Fatigue Crack Propagation Behavior of As-Extruded AZ31B Mg Alloy Welding Joint

摘要

The fatigue crack propagation rate of an as-extruded AZ31B magnesium alloy welding joint is studied. The welding joint is parallel [T-L(H)] and vertical [L-T(H)] at the notch direction parallel to the extruded direction. Results indicate that the crack propagation direction is parallel to the extrusion direction for L-T(W); fatigue crack propagation rate is a rapid-slow process; T-L(H) is parallel to the notch direction; and L-T(H) is divided into two states (i.e., parallel to or angularly deflected towards the notch direction). Crack propagation follows an initially rapid and then subsequently slow pattern. The crack tip propagates by both transgranular and intergranular fractures. The fatigue fracture, which is brittle, consists of a quasi-cleavage.