Evaluation and Repair of Wrought Iron and - Purdue e-Pubs ...
Evaluation and Repair of Wrought Iron and - Purdue e-Pubs ... Evaluation and Repair of Wrought Iron and - Purdue e-Pubs ...
8imperfections, the performance of the material will vary considerably. The properties ofthe material depend on the iron ore it was manufactured from and the individual that wasmanufacturing it. Since it is difficult to find consistency in both of these dependencies, itis also extremely difficult to find consistency in the material properties.2.1.2 Manufacturing Process of Historic Wrought IronIn 1784 Henry Cort patented a new process called the puddling process forproducing wrought iron. In this process, a reverberatory type furnace was utilized inheating the iron ore. This furnace consisted of a “firebox”, where the fuel was burned,and was separated from the hearth, which contained the iron ore, by a bridge (Dennis,1963).After separating the iron ore, from the heat source, the iron ore was placed in alarge hearth that was typically 6 feet by 4 feet in dimensions, which in Henry Cort’soriginal furnace was lined with fire-brick and sand. Unfortunately the iron ore wouldoften oxidize with the sand creating extra iron-silicate slag and therefore reducing theamount of iron produced by 30% (Aston, 1949).The amount of impurities in the wrought iron was reduced in 1830 when JosephHall modified Cort’s process, known as “dry puddling”, by lining the hearth with olderhearth material such as iron silicate which contained iron oxide. This change increasedthe yield of wrought iron from iron ore, or pig iron, to 90% (Dennis, 1963). This newprocess became known as “wet puddling”.Figure 2.2 shows a section of the puddling furnace as described above. Thepuddling furnace capacity ranged from 300 pounds to 1500 pounds of wrought iron perheat (Johnson, 1928). A single heat typically took about one and a half hours tocomplete. After heating, the wrought iron was shaped into a ball, commonly called a
9bloom or sponge ball. Slag was dispersed through out the iron in small pockets at thisstage and the structure of the hot wrought iron can then be compared to a commonsponge.The ball was then transported, while remaining at high temperatures, to a rotarysqueezer. A photograph of a sponge ball being transported can be seen in Figure 2.3. Inthe squeezer, the iron was “squeezed” and “shingled” mechanically to remove most of theslag existing in the wrought iron. After being squeezed, the puddle ball was less than halfthe original size and then rolled into shape. The rolling process elongated the remainingexisting slag deposits in one direction created a semi-fibrous structural state.The rolling process began when the wrought iron sponge ball was transferred tothe rolling mill where it would be rolled into needed shapes. First, the ball was rolledinto small rectangular bars, known as “muck bars”. These muck bars were rolled to be athickness of 2 to 4 inches and then cut into strips. The strips were then piled up andwired together, reheated to a welding temperature and then rolled again (Mills, 1915).The finished product, called a “merchant bar”, was then either sold or further rolled intodifferent shapes.The wrought iron manufactured from the puddling process has large deposits ofimpurities. The majority of these impurities are commonly known as “slag”. The termslag refers to a molten substance that is found in the furnace other than the iron ore beingprocessed. This substance is mechanically intertwined in the material during processing(Tiemann, 1919). In historic wrought iron, slag consists mainly of iron silicate alongwith other miscellaneous oxides. The percent of slag found in the iron ranges from oneto three percent by weight (Aston, 1949).The wrought iron manufactured today is made from a process similar to that ofsteel. Iron is superheated to a liquid form, where most of the impurities are separated.Then a pre-produced molten slag is added to create the definitive slag deposits found in
- Page 1 and 2: Purdue UniversityPurdue e-PubsJTRP
- Page 3: 1. Report No. 2. Government Accessi
- Page 6 and 7: epairing a bent wrought iron tensio
- Page 8 and 9: vPageCHAPTER 3TEST PROCEDURES FOR M
- Page 10 and 11: ixLIST OF FIGURESFigurePageFigure 1
- Page 12 and 13: xiFigurePageFigure 3.30 Top View of
- Page 14 and 15: xiiiFigurePageFigure 5.12 Typical T
- Page 16 and 17: xvAppendix FigurePageFigure D.7 Ini
- Page 18 and 19: viiiAppendix TablePageTable A.5 Det
- Page 20 and 21: iiiThe authors would also like to t
- Page 22 and 23: 2but also what material properties
- Page 24 and 25: 4microstructure of the metal. The c
- Page 26 and 27: 62. LITERATURE SEARCHBefore experim
- Page 30 and 31: 10wrought iron. Adding the slag aft
- Page 32 and 33: 12method for manufacturing wrought
- Page 34 and 35: 14patents for their process and tra
- Page 36 and 37: 16This method of testing of structu
- Page 38 and 39: 18plot of this percent elongation d
- Page 40 and 41: 20significant variation in the perc
- Page 42 and 43: 22The practice of restoring histori
- Page 44 and 45: 24Elleby, Wallace W. Sanders, F. Wa
- Page 46 and 47: 26From all the surveys that were di
- Page 48 and 49: 28Table 2.1 Average Ultimate Streng
- Page 50 and 51: 30Figure 2.3 Wrought Iron “Sponge
- Page 52 and 53: 32Histogram of Kirkaldy Wrought Iro
- Page 54 and 55: 34Percent Occurance in Range - %45.
- Page 56 and 57: 3660Combined Wrought Iron BarsTensi
- Page 58 and 59: 38The Bell Ford Bridge consisted of
- Page 60 and 61: 40Two. These samples were taken fro
- Page 62 and 63: 42specimens were of constant cross
- Page 64 and 65: 44Along with rectangular tensile co
- Page 66 and 67: 46After the initial test loading wa
- Page 68 and 69: 483.6 Fatigue TestingTo develop a b
- Page 70 and 71: 50The final specimen category consi
- Page 72 and 73: 52This analysis was completed using
- Page 74 and 75: 54After the initial test was comple
- Page 76 and 77: 56completed, but before the surface
9bloom or sponge ball. Slag was dispersed through out the iron in small pockets at thisstage <strong>and</strong> the structure <strong>of</strong> the hot wrought iron can then be compared to a commonsponge.The ball was then transported, while remaining at high temperatures, to a rotarysqueezer. A photograph <strong>of</strong> a sponge ball being transported can be seen in Figure 2.3. Inthe squeezer, the iron was “squeezed” <strong>and</strong> “shingled” mechanically to remove most <strong>of</strong> theslag existing in the wrought iron. After being squeezed, the puddle ball was less than halfthe original size <strong>and</strong> then rolled into shape. The rolling process elongated the remainingexisting slag deposits in one direction created a semi-fibrous structural state.The rolling process began when the wrought iron sponge ball was transferred tothe rolling mill where it would be rolled into needed shapes. First, the ball was rolledinto small rectangular bars, known as “muck bars”. These muck bars were rolled to be athickness <strong>of</strong> 2 to 4 inches <strong>and</strong> then cut into strips. The strips were then piled up <strong>and</strong>wired together, reheated to a welding temperature <strong>and</strong> then rolled again (Mills, 1915).The finished product, called a “merchant bar”, was then either sold or further rolled intodifferent shapes.The wrought iron manufactured from the puddling process has large deposits <strong>of</strong>impurities. The majority <strong>of</strong> these impurities are commonly known as “slag”. The termslag refers to a molten substance that is found in the furnace other than the iron ore beingprocessed. This substance is mechanically intertwined in the material during processing(Tiemann, 1919). In historic wrought iron, slag consists mainly <strong>of</strong> iron silicate alongwith other miscellaneous oxides. The percent <strong>of</strong> slag found in the iron ranges from oneto three percent by weight (Aston, 1949).The wrought iron manufactured today is made from a process similar to that <strong>of</strong>steel. <strong>Iron</strong> is superheated to a liquid form, where most <strong>of</strong> the impurities are separated.Then a pre-produced molten slag is added to create the definitive slag deposits found in
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