EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The Gas metal arc welding (GMAW) creates strong microstructure gradients generating residual stress fields that influence the mechanical response and service life of welded structures. Under mechanical loadings, the welding residual stresses can be relaxed or redistributed. This work attempts to study the relaxation of welding residual stress generated by GMAW. Three types of lap joints specimens have been tested to determine each fatigue strength for a full tensile uniaxial load. Subsequently, experimental investigations based on interrupted high cycle fatigue tests have been conducted. Residual stresses were analyzed before, during and after cyclic loads by means of X-ray diffraction. The welding residual stress evolution kinetics for high cycle fatigue loading have been identified. Furthermore, metallurgical analysis such as EBSD analysis were carried out on tested specimens to clearly identify the underlying mechanisms of welding residual stress relaxation. In fine, this work aims to propose a modelling to consider stress relaxation in numerical fatigue simulations for the assessment of automotive suspension steel parts.