Relaxation strahlbedingter Eigenspannungen unter kombiniert thermisch-mechanischer Beanspruchung in Laserstrahl-Schweißverbindungen einer AlSiMgCu-Knetlegierung

Abstract

Welding of precipitation hardened aluminum alloys causes microstructures with inferior mechanical properties compared to the base material. Surface treatments like shot peening are appropriate methods to increase the fatigue strength of these welded materials. In order to evaluate the stability of induced residual stresses in thermo-mechanical service conditions, the residual stress relaxation, the creep and relaxation behavior of alloy 6056 was examined under mechanical loads and temperatures from 100°C to 150°C. Residual stresses relaxed to a higher grade in the welding and heat affected zone compared to the base material. High stress exponents of creep tests indicated threshold stress behavior what could be confirmed by results of relaxation tests. Calculation of Orowan s stresses for β -precipitations gave values in the same range of threshold stresses. Compared to load stress relaxation residual stresses relaxed to a higher amount.