Evaluation and Repair of Wrought Iron and - Purdue e-Pubs ...

39surfaces of these pieces were then ground smooth to remove the outer corrosive surfaces.Once the corrosion was removed, the pieces were then polished.This was done using a range of metallic grit paper of varying roughness. Initiallya very coarse paper was used to polish the specimens. Then finer grains of papers wereused to polish the specimens until finally a diamond powder and polishing wheel wasused to make the surfaces as smooth as possible. After polishing, a 2% Nitol solutionwas applied to the surface of the specimens to etch and make the microstructure visible.This same specimen preparation procedure was used to prepare a piece of carbon steelfrom the testing laboratory. The steel and wrought iron specimens were then comparedso that the differences in the microstructures of the two metals could be observed.To view the microstructure of the wrought iron, a microscope with a light sourcewas used to magnify the microstructure of the metal. A digital camera was attached tothis microscope and was used to photograph the magnified microstructure. To accuratelydetermine the magnification of the pictures, a magnifying ruler was placed onphotographs at various magnifications. The magnification of each photograph was thenfound by measuring the distance between the ruler marks on the photographs andcomparing that distance to the known distance between the marks of the ruler.The data acquired from the micrographs consisted of photographs taken of thewrought iron and steel. These photographs were magnified to approximately 100 timesand accurately showed the microstructure of both wrought iron and steel. An example ofthe photographs acquired can be seen in Figure 3.5.3.3 Chemical AnalysisThe specimens for the chemical analysis of wrought iron were taken frommembers of the Bell Ford Bridge. Two separate samples were cut from Eyebars One and