Effect of Groove Angles on Forming and Mechanical Properties of SK7 Steel/AZ31B Magnesium Alloy Lap Joint

doi:10.3901/JME.2024.23.262

Abstract

Abstract: A laser-induced TIG arc hybrid welding process with wire filling is proposed to weld carbon tool steel SK7 and magnesium alloy AZ31B with magnesium alloy AZ61 wire. The influence of groove angles on the forming and mechanical properties of the welded joint is studied, and the fracture behavior and performance strengthening mechanism of the joint are analyzed. The results show that the existence of the groove changes the fracture mode of the joint, eliminates the problem of weak metallurgical bonding of the steel side wall as the source of cracks, increases the metallurgical reaction area of the SK7/AZ61 interface at the groove, and improves the spreading of the welding wire on both sides of the matrix. The performance of the welded joint increases with the increase of the groove angle. When the groove angle is θ=75°, the linear load of the joint reaches 117.36 N/mm. The deflection discharge of the arc to the groove transfers the arc heat distribution area, and ensures the integrity of the back of the magnesium alloy matrix. The laser beam acting on the groove raises the metallurgical reaction temperature of the SK7/AZ61 interface. The homogeneous fusion of the AZ61/AZ31B interface and the Fe₃Al IMC generated by the high temperature metallurgical reaction of the SK7/AZ61 interface is the key to realize the reliable bonding of the joint, and the keyhole effect of the keyhole formed by the pulsed laser on the groove strengthens the joint performance.

Key words: laser-induced arc hybrid welding, dissimilar metal, lap welding, magnesium alloy, steel, groove, keyhole

CLC Number:

TG457

LANG Qiang, SONG Gang, LIU Liming. Effect of Groove Angles on Forming and Mechanical Properties of SK7 Steel/AZ31B Magnesium Alloy Lap Joint[J]. Journal of Mechanical Engineering, 2024, 60(23): 262-269.

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