A study on the numerical analysis of thermomechanical behaviour in a stud-to-plate laser braze joint

A mechanical analysis of stud-to-plate laser brazing was performed using th e finite element method, and the transient displacement and stress fields i n brazing workpieces were calculated. The materials used were small-diamete r studs of AISI type 304 stainless steel, thin plates of Al 5052 aluminium and 88Al-12Si braze alloy for the filler metal. The mechanical analysis too k account of the thermal aspects of brazing and the transient temperature f ields were calculated using a brazing heat transfer model. An incremental p lasticity model was employed for thermal elastoplastic analysis, which cons idered the temperature-dependent mechanical properties and the isotropic ha rdening effect of the materials. The numerical result showed that high resi dual tensile stresses remained in the middle of the braze gap, approaching the yield point of type 304 stainless steel. The permanent deformation of w orkpieces after the brazing was completed was minimal and confined to the a rea adjacent to the joint. Stress peaks were found to exist along the joini ng interfaces, which were due to mismatches in thermal and mechanical prope rties among the materials involved.