PNNL

Abstract

Many applications in the aerospace and automotive industry demand the use of lightweight materials such as magnesium alloys to reduce weight and increase fuel efficiency. Still, in some critical sections, the use of much stronger materials such as steel is inevitable. The large difference in melting points of steel and magnesium alloy along with their immiscibility in the liquid state makes it impossible to join them using traditional welding techniques. Friction stir welding shows promising results in joining these dissimilar metals. Being a new technique, the deformation and the failure mechanism of the joint need to be investigated. In this work, a joint between AZ31 Mg alloy and DP590 steel is modeled using phenomenological crystal plasticity formulation on the mesoscale. The interface of the two materials is modeled using the cohesive zone model. A parametric study has been performed to understand the effect of grain size and interface fracture toughness as well as strength on the mechanical performance of the joint.