Friction stir-induced brazing of Al/Mg lap joints with and without Zn interlayer

Abstract

The interfacial structure and mechanical properties of Al/Mg joints with and without Zn interlayer by friction stir-induced brazing bond have been investigated. The results revealed that the formation of brittle Al-Mg intermetallics could be effectively suppressed by the addition of Zn interlayer and using appropriate welding parameters, which were replaced by α(Mg)+Mg-Zn and Al-Mg-Zn intermetallic. When rotation speed was further increased, Al-Mg intermetallics were formed again at the interface. The shear strength of Al/Mg joints with Zn interlayer was improved by up to ∼ 25% in comparison with those of the joints without Zn interlayer. A mixture of ductility and cleavage fracture occurred on fracture surfaces of Zn-added joints which was different from the cleavage fracture feature of the direct joints.

Improving the Mechanical Property of Dissimilar Al/Mg Zn‐Added Ultrasound‐Assisted Friction Stir Lap Welding Joint by Back Propagation Neural Network–Gray Wolf Optimization Algorithm

“…Compared with the conventional dissimilar Al/Mg FSLW, the assistance processes of the Zn interlayer and the ultrasound are beneficial to improving the joint quality. For comparison with the reported results, a ratio (N/mm) of the maximum tensile shear load to the width of tensile specimen is adopted in this study as a conversion criterion for tensile shear strength according to Liu et al The tensile shear strength of the joint under the executable optimal process parameters combination is 11.8% larger than that of the reported optimal joint, as shown in Figure . The fracture location of the joint in this study is shown in Figure a.…”

“…Weakening the adverse effects of IMCs is an important approach to improve the quality of dissimilar Al/Mg FSLW joint. Gan et al reported that the Al‐Mg IMCs could be avoided by a Zn barrier layer during dissimilar Al/Mg friction stir‐induced diffusion bonding. Eutectic reactions of L→Mg‐Zn and L→Mg‐Zn+Al‐Mg‐Zn respectively occur at the temperatures of 480 and 340 °C during the solidification process according to Al‐Mg‐Zn three phase diagram .…”

“…Therefore, the Mg‐Zn and Al‐Mg‐Zn IMCs are preferentially formed before the Al‐Mg IMCs. From the viewpoints of weakening the adverse effect of IMCs, the Mg‐Zn and Al‐Mg‐Zn IMCs excel the Al‐Mg IMCs due to relatively small hardness . However, these two IMCs still deteriorate the strength of joint.…”

Friction Stir Spot Welding-Brazing of Al and Hot-Dip Aluminized Ti Alloy with Zn Interlayer

“…Recently, friction stir brazing (FSSB) has been developed by using a pinless tool and adding brazing filler metal to induce metallurgical reaction at the interface with the aid of friction heat and forging pressure, instead of plastic flow [22]. This technique has successfully introduced a brazing zone in dissimilar joints of steel/Al [26], Cu/Al [27], and Al /Mg [28], while FSSB of Al and Ti alloys is yet to be reported.This work aims to find an effective approach to improve the joining area of the Al/Ti joint by combining FSSW and FSSB. Zinc (Zn) is an optional filler for FSSB of Al alloys as a result of its low melting point (420 • C), high solubility in Al, as well as absence of formation of IMCs in the Al-Zn alloying system [29][30][31][32].…”

“…Recently, friction stir brazing (FSSB) has been developed by using a pinless tool and adding brazing filler metal to induce metallurgical reaction at the interface with the aid of friction heat and forging pressure, instead of plastic flow [22]. This technique has successfully introduced a brazing zone in dissimilar joints of steel/Al [26], Cu/Al [27], and Al /Mg [28], while FSSB of Al and Ti alloys is yet to be reported.…”