The inducement of residual stress through deep rolling of AISI 1060 steel and its subsequent relaxation under cyclic loading

Abstract

The inducement of compressive residual stress by means of deep rolling (also known as ball or roller burnishing) has been widely investigated over the last decades; however, the influence of cyclic loading on stress relaxation of rolled components has not received the same attention. Therefore, the principal aim of this work is to study the behaviour of macro- and microresidual stresses (the latter assessed in terms of the full width at half maximum, FWHM) on the surface of AISI 1060 steel specimens under rotating bending tests. For this purpose, samples with three distinct heat treatments (subcritical annealing, full annealing and hardening by quenching and tempering) were deep rolled at various combinations of rolling pressure and number of passes. The results indicate that the tensile residual stress obtained after turning shifted to compressive stress after deep rolling. The FWHM decreased after deep rolling at the lowest pressure, thus suggesting that deep rolling promoted a better distribution of the dislocations induced by previous turning; however, the further elevation of rolling pressure and number of passes caused the elevation of the FWHM. The macro- and microresidual stress values were not drastically altered after rotating bending testing with an applied stress corresponding to 50 % of the yield strength. Nevertheless, residual stress relaxation was observed with an applied stress of 80 % of the yield strength, though the FWHM did not provide evidence of microresidual stress relaxation. Finally, the analysis of the fractured cross-sections of hardened specimens indicated that the location of the crack initiation site deepens with the elevation of rolling pressure.