LAUSR

The deep-rolling, mechanical surface treatment was modified by applying heat during operation on the martensitic stainless steel AISI 420. Fatigue performance of the high-temperature deep-rolled condition was investigated and compared with the non-surface-treated and room-temperature deep-rolled conditions. Thermal and mechanical relaxation behaviors of residual stresses and work-hardening states were investigated. Annealing processes were carried out at a temperature range of 300-600 °C, with soaking times between 0.1 and 10 4  min for thermal relaxation. Fatigue tests were carried out at given stress amplitudes of 517-600 MPa, with the different number of cycles for the mechanical relaxation. The residual stresses and work-hardening states were determined using x-ray diffraction with the sin 2 Ψ method. It was found that the thermal relaxation can be described with the Zener–Wert–Avrami function. The relaxation mechanism was changed from the volume diffusion of the room-temperature deep-rolled condition to the dislocation-cored diffusion of the high-temperature deep-rolled condition. The mechanical relaxation of compressive residual stresses was higher than that of the work-hardening states. The residual stresses of the high-temperature deep-rolled condition are more stable than those of the room-temperature deep-rolled condition under cyclic loading.