Effect of plunge depth on microstructure and mechanical properties of FSW lap joint between aluminum alloy and nickel-base alloy

Abstract

Reports about dissimilar joining of aluminum alloy and nickel base alloy are rare. The friction stir welding (FSW) technique reveals advantages over fusion welding in terms of dissimilar jointing. In the present research, FSW was employed to produce lap joints of aluminum alloy (2A70) and nickel-base alloy (Inconel 600) with various plunge depths (0–0.5 mm) under a given welding and rotation speed (1200 rpm, 40 mm/min). Macrographs were taken and the microstructure of the cross-section of the lap joints was investigated by optical microscopy and scanning electron microscopy. A fine-grained zone was discovered on both sides of the interface. A thin Al3Ni interlayer was generated at the interface. The plunge depth has a vital influence on the joint strength. The lap joint failed at a very low load when the pin did not reach the nickel alloy surface, while the maximum shear strength of the lap joint was obtained under a plunge depth of 0.3 mm and reached 7.9 KN.