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

874.4.4 Results of the Heat Straightened SpecimensFour of the rectangular tensile testing specimens were heat straightened beforethey were tested. The procedure that was used to heat straighten these tensile couponspecimens was outlined in Chapter 3. These specimens were machined from the BellFord Bridge material and, therefore, were compared to the tensile specimens taken fromthe same bridge that were not heat straightened.When comparing the tensile strength and yield strength of the heat straightenedspecimens to the regular (not heat straightened) specimens, little difference in the valueswas observed. Figure 4.14, for example, illustrates the tensile strength values.Moreover, if the percent elongations of the heat straightened specimens is compared tothe regular specimens, there is again very little effect on the specimen ductility, as Figure4.15 demonstrates.4.4.5 Results of the Mechanically Straightened SpecimenOne of the tensile coupon specimens from the Bell Ford bridge was mechanicallystraightened. The procedure utilized in straightening this bar without heat was presentedin Chapter 3. The properties of the mechanically straighten bar were compared to theother non treated bars from the Bell Ford bridge. The tensile strength of the mechanicallystraightened bar was only 37,500 psi and the percent elongation was only 3.1%. Figure4.16 is a plot of the percent elongations from all the tensile coupons with the result fromthe mechanically straightened bar highlighted. As the plot indicates, the percentelongation for this specimen is considerably lower than any other specimen results.The lack of ductility and tensile strength in this specimen is directly related to theeffects induced from mechanically straightening the bar. When straightening the bar, thecold metal is forced past the yield stress until permanent deformations and residual