Investigation of residual stress and mechanical properties of equal channel angular rolled St 12 strips

Equal channel angular rolling process is defined as a severe plastic deformation method that imposes very large plastic strain on a material in order to enhance its mechanical properties and grain structure refinement. In this study, residual stress profiles through the thickness of St 12 strips that were subjected to different passes of equal channel angular rolling were investigated by slitting method. Also, the effects of different routes of equal channel angular rolling (A and C) were studied on the mechanical properties and residual stress. Furthermore, the effect of post annealing on the mechanical properties and residual stress of 4-pass equal channel angular rolled strip was examined. The results showed significant increase in the yield strength, ultimate tensile strength, and micro hardness of the samples in both routes. But the elongation decreased. Considerable magnitude of residual stress was created through the thickness of equal channel angular rolled samples such that the maximum tensile residual stress of some samples raised to about half of the corresponding yield strength. The maximum magnitude of residual stress in route C was smaller than that in route A.