Effect of precipitate–precipitate interaction on residual stress in welded structure

The process of assembly by welding led to the creation of micro-structural heterogeneities zones. Generally these zones can be discontinuities macroscopic geometrical (macro-geometry of the weld nugget) or/and geometrical or metallurgical defects. At the origins of stress concentration, these regions are favorable sites where fatigue cracks can initiate and propagate. Our work concerns the role of the existence of the precipitate during the process of welding on the level of the microscopic internal stress thermal origin. The distribution of this stress in the steel matrix around these defects was the subject of a numerical analysis by the finite element method. The originality of this study lies in the angle of attack in the volume fraction of the precipitate and the effect of precipitate–precipitate interaction on the distribution and the level of this stress. The precipitate in the steel matrix resulting from a process of welding generates thermal stress whose level reaches its maximum value with the interface matrix–precipitate. Far from this interface the matrix is completely released of this stress. This stress can constitute a risk of damage to the welding joint.