Effect of the Bidirectional Bending Process on the Microstucture and Mechanical Properties of AZ31B Alloy Welded Joints

Abstract

The effects of bidirectional bending on the microstructure and mechanical properties of AZ31 magnesium alloy welded joints were investigated. The microstructure and mechanical properties of welded joints with and without bidirectional bending were analyzed using optical microscopy (OM), scanning electronic microscopy (SEM), transmission electron microscopy (TEM) and tensile tests. The experimental results show that bidirectional bending proves to be an effective approach to modify the mechanical properties of an AZ31 magnesium alloy welded joint. The tensile strength of the bent joints increased from 168.4 MPa to 267.1 MPa, and the elongation increased from 6.8% to 14.8% at room temperature. Twinning is the dominant deformation mechanism, in which high density twins in the upper surfaces and lower surface of the joint were formed. The grains in the joint were refined significantly by the bidirectional bending process.