Effects of nano-SiC particles on the FSSW welded AZ31 magnesium alloy joints

Abstract

The microstructure of nano-SiC enhancing friction stir spot welding (FSSW) joint with dwell time of 3 s was characterised by an onion ring structure which consisted of alternate SiC-free zones and SiC-rich zones where SiC particles refined the grains. However, onion ring structure disappeared and SiC particles dispersed homogeneously when dwell time was 5 s. The microhardness of stir zone (SZ) and tensile shear load of SiC enhancing FSSW joint were higher than those of conventional FSSW joints. After heat treatment at 200°C for an hour, grains of the SZ grew substantially and coursed reduction in mechanical properties of joints, while grain size of SZ and tensile shear load of SiC enhancing joint was invariant but the microhardness of SZ increased.

Numerical Simulation and Experimental Study on the TIG (A-TIG) Welding of Dissimilar Magnesium Alloys

“…Figure 21 shows the velocity field distribution of the cross-section of the molten pool perpendicular to the welding direction during A-TIG welding of dissimilar magnesium alloys AZ61 and AM60. According to the studies of Xie et al [ 24 ] and Wu et al [ 25 ], during A-TIG welding with activating flux, the increase of penetration depth is mainly due to the influence of surface tension. Furthermore, the positive and negative temperature gradient has a great impact on the depth of the molten pool.…”

Assessment of dissimilar joining between metal and polymer hybrid structure with different joining processes

“…In this study the improvement of strength is attributed with the fine grain size. 121 Song et al 122 investigated the influence of plunge speed on friction spot welding of AA6061-T6 sheets, 2,4,6,8 and 10 mm/min are the range of selected plunge speed. Results clearly shows that tensile shear load increases upto 6mm/ min and remains constant.…”

Review on joining processes of magnesium alloy sheets

“…Moreover, the effect of liquid nitrogen on the tool and die is also unknown. In addition to the liquid nitrogen cooling that can enhance the microhardness of the magnesium alloys FSSW joint, the joint enhancement can also be achieved by introducing the nano-SiC into the FSSW process in the research of Wu et al [29], the nano-SiC particle enhancing FSSW (NPE-FSSW) was proposed, and the nano-SiC particles with an average size of 40 nm were introduced to a rectangular hole of the top sheet, as shown in Fig. 2.…”

“…1 The FSSW process [22] Fig. 2 Schematic illustration of NPE-FSSW process [29] the NPE-FSSW, which increased the process flow, made the process less efficient and was unsuitable for large-scale automated production.…”