Microstructure and mechanical properties of AZ31B magnesium alloy/304 stainless steel resistance spot weld joint with high entropy alloy powder

Abstract

In order to obtain high quality AZ31B/stainless steel resistance spot welded joints, the FeCoNiCrMn high entropy alloy was used as the interlayer. The reaction-diffusion behavior of the transition zone and the base material on both sides was analyzed, and the joint performance and the welding process were investigated. The results show that the transition zone consists of FeCoNiCrMn particles which successfully connects two base materials of AZ31B and stainless steel. The interface near AZ31B is mainly Fe4Al13 intermetallic compounds generated by the reaction around the particles; while the boundary of stainless steel is mainly composed of (Fe, Ni) solid solution and Fe4Al13 intermetallic compounds. The tensile shear load F shows a tendency that increases first and then decreases with the increase of welding current I, welding force P, and the prolongation of welding time t. The tensile shear load of the added high entropy alloy magnesium/steel spot welded joints are above 3.2 kN in the test process range of 18.2-22.5 kA, 15-35 cycle, and 2.0-10.6 kN, and the maximum tensile shear load is 5.605 kN, which is 397% higher than that of Mg/steel spot welded joints without high entropy alloy. A large number of (Fe, Ni) solid solution are formed in the high entropy alloy transition layer, which reduces the generation of Fe4Al13 brittle intermetallic compounds and effectively improves the mechanical properties of the joint.

Keywords

• az31b magnesium alloy
• 304 stainless steel
• resistance spot welding
• high entropy alloy
• shear load