In water surrounded areas there are many failures of stainless steels caused by stress corrosion cracking. If the surface of these materials is changed by peening processes, compressive residual stresses will be induced and stress corrosion cracking can not occur. For this reason stainless steel of type 316 Ti (1.4571) was shot peened and also high pressure water peened to induce compressive residual stresses in surface layers. During normal service conditions the strain hardened surface layers are exposed to elevated temperatures. The influence of time and different temperatures on the stability of residual stresses in surface layers were investigated. The relaxation of the residual stresses at the surface and in near surface areas was measured by X-ray diffraction. With the presented experimental results the effect of peening processes can be evaluated with respect to typical thermal loading effects.