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

774. PRESENTATION OF TEST RESULTSIn addition to the mechanical and material testing completed, an in depthinvestigation of the results from this testing was also conducted. From these results, themechanical properties of historic wrought iron were evaluated and compared withhistorical data. An improved understanding of these mechanical properties will assistbridge engineers when they need to conduct a condition assessment of structuresconsisting of historic wrought iron. This is especially true for wrought iron truss bridgesconsisting of wrought iron eyebars, since mechanical testing was completed on a numberof eyebar coupons and connection eyes.4.1 MicrostructureTo determine the microstructure of historic wrought iron, an investigation of themicrographs that were taken during testing was completed. This investigationdetermined that the microstructure consisted of ferrite particles intermixed with manylarge inclusions that are typically elongated in one direction. Figure 4.1 is a photographof a typical micrograph taken during testing.The lighter areas in Figure 4.1 consist of mostly ferrite particles with some sparsedeposits of pearlite particles. These ferrite particles were larger and coarser than ferriteparticles commonly found in steel. Patches of pearlite were also found amongst theferrite particles in the microstructure of wrought iron. Pearlite is commonly found instructural steel and is the product that is formed from the infusion of carbon with iron.Pearlite is not as prevalent in wrought iron as in steel and is typically so sparse that any