Numerical simulation of resistance spot welding considering phase transition effect

Al/Fe clad materials joining with Al alloy were successfully realized at intermediate temperature without flux in air by using ultrasonic-assisted brazing.Mechanical properties and microstructure of joints with Zn-Al and Al-Si filler metals were studied.The experiment showed that the oxide film of Al film at clad materials were effectively removed when Al/Fe clad materials were brazed with 5A06 alloy by using Zn-Al filler metal.Diffusion of Al film was easily controlled.There were not Fe- Al intermetallic compounds in the joins.Shear strength of joints was higher than 70 MPa when the Al film was not completely dissolved.The joints were composed of α-Al,η-Zn,Zn-Al eutectic and Zn-Al eutectoid.When Al/Fe clad materials were brazed with 1100 Al by using Al-Si filler metal,the Al film was completely dissolved in a short time.Fe-Al-Si intermetallic compounds and microcracks were observed and the shear strength was only 20 MPa.