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

81the rest of the molten iron. This leads to separation of the iron sulfide and the creation ofinclusions, which decrease the overall strength of the wrought iron.4.3 Hardness Test ResultsHardness is a measurement of the resistance to permanent indentation of amaterial. The resulting values from hardness testing depend directly upon the test thatwas performed and, therefore, is not a fundamental property and can be arbitrary. Evenso, hardness is still determined for many materials because of its relationship with otherfundamental properties, such as tensile stress.In the material testing that was completed for this research, the Rockwell Bhardness test was performed on wrought iron samples from the Bell Ford Bridge. Theaverage of all the resulting hardness values was 70 with a standard deviation of 6.5. Tocorrelate this value to the tensile strength of the metal, Table 3, of ASTM A370 (1997a)which contained the approximate hardness conversions for nonaustenitic steels wasutilized. The average hardness corresponded to a tensile strength of 61 ksi if the materialwas a nonaustenitic steel. This value is considerably higher than the tensile results foundfrom other mechanical material testing on wrought iron. Therefore, the hardnessconversion charts for steel are not an accurate method to relate the hardness of wroughtiron to its tensile strength. The hardness of the wrought iron may be higher thanstructural steel for a certain tensile strength.A comparison of the tensile strength data from experimental testing to thehardness data was completed for wrought iron. In this comparison it was determined thatif the hardness for the wrought iron is linearly related to the tensile strength, the tensilestrength may be roughly estimated by multiplying the hardness value (from Rockwell BHardness Test) by 655. Due to the lack of more hardness data from other sources, this