discussed in the next section and can individually be found in Appendix D Not all of the welded coupons produced were used in testing. Upon preparation of the testing specimen s discussed in Chapter s IV and V welding defects were found in some of the coupons, and were noted during testing.
22 Figure 3.6: Drawing of planned weld coupons from wrought iron bridge member
23 CHAPTER I V CHARPY V NOTCH IMPACT TESTING History and Backgroun d For some materials and temperatures the results of impact tests on notched specimens, when correlated with service experience, have been found to predict the likelihood of brittle fracture accurately (ASTM 2002) The Charpy v notch test, sometimes cal led the Charpy impact test, is a standardized test that determines the amount of energy absorbed by a material during fracture. Historically, the impact pendulum test method and associated apparatus were suggested (in nearly their current forms) by S. B. Russell in 1898 (Russell, 1898) and G. Charpy in 190 1 (Tth 2002 ) A.G .A. Charpy can be seen in Figure 4.1 with the paper in which he presented his version of the impact pendulum test Charpy had modified the pendulum, standardized the specimen sizes, an d produced thorough literature on using the test. This led to the test becoming Figure 4.1: Augustine Georges Albert Charpy and the cover of the original paper ( Adapted from Tth 2002) Tth
24 his namesake due his technical contributions and developing standardization of material testing in the early 20 th century. Impact testing evolved as engineering evolved in th e 20 th century, beginning as testing procedures started to become standardized. Science and engineering by adjusting to failure pushed by the brittle failures discussed in Chapter III furthered material sciences and demonstrat e the need to understand how materials work in all service conditions. In much of the testing that was being and had been developed. Today, sub size specimens, instrumented impact testing, and extreme control of tests have allowed impact test to become a part of many material, design, and construction standards. of work is a tool to study the temperature dependent ductile brittle transition. The test determines a materials toughness, or resistance to fracture. Even though there is both a quantitative and qualitative results from CVN tests, these results are only compara tive. The quantitative result of the impact tests give us foot pounds (or inch pounds depending on the precision of the machine) requ ired to fracture the material. The qualitative result is determined by analyzing the fract ure plane, or lack thereof. An example of a brittle and ductile fracture plane from this research can be found in Figure 4.2 The machine used in testing shown in Figure 4.3, consists of a pendulum of known length and m ass dropped from a known height that impacts a notched specimen. The Tinius Olsen Model 55 specification sheet can be found in Appendix E At the point of impact, the striker has a known amount of kinetic energy. The impact energy is calculated based on the height to which the striker would have risen, if no test specimen was in place, and this compared to the height to w hich the striker actually rises (AZoM.com 2005) Calibration was not performed specifically for this testing due to lack of resources. Error to account for windage and calibration will be di scussed in Chapter s V and VI. As mentioned
25 Figure 4.2: Welded wrought iron brittle (above) and ductile (below) fracture planes.
26 earlier, impact testers have not changed drastically since their original use in the beginning of the 20th century. The original documentation of the machine can be found in Appendix E. The notch creates a stress concentration zone to try to control the fracture location so the results are comparative. As the specimen tears along the fracture plane, most of the impact energy is absorbed during plastic deformation of the material. Wrought iron, and other fe rrous materials that have a body centered cubic crystal structure, lose ductility as the temperature decreases. As mentioned before, one of the common goals of impact testing is to determine the ductile brittle transition temperature (DBTT), also known as the nil ductility temperature (NDT). These temperatures are derived as the energy needed to fracture noticeably reduces. Usually, this is not an exact temperature, but a range of temperatures k nown as the transition region. Figure 4.3: Tinius Olsen Model 55 Charpy Impact Tester
27 Qualitatively or upon inspect ion, if the material has a flat, coarse fracture plane then the fracture fracture plane has jagged and stretched edges described as shear lips then the fracture was ductile. Figure 4.2 shows instances of both of types of fr acture. Often, especially when approaching the DBTT, evidence of both types of fracture will be present. The amount of each type can be calculated as a percentage of the fracture plane area. Quantitatively, as the data is empirically collected, it is re latively simple to plot temperature versus recorded work. Typical toughness measurements will be discussed with the test results in Chapter s V and VI. Failure mechanisms leading to the fracture during testing can also be analyzed and will be discussed i n Chapter s V and VI. Preparation of Specimens As a reference, this research used ASTM E23 02a, Standard Test Methods for Notched Bar Impact Testing of Metallic Materials. This standard served as a basis for testing procedure and data collection. Not a ll of the specifications required by ASTM were adhered to due to limited tools and resources, but the testing was performed as close to the standard as could be reasonably performed by this researcher. The initial specimen s were designed based on the Figure 4.4 : Charpy (Simple Be am) Impact Test Specimens, Type A. ( Adapted from ASTM 2002)
28 deta ils found in Figure 4.4. Machined in the University of Colorado Denver machine shop, all of the weld coupons received from WCCC were milled and cut into 10mm by 10mm by 50mm specimens with a 45 2mm notch at the midway point on the face corresponding wit h the top of bottom of the theoretically symmetrical double bevel groove weld. The specimens were measured by a digital caliper prior to testing as a reference. All of these recorded measurements can be found in Appendix A. Specimens were noted if their tolerances were not within ASTM E23 specification, but were still used unless there was an extreme defect or dimensional error. In Figure 4.5, a specimen is shown where you can see the notch in relation to the weld (and some voids in the weld, a defect to be discussed later). Throughout the welding, machining, and testing processes, the specimens were tracked and labeled based on their original member in bridge #5721 and from whi ch weld coupon they came from. Figure 4.5 : Machi ned specimen. Note: Weld defects
29 To be discussed in Chapter V, after initia l testing the specimens were cut to accommodate problems in initial testing. This led to the majority of the pieces by cut lengthwise, again by the UCD machine shop. A picture of the new specimen size can be found in Figure 4.6. The way the specimens wer e cut, led to minor material loss due to the width of the band saw used. The new dimensions were record ed prior to testing as mentioned above, and can be found in Appendix A, too Testing Procedure CVN tests are fairly simple at room temperature. Lif t the pendulum until it is locked in the upright position (as shown in Figure 4.3 above). Place the specimen in the testing machine approximately centered as shown in Figure 4.7 and 4. 8 Set the dial to 120 ft lbs. Then, release the lever which in turn r eleases the pendulum. The machine moves the dial to the energy used to Figure 4.6 : Machined specimen after width adjustment.
30 fracture the specimen. The work performed on the specimen is recorded as well as observations about the fracture plane. When this testing required temperatures less than room tempera ture a cooling bath was required. Bath mixtures of ethanol and ethylene glycol in dry ice produce sustainable constant temperatures over the range from 12 to 78 C. (Lee 200) The chemicals and equipment used for the cooling bath are shown in Figure. 4. 9 For surface temperature determination, an infrared thermometer with a range of 55 to 1022 F was used. For cooling bath temperature determination, a probe thermometer with the range of 58 to 300 F was used. The lowest temperature was chosen to be within the range of the probe thermometer. The range of testing temperatures corresponds with the extreme weather records consistent within the United States, as mentioned earlier. The ratio of chemicals in the cooling bath can be found in Appendix A. AS TM E23 specifies that the specimens must be submerged by the cooling bath by at least an inch on all sides. A piece of coat hanger was bent to make a stand for the bottom of the bowls used for the bath as shown in Figure 4. 10 For a majority of the testi ng the bath consisted of dry ice placed in ethanol. The ethanol used was grain alcohol with a purity of 95% ethanol. Dry ice was used in no specific quantity, but added periodically to the bath to get the temperature lower or to sustain a certain tempera ture. For warmer temperatures, ethylene glycol (laboratory grade coolant) was used. Discussed in the detailed testing report in C hapter V, the exact contents of the cooling bath were documented for each set of specimen. The specification also requires th e specimen soak at a desired temperature for five minutes prior to testing and there is a five second window to move the specimen from the bath to the Charpy testing machine to try and prevent temperature change during transit and while sitting in the test ing machine. The specimens were put into the bath at a temperature colder than the the bath. The temperature of the bath was taken and recorded immediately prior to moving the specimen from the bath to the machine. The machine had been marked t o facilitate quick
31 center ing of t he specimen shown in Figure 4.11 The tongs used for transfer were also submerged in the cooling bath to avoid heating up the specime ns in transfer. Three specimens were tested for each temperature listed in Chapter V. Both welded and non welded specimens were t ested for comparative purposes. After specimens were tested, they were cleaned and re labeled as the ethanol dissolved and f aded the identifying marks. Quantitative and qualitative results were recorded from the energy recorded on the machine and by taking pictures of the fractured specimens. The pictures from testing can be found in Appendix C. The exact procedural list is found in Chapter V along with more detail and analysis from testing. Figure 4.7 : Charpy Simple Beam Impact Test. ( Adapted from ASTM 2002)
32 Figure 4.8 : A specimen in the testing machi ne. Figure 4.9 : Cooling bath equipment and chemicals.
33 Figure 4.10 : Stand used to keep specimens off the bottom of the bath. Figure 4.11 : Specimen position markings in the testing machine.
34 CHAPTER V RESULTS AND ANALYSIS Testing Report As described in the previous chapter, Charpy V N otch impact tests were performed on welded and non welded solid historic structur al wrought iron. The process of testing was as follows: 1. Set the dial of the testing machine to 120 ft lbs. 2. Raise the pendulum into the locked position. 3. Measure and record the dimensions of the specimen with digital caliper. 4. Put the specimen in the cooling bath at a temperature cooler than the desired test temperature since the room temperature specimen warms the bath. 5. Hold the temperature of the bath within 2 F of the desired testing temperature for at least five minutes. 6. Record the temperature of the bath prior to specimen removal. 7. Remove the specimen from the bath and place centered in the testing machine. 8. Release the pendulum. 9. Record the energy reading from the testing machine. 10. Take pictures of the fractured specimen. This process was repeated for every recorded specimen. The only deviation from this list was for room temperature specimens for which steps four through six were not necessary. General Testing Notes The tests for welded wrought iron were performed at eight different temperatures. The design temperatures were r oom temperature, which was generally around 75 F, and every 20 degrees from +65 to 55 F. Each specimen s exact bath temperature was recorded. The tests for non welded wrought iron were performed at only three different temperatures due to the limited
35 amount of specimens av ailable at the time of tes ting. Room temperature, +10, and 55 F were the temperatures used for the non welded specimens. This range was chosen to be consistent with the welded specimens so that th e results could be compared. Prior to testing, the pendulum was released with no s pecimen in the machine to check the machines calibration and accuracy. The machine registered at 4.5 ft lbs. The recorded values in testing were not adjusted for this reading. Upon brief discussion a mechanical engineering professor Dr. Ron Rorrer durin g the initial testing in the lab (February 28, 2014) it was determined that the accuracy of the machine was still sufficient, but that there was a general friction and windage loss of this amount. This thesis will refer to all such losses as a windage lo ss. After research on windage losses, t he general losses are attributed to the imperfections and unaccounted forces in the testing machine including, but not limited to; air resistance, friction, slipping, machine vibration and movement, etc. The machine which weighs approximately 1115 pounds, was not bolted to the floor. Possible, but imperceivable movement of the base could have contributed to some of this loss. In the first round of testing, it was observed that at room temperature, the majority o f t he welded specimens were either stopping the pendulum and not fracturing or barely fracturing and not registering an energy reading on the dial. Upon further testing, successful tests were conducted, but only at very low temperatures or when the welds had severe visual defects Even though these tests were not successful, their limited results can be found in Table 5.1 in the test results section As the specimen temperature was raised, the disqualifying occurrences started to happen once again. It w as then determined that the toughness of wrought iron, and welded wrought iron was too high for the capacity of the machine being used. I t was determined to reduce the cross sectional area of the specimen, to bring the energy required for fracture within the range of the impact test machine. The only dimension of the specimens to be changed was the width, w. The notation used for the dimensions of the specimens can be found in Figure 5.1. No data analysis was performed on the initial round of testing.
36 Once the specimens were cut to the new dimensions, the exact same testing procedure listed above was used. Again, a ll of the recorded dimensions for each specimen can be found in the tables in Appendix A As expected, the specimens fractured and energy was recorded by the machine for the new dimensions every time. The results were compared to known historic structural wrought iron tests performed by other research ers as well as this research to try and confirm whether the welded wrought iron behaved sim ilar to the non welded wrought iron as hypothesized. The results of the final testing can be found in Table 5.2 in the test results section Limitations The major limitations of this research were equipment based. The testing machine itself and the cooling bath used for temperature control could have been controlled better with more expensive and more technologically advanced equipment that was available. Machining the specimens, controlling the temperature, and performing the test itself can all be performed within many modern material labs and testing facilities. The fabrication technology needed to machine the specimens within the ASTM dimensional tolerances exist. Electronically controlled cooling baths that keep constant temperatures also exis t. Equipment specifically developed to perform the CVN tests, such as notched tongs and machines designed for quick and precise placement of the specimen exist as well. Knowing the limitations of this research, this researcher understands that this thesi s serves as a basis for further study and continued investigation into the toughness of Figure 5.1 : Specimen dimensional notation.
37 welded wrought iron. Recommendations for further testing and research can be found in Chapter VI. CVN Test Results The following tables contain all of the recorded i nformation from the Charpy V N otch impact testing. Table 5.1, has several pieces of missing data. Once it was determined that the first round of testing was a trial to familiarize the researcher with the machine and techniques to be used, some of the dim ensions were not recorded and as mentioned before, many specimens failed to fracture or record an energy on the machine. Never the less, Table 5.1 summarizes the initial tests. These missing data are represented by dashes in the table. The specimen with asterisks had severe weld defects and will be discussed in the data analysis section. The temperatures with asterisks were room temperature and did not use a cooling bath. No data analyses were performed on the initial testing results. The temperature g oals are found in Table 5.2. The average actual recorded temperatures were within two degrees of the temperature goal. The recorded energies are also shown in this table. Table 5.3 shows all of the recorded data from the second and final testing. All d ata was included so that a complete study and data analysis could be performed. The same format and notation was used from the table for initial testing for the table for final testing. The welded specimens having several weld defects were tested at room temperature. Defective welds led to less energy being required to fracture the specimen and an average energy that is lower than expected. This average energy was less than the energy required to fracture good specimens at ten degrees colder. The table shows that as the temperature was increased, the amount of energy required to fracture the specimen also increased. This is consistent with other ferrous metals that are less ductile as lower temperatures and will be discussed further in Chapter VI.
38 Ta ble 5.1: Initial CVN Testing Results February 28, 2014 Dimensions Energy (ft lbs) Bath Temperature ( F) Specimen L D W x1 y1 x2 y2 Initial Trials M1 1 55.11 10.19 10.1 26.94 8.1 28.17 2.09 80.1* M1 5.1 40 M1 5.2 55.01 9.98 10.16 27.48 8.13 27.53 1.85 87.5 76 M1 9.1 55.1 10.04 10.13 27.52 8.15 27.58 1.89 76 M1 9.2 76 Welded M1 8.1 55.06 9.84 10.18 27.04 8.06 28.02 1.78 15.5 65 M1 8.2 55.15 9.89 10.04 27.13 8.06 28.02 1.83 65 M1 8.3 55.18 10.03 1 0.13 26.92 8.02 28.26 2.01 81 63 M1 12.1 55.14 9.82 10.15 27.02 8.04 28.12 1.78 104.5 34.3 M1 12.2 55.01 10.06 10.02 27.19 8.05 27.82 2.01 114 32.4 M1 12.3 55.05 9.82 10.14 27.12 8.04 27.93 1.78 31.7 M1 13.1 55.02 10.01 10.05 8.14 1.87 7.8 M1 13.2 55.04 9.98 10.14 8.09 1.89 6.6 M1 13.3 55.07 9.9 10.15 7.97 1.93 70 4.7 Severe Weld Defects M1 11.1* 55.06 10.1 5.2 27.02 8.15 28.04 1.95 20 76.6* M1 11.2* 55.12 9.94 3.59 27.14 8.02 27.98 1.92 8 76.6* M1 11.3* 55.09 9.96 4.77 27 8.05 28.09 1.91 39 76.6* M1 11.4* 55.17 10.05 3.82 27.09 8.06 28.08 1.99 10 76.6* Non welded M3.1 55.02 10.03 9.93 27.24 8.12 27.78 1.91 6.5 65 M3.2 55.04 10.1 10.05 27.13 8.12 27.91 1.98 60.2 M3.3 55.15 10.08 9.99 27.62 8.12 27.53 1.96 8 56.3 M3.4 55.06 10.02 10.01 27.36 8.12 27.7 1.9 8 55.9 = Visible weld defects = Room Temperature Table 5.2: Average Results and Temperature Goals April 2, 2014 Energy (ft lbs) Temperature ( F) Temperature Goal ( F) Welded 19.3 56.7 55 23 .5 36.1 35 32.0 15.2 15 42.0 4.6 5 51.6 24.6 25 63.8 44.6 45 67.3 64.7 65 56.8 76.5 RT Non welded 7.5 54.8 55 25.8 9.1 10 55.3 74.3 RT RT = room temperature
39 Table 5. 3 : Final CVN Testing Results April 2, 2014 Dimensions Energy (ft lbs) Bath Temperature ( F) Specimen L D W x1 y1 x2 y2 Welded M1 4.4* 55.14 9.97 4.39 26.99 8.23 28.15 1.74 20.5 58.2 M1 4.5* 55.14 9.90 4.26 26.98 8.25 28.16 1.65 21.5 57.1 M1 4.6* 55.10 10.17 4.09 27.14 8.34 27.96 1.83 16.0 54.7 M1 6.1 54.95 9.87 3.83 27.03 8.05 2 7.92 1.82 18.5 38.1 M1 6.2 54.94 9.85 3.80 27.25 8.09 27.69 1.76 23.0 36.2 M1 6.3 54.92 9.98 4.01 27.26 8.30 27.66 1.68 29.0 34.1 M1 6.4 55.02 9.89 4.32 27.25 8.24 27.77 1.65 35.6 16.7 M1 6.5 55.15 10.04 4.19 27.25 8.15 27.90 1.89 40.5 14.9 M1 6.6 55.16 9.95 4.65 27.47 8.18 27.69 1.77 20.0 14.0 M1 7.1* 54.75 9.00 4.15 27.10 7.68 27.65 1.32 40.0 3.9 M1 7.2 54.80 9.67 3.91 27.11 7.62 27.69 2.05 50.5 4.2 M1 7.3* 54.88 9.81 4.03 27.10 7.96 27.78 1.85 35.5 5.6 M1 7.4 54.73 9.69 4.04 27.08 7.76 27.65 1.93 60.5 23.9 M1 7.5 54.82 9.17 3.50 26.77 8.04 28.05 1.13 38.5 24.0 M1 7.6 54.79 9.07 3.84 26.77 7.79 28.02 1.28 55.9 25.9 M1 14.1* 55.02 10.04 4.05 27.23 8.12 27.79 1.92 66.5 44.0 M1 14.2 55.07 9.84 4.08 27.29 7.94 27.78 1.90 58.0 44 .8 M1 14.3 55.04 9.92 4.16 27.11 8.12 27.93 1.80 67.0 45.0 M1 14.4 54.94 9.90 4.14 27.01 8.11 27.93 1.79 65.5 63.2 M1 14.5 55.10 9.94 4.13 27.41 8.08 27.69 1.86 75.5 64.4 M1 14.6 55.08 10.02 4.00 27.41 8.10 27.67 1.92 61.0 66.6 M1 4.1* 55.07 9.93 4.00 27.12 8.51 27.95 1.42 51.0 76.7* M1 4.2* 55.13 9.93 4.41 26.91 8.40 28.22 1.53 53.5 76.5* M1 4.3 55.11 10.12 4.25 27.15 8.35 27.96 1.77 66.0 76.4* Non welded M3.1 54.96 9.88 4.18 26.89 8.26 28.07 1.62 58.0 74.4* M3.2 54.93 9.85 3.97 26.90 8.27 28.03 1.58 52.5 74.1* M3.6 55.01 9.95 3.94 27.55 8.13 27.46 1.82 18.5 9.5 M3.7 54.97 9.96 4.01 27.11 8.30 27.86 1.66 26.0 7.4 M3.8 55.03 9.93 4.13 27.45 8.20 27.58 1.73 33.0 10.5 M3.3 55.17 10.15 4.40 27.27 8.35 27.90 1.80 7.5 56.3 M3.4 55.19 1 0.13 4.05 27.26 8.40 27.93 1.73 8.0 54.8 M3.5 55.15 10.15 4.28 27.00 8.54 28.15 1.61 7.0 53.2 = Visible weld defects = Room Temperature More tables and plots are presented in Appendix B. All of the photos from the final round of testing are pre sented in Appendix C.
40 Data Analysis In order to compare the welded and non welded specimens and their toughness es derived from the impact testing, the average of each set of specimens from each specific temperature was calculated Here, results from thos e specimens with defective welds have been omitted In Table 5.4, the difference in the averages between the welded and non welded specimen are compared. Data points to match temperatures was also linearly interpolated and extrapolated to compare hypothe tical energies at the same temperatures. Even though the Charpy curve is non linear, piecewise linear approximations can be made. Because the filler material of the welds came from E7018 electrodes, the minimum tensile strength of the filler material i s 70 ksi. The wrought iron used for testing was found to have an average ultimate tensile strength of 50 ksi. (Watters 2013) It can be expected that the non welded wrought iron would be weaker than the welded wrought iron in toughness testing as well. The difference in energy and the percent less tough between the welded and non welded wrought iron is also shown in Table 5.4. Error between the Charpy curve and the piecewise linear approximation was not calculated. Table 5.4: Welded vs. Non welded Aver age Energies Welded Extra/Interpolation Welded Values Non Welded Between Welded and Non Welded Energy (ft lbs) Temperature ( F) Energy (ft lbs) Temperature ( F) Energy (ft lbs) Temperature ( F) (ft lbs) Reduction in Toughness (%) 69.1 75 55.3 74.3 13.8 20.1 67.33 64.7 63.83 44.6 51.63 24.6 44.6 10 25.8 9.1 18.8 42.1 42.00 4.6 32.03 15.2 23.50 36.1 19.33 56.7 19.3 56.7 7.5 54.8 11.8 61.2 14.8 41.1 lbs) Average % Less
41 The average difference in energy between welded and non welded wrought iron was almost 15 ft lbs. The differences were not drastically different and as expected the welded specimens demonstrated more toughness than th e non welded specimens. Table 5.4 also shows the percent of toughness lost between the welded and non welded specimens. Again, at lower temperature s the energy required for fracture also lowers, and a comparison of the change in energy per change in time can be found in Table 5.5. This change is almost identical for both the welded and the non welded specimen demonstrating that even though the welded specimens are tougher overall, toughness reduces at a similar rate to the non welded specimens as the te mperature is lowered. Table 5.5: Change in Energy over Change in Temperature Energy (ft lbs) Energy (ft lbs) Temperature ( F) Temperature ( F) Temperature (ft lbs/ F) Welded 67.33 64.7 3.50 63.83 44.6 20.1 12.20 51 .63 24.6 20.0 9.63 42.00 4.6 20.0 9.97 32.03 15.2 19.8 8.53 23.50 36.1 20.9 4.17 19.33 56.7 20.5 8.00 20.2 0.39 54 Non Welded 55.25 74.3 29.42 25.83 9.1 65.1 18.33 7.50 54.8 63.9 23.88 64.51 0.37 01 These tests demonstrate that the welded specimens behaved in an expected manner when compared to both other wrought iron and other ferrous metals, like steel A typical Charpy curve for steel can be found in Appendix B. T he welded specimens were tougher than the non welded wrought iron, but lost ductility in a similar manner. When compared to values from the Bowman paper on historic structural wrought iron (Bowman 2004) the e nergies were consistent ly lower than the data from this research. The tables and a plot from the Bowman paper can be found in
42 Appendix B. Different sources of historic wrought iron imply potentially different properties. anisotropic material The exact locations of the slag stringers are unknown and this can lead to variations in values during toughness testing. Charpy curves were made from this research s data to observe the transition from brittle to ductile as the temperature increased These plots can be found in Appendix B. There are plots both with the room temperature welded specimen included and excluded as well as plots of the average energy for each temperature goal An approximate duct ile brittle transition temperature (DBTT) for welded wrought iron has been graphically determined, too. The curves are included are approximate third order polynomials and are fo r observational purposes only. Qualitatively, photos are located in Appendix C. Each specimen is shown along with a comment based on judgment of whether the majority of the fracture plane was ductile or brittle. Instead of calculating a percent brittle or ductile of the fracture plane, five designations were used; brittle, mostl y brittle, brittle/ductile, mostly ductile, and ductile. Table 5.6 lists the ductile and brittle fracture plane observations as well as whether or not the piece completely broke in two. The energy reduction for not breaking found in the ASTM standard was not applied. An approximate DBTT can be observed around 25 F from fracture plane observation and a large increase in recorded energy. The majority of the specimens had evidence of both brittle and ductile failure mechanisms. The coldest tested specimens were mostly if not all brittle. Often the specimen fractu red on the edge of the weld, especially if there were any defects present. Many specimens, though they showed brittle failure mechanisms, would split longitudinally due to the location of a slag stringer and its negligible strength. As the temperature wa s raised, even though still cold, the or e ductile. Clearly, wrought iron is a very ductile material. The addition of welds did not reduce the ductility and even increased the observed
43 ductility at the testing temperatu res that were used for both the we lded and non welded spe cimens. Recommendations and future research can be found in Chapter VI. Table 5.6: Qualitative CVN Test Results Specimen Energy (ft lbs) Bath Temperature ( F) Majority of Fracture Plane Did it completely fracture ? Welded M1 4.4* 20.5 58.2 Mostly brittle Yes M1 4.5* 21.5 57.1 Mostly brittle Yes M1 4.6* 16 54.7 Brittle/Ductile Yes M1 6.1 18.5 38.1 Brittle/Ductile Yes M1 6.2 23 36.2 Brittle/Ductil e Yes M1 6.3 29 34.1 Brittle/Ductile Yes M1 6.4 35.6 16.7 Brittle/Ductile Yes M1 6.5 40.5 14.9 Mostly Ductile Yes M1 6.6 20 14 Brittle/Ductile Yes M1 7.1* 40 3.9 Mostly Ductile Yes M1 7.2 50.5 4.2 Ductile No M1 7.3* 35.5 5.6 Mostly Ductil e No M1 7.4 60.5 23.9 Mostly Ductile No M1 7.5 38.5 24 Brittle/Ductile No M1 7.6 55.9 25.9 Mostly Ductile No M1 14.1* 66.5 44 Mostly Ductile No M1 14.2 58 44.8 Mostly Ductile No M1 14.3 67 45 Mostly Ductile No M1 14.4 65.5 63.2 Ductile No M 1 14.5 75.5 64.4 Ductile No M1 14.6 61 66.6 Brittle/Ductile Yes M1 4.1* 51 76.7* Ductile Yes M1 4.2* 53.5 76.5* Ductile Yes M1 4.3 66 76.4* Ductile Yes Non welded M3.3 7.5 56.3 Brittle Yes M3.4 8 54.8 Brittle Yes M3.5 7 53.2 Brittle Yes M 3.6 18.5 9.5 Brittle Yes M3.7 26 7.4 Mostly Brittle No M3.8 33 10.5 Mostly Brittle No M3.1 58 74.4* Ductile No M3.2 52.5 74.1* Ductile No = Visible weld defects = Room Temperature
44 CHAPTER VI SUMMARY AND RECOMMENDATIONS Summary of Testing and Results The historic structural wrought iron from Minnesota Bridge #5721 has continued to provide for research, form data, and create a knowledge base for understanding the way this historic material behaves. The C harpy V N otch impact tests performe d provid e more insight into the behavior of this ferrous metal at different temperatures. The performance of welded wrought iron can be considered tougher than that of non welded wrought iron. This statement is supported by the higher energy required to fracture welded wrought iron at all temperatures. The loss of ductility as the temperature of the metal is lowered is standard for ferrous metals and there were no grossly unexplained or unexpected results These qualitative and quantitative results were compared to other published non welded wrought iron data which in turn served as a comparison for the welded wrought iron data. The toughness of this historic material is important as long standing wrought iron bridges throughout America need assessment and repairs and can be found in locations subject to low temperatures. Recommendations The data and understanding of the testing performed are important, but the end goal is to standardize and approve a welding technique for historic wrought iron. Bas ed on the results of the impact tests, the welds remained intact at most temperatures. It is important to note the fracture often occurred at the weld base metal interface. This testing lends credence to support the use of t he double bevel full penetrati on groove weld using the E7018 electrodes and the other welding specifications listed in this thesis a s an appropriate method for the repair of historic structural wrought iron. As seen in this research, slight defects in the weld greatly reduce the tough ness. The approximate DBTT is well below average ambient temperature for most
45 structures, but l ow temperature impacts, such as a vehicle striking a truss member on a bridge during winter, could still lead to brittle failure. Continued and Future Research The specific nature of this thesis leaves a lot of area for expansion into the future and continued research. T esting a larger amount of specimens will give more data and ensure that the true nature of welded wrought iron at various temperatures is obse rved. Outside of this specific testing, as mentioned by other theses from UCD, investigating other weld types, specifications, and techniques should be performed so that when a WPS is finally standardized, the supporting data is exhaustive. This research er recommends that bridge use, probabilistic event occurrence, and more wrought iron material behaviors all need to be studied before a proper repair or rehabilitation is made on any historic wrought iron structure to ensure the safety of all and the prote ction of valuable historic structures. Maximizing the lifespan of historic wrought iron structures will need this continued research to ensure that proper repair and rehabilitation are published and available worldwide. Applying and using modern techniqu es and technology will only help in assessing and working with historic structures making continued research important for engineers, contractors, DOTs, and preservationists alike.
46 REFERENCES Aitchison, L. (1960) A History of Metals 2 vols. London, M acdonald & Evans Ltd. American Association of State Highway Transportation Offices (AASHTO) Edition, Washington DC ASTM E23 (2002). Standard Test Methods for Notched Bar Impact Testing of Metallic Materia ls American Society of Testing Materials, West Conshohocken PA. Aston, J. & Story, E. (1939) Applications (2nd Edition), A.M. Byers & CO, Pittsburgh, PA Bowm an, M. & Piskorowski, A. (2004) n and Repair of Wrought Iron and Steel Brandt, D. & Warner J. (2005) Metallurgy Fundamentals: Ferrous and Non ferrous (5 th Edition), The Goodheart Wilcox Company, Inc., Ti nley Park, IL Bridigum, T. (2008) How To Weld Motorbooks Workshop, MBI Publishing Company, Minneapolis, MN Chomsrimake, P. (2012) r, CO DeLony, E. (1993) and Wrought Wrought Iron and Steel Bridges The Journal of the Society for Industrial Archeology, Vol. 19, No. 2, pp. 17 47 Johnson, R. & Olson, S. (2012) Lead to 3rd Structure Magazine Vol. 19, No. 10, pp. 29 31 Lee, D.W. & Jensen, C.M. (2000) Journal of Chemical Education Vol. 77 No. 5 Morgan, J. & Hooper R. (19 92) Metals and Materials, The Journal of the Institute of Metals, Vol. 8, pp. 655 Rorrer, Ron (2014) Personal communication. Associate Professor of Mechanical Engineering, University of Colorado Denver, Feb. 2 8. State Climate Extremes Committee (SCEC) (2006) Records National Climatic Data Center, National Oceanic and Atmospheric Adm inistration. Web. 10 March, 2014 Tth, L., Rossmanith, H. P., Siewart, T.A. (2002) From Charpy to Present Impact Testing ESIS Publication 30, 2002, pp. 3 Tiemann, H (1919) Iron and Steel, A Pocket Encyclopedia McGraw Hill, New York, NY.
47 ds for the Repair CO Weeks, M., Leichester, H. (1968). Discovery of the Elements Journal of Chemical Education. pp. 29 World Steel Association (2012) History of Brittle Failures, steeluniversity.org. Web. 10 March, 2014
48 APPENDIX A SPECIMEN DRAWINGS AND MEASUREMENT TABLES Figure A.2 : Specimen dimensional notation. Figure A.1 : Charpy (Simple Be am) Impact Test Specimens, Type A. ( Ad apted from ASTM 2002)
49 Table A.1: Initial CVN Test Dimensions Dimensions Cross sectional area at mid specimen Specimen L D W x1 y1 x2 y2 Welded M1 1 55.11 10.19 10.1 26.94 8.1 28.17 2.09 81.81 M1 5.1 M1 5.2 55.01 9.98 10.16 27.48 8.13 27.53 1.85 82.60 M1 9.1 55.1 10.04 10.13 27.52 8.15 27.58 1.89 82.56 M1 9.2 M1 8.1 55.06 9.84 10 .18 27.04 8.06 28.02 1.78 82.05 M1 8.2 55.15 9.89 10.04 27.13 8.06 28.02 1.83 80.92 M1 8.3 55.18 10.03 10.13 26.92 8.02 28.26 2.01 81.24 M1 12.1 55.14 9.82 10.15 27.02 8.04 28.12 1.78 81.61 M1 12.2 55.01 10.06 10.02 27.19 8.05 27.82 2.01 80.66 M1 12.3 55.05 9.82 10.14 27.12 8.04 27.93 1.78 81.53 M1 13.1 55.02 10.01 10.05 8.14 1.87 81.81 M1 13.2 55.04 9.98 10.14 8.09 1.89 82.03 M1 13.3 55.07 9.9 10.15 7.97 1.93 80.90 M1 11.1 55.06 10.1 5.2 27.02 8.15 28.04 1.95 42.38 M1 11.2 5 5.12 9.94 3.59 27.14 8.02 27.98 1.92 28.79 M1 11.3 55.09 9.96 4.77 27 8.05 28.09 1.91 38.40 M1 11.4 55.17 10.05 3.82 27.09 8.06 28.08 1.99 30.79 Non Welded M3.1 55.02 10.03 9.93 27.24 8.12 27.78 1.91 80.63 M3.2 55.04 10.1 10.05 27.13 8.12 27.91 1.98 81.61 M3.3 55.15 10.08 9.99 27.62 8.12 27.53 1.96 81.12 M3.4 55.06 10.02 10.01 27.36 8.12 27.7 1.9 81.28
50 Table A.2: Final CVN Test Dimensions Dimensions Cross sectional area at mid specimen Specimen L D W x1 y1 x2 y2 Welded M1 4.4 55.14 9.97 4. 39 26.99 8.23 28.15 1.74 36.13 M1 4.5 55.14 9.9 4.26 26.98 8.25 28.16 1.65 35.15 M1 4.6 55.1 10.17 4.09 27.14 8.34 27.96 1.83 34.11 M1 6.1 54.95 9.87 3.83 27.03 8.05 27.92 1.82 30.83 M1 6.2 54.94 9.85 3.8 27.25 8.09 27.69 1.76 30.74 M1 6.3 54.92 9.98 4.01 27.26 8.3 27.66 1.68 33.28 M1 6.4 55.02 9.89 4.32 27.25 8.24 27.77 1.65 35.60 M1 6.5 55.15 10.04 4.19 27.25 8.15 27.9 1.89 34.15 M1 6.6 55.16 9.95 4.65 27.47 8.18 27.69 1.77 38.04 M1 7.1 54.75 9 4.15 27.1 7.68 27.65 1.32 31.87 M1 7.2 54 .8 9.67 3.91 27.11 7.62 27.69 2.05 29.79 M1 7.3 54.88 9.81 4.03 27.1 7.96 27.78 1.85 32.08 M1 7.4 54.73 9.69 4.04 27.08 7.76 27.65 1.93 31.35 M1 7.5 54.82 9.17 3.5 26.77 8.04 28.05 1.13 28.14 M1 7.6 54.79 9.07 3.84 26.77 7.79 28.02 1.28 29.91 M1 14.1 55.02 10.04 4.05 27.23 8.12 27.79 1.92 32.89 M1 14.2 55.07 9.84 4.08 27.29 7.94 27.78 1.9 32.40 M1 14.3 55.04 9.92 4.16 27.11 8.12 27.93 1.8 33.78 M1 14.4 54.94 9.9 4.14 27.01 8.11 27.93 1.79 33.58 M1 14.5 55.1 9.94 4.13 27.41 8.08 27.69 1.86 33.37 M1 14.6 55.08 10.02 4 27.41 8.1 27.67 1.92 32.40 M1 4.1 55.07 9.93 4 27.12 8.51 27.95 1.42 34.04 M1 4.2 55.13 9.93 4.41 26.91 8.4 28.22 1.53 37.04 M1 4.3 55.11 10.12 4.25 27.15 8.35 27.96 1.77 35.49 Non Welded M3.1 54.96 9.88 4.18 26.89 8.26 28.07 1.62 34.53 M3.2 54.93 9.85 3.97 26.9 8.27 28.03 1.58 32.83 M3.6 55.01 9.95 3.94 27.55 8.13 27.46 1.82 32.03 M3.7 54.97 9.96 4.01 27.11 8.3 27.86 1.66 33.28 M3.8 55.03 9.93 4.13 27.45 8.2 27.58 1.73 33.87 M3.3 55.17 10.15 4.4 27.27 8.35 27. 9 1.8 36.74 M3.4 55.19 10.13 4.05 27.26 8.4 27.93 1.73 34.02 M3.5 55.15 10.15 4.28 27 8.54 28.15 1.61 36.55
51 Table A.3: Cooling Bath Quantities Bath composition (with dry ice) Specimen Bath Temperature ( F) Ethanol (mL) Ethylene glycol (mL) M1 4.4 58.2 1000 0 M1 4.5 57.1 1000 0 M1 4.6 54.7 1000 0 M1 6.1 38.1 1000 0 M1 6.2 36.2 1000 0 M1 6.3 34.1 1000 0 M1 6.4 16.7 1000 0 M1 6.5 14.9 1000 0 M1 6.6 14.0 1000 0 M1 7.1 3.9 1000 0 M1 7.2 4. 2 1000 0 M1 7.3 5.6 1000 0 M1 7.4 23.9 1000 0 M1 7.5 24.0 1000 0 M1 7.6 25.9 1000 0 M1 14.1 44.0 750 250 M1 14.2 44.8 750 250 M1 14.3 45.0 750 250 M1 14.4 63.2 500 500 M1 14.5 64.4 500 500 M1 14.6 66.6 500 500 M1 4.1 76.7* M1 4.2 76.5* M1 4.3 76.4* M3.3 56.3 1000 0 M3.4 54.8 1000 0 M3.5 53.2 1000 0 M3.6 9.5 1000 0 M3.7 7.4 1000 0 M3.8 10.5 1000 0 M3.1 74.4* M3.2 74.1* Room Temperature =
52 APPENDIX B CVN TEST PLOTS AND TABLES Figure B.1 : Welded Wrought Iron CVN Test Results 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 -80.0 -60.0 -40.0 -20.0 0.0 20.0 40.0 60.0 80.0 100.0 Energy (ft lbs) Test results Average values
53 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 -80.0 -60.0 -40.0 -20.0 0.0 20.0 40.0 60.0 80.0 Energy (ft lbs) Test results Average values Figure B.2 : Welded Wrought Iron Adjusted CVN Test Results (without weld defect results)
54 Figure B.3 : Non welded Wrought Iron CVN Test R esults 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 -80.0 -60.0 -40.0 -20.0 0.0 20.0 40.0 60.0 80.0 100.0 Energy (ft lbs) Test results Average values
55 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 -80.0 -60.0 -40.0 -20.0 0.0 20.0 40.0 60.0 80.0 100.0 Energy (ft lbs) Non-welded wrought iron test results Non-welded wrought iron average values Welded wrought iron test results Welded wrought iron average values Figure B.4 : CVN Test Results
56 Figure B.5 : Adjusted CVN Test Results (without weld defect results) 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 -80.0 -60.0 -40.0 -20.0 0.0 20.0 40.0 60.0 80.0 100.0 Energy (ft lbs) Non-welded wrought iron test results Non-welded wrought iron average values Welded wrought iron test results Welded wrought iron average values
57 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 -80.0 -60.0 -40.0 -20.0 0.0 20.0 40.0 60.0 80.0 100.0 Energy (ft lbs) Non-welded wrought iron average values Welded wrought iron average values Approximate Welded Wrought Iron DBTT Figure B.6 : Adjusted CVN Average Test Results
58 Figure B.7 : Charpy Impact Testing Results (Bowman 2004)
59 Table B.1 : Charpy Impact Test Resul ts (Bowman 2004)
60 Figure B.8 : Adjusted CVN Comparative Average Test Results 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 -80.0 -60.0 -40.0 -20.0 0.0 20.0 40.0 60.0 80.0 100.0 Energy (ft lbs) Non-welded wrought iron average values Welded wrought iron average values Approximate Wrought Iron DBTT Wrought Iron average results (Bowman 2002)
61 40 22 4 14 32 50 68 86 104 122 140 158 176 Temperature F (Converted from Celsius) 221 184 148 111 74 37 0 Energy Absorbed ft lb (Converted from Joules ) Figure B. 9 : Typical steel Charpy curve ( Adapted from World Steel Association 2012)
62 APPE NDIX C CVN TESTING PHOTOGRAPHS Figure C.1 : Specimen M1 4.4, tested at 58.2 F
63 Figure C.2 : Specimen M1 4.5, tested at 57.1 F
64 Figure C.3 : Specimen M1 4.6, tested at 54.7 F
65 Figure C.4 : Specimen M1 6 .1, tested at 38.1 F
66 Figure C.5 : Specimen M1 6.2, tested at 36.2 F
67 Figure C.6 : Specimen M1 6.3, tested at 34.1 F
68 Figure C.7 : Specimen M1 6.4, tested at 16.7 F
69 Figure C.8 : Specimen M1 6.5, tested at 14.9 F
70 Figure C.9 : Specimen M1 6.6, te sted at 14.0 F
71 Figure C.10 : Specimen M1 7.1, tested at 3.9 F
72 Figure C.11 : Specimen M1 7.2, tested at 4.2 F
73 Figure C.12 : Specimen M1 7.3, tested at 5.6 F
74 Figure C.13 : Specimen M1 7.4, tested at 23.9 F
75 Figure C.14 : Specimen M1 7.5, tested at 24.0 F
76 Figure C.15 : Specimen M1 7.6, tested at 25.9 F
77 Figure C.16 : Specimen M1 14.1, tested at 44.0 F
78 Figure C.17 : Specimen M1 14.2, tested at 44.8 F
79 Figure C.18 : Specimen M1 14.3, tested at 45.0 F
80 Figure C.19 : Specimen M1 14.4, tested at 63 .2 F
81 Figure C.20 : Specimen M1 14.5, tested at 64.4 F
82 Figure C.21 : Specimen M1 14.6, tested at 66.6 F
83 Figure C.22 : Specimen M1 4.1, tested at 76.7 F
84 Figure C.23 : Specimen M1 4.2, tested at 76.5 F
85 Figure C.24 : Specimen M1 4.3, tested at 76.4 F
86 Figure C.25 : Specimen M3.3, tested at 56.3 F
87 Figure C.26 : Specimen M3.4, tested at 54.8 F
88 Figure C.27 : Specimen M3.5, tested at 53.2 F
89 Figure C.28 : Specimen M3.6, tested at 9.5 F
90 Figure C.29 : Specimen M3.7, tested at 7.4 F
91 Figure C.30 : Specimen M3.8, tested at 10.5 F
92 Figure C.31 : Specimen M3.1, tested at 74.4 F
93 Figure C.32 : Specimen M3.2, tested at 74.1 F
94 APPENDIX D TESTING MACHINE Figure D.1 : Testing machine documentation, page 1
95 Figure D.2 : Testing machine documentation, page 2
96 Figure D.3 : Testi ng machine documentation, page 3
97 Figure D.4 : Testing machine documentation, page 4
98 Figure D.5 : Testing machine documentation, page 5
99 APPENDIX E WELD QUALITY ASSURANCE SHEETS (All welding performed at Western Colorado Commun ity College, Fall 2013) Figure E.1 : M1 1 QA Sheet
100 Figure E.3 : M1 5 QA Sheet Figure E.2 : M1 4 QA Sheet
101 Figure E.4 : M1 6 QA Sheet Figure E.5 : M1 7 QA Sheet
102 Figure E.6 : M1 8 QA Sheet Figure E.7 : M1 9 QA Sheet
103 Figure E.8 : M1 11 QA Sheet Figure E.9 : M1 12 QA Sheet
104 Figure E.10 : M1 13 QA Sheet Figure E.11 : M1 14 QA Sheet