Flat friction stir spot welding of AZ31B magnesium alloy using double side adjustable tools: microstructure and mechanical properties

Abstract

A flat friction stir spot welding (FSSW) using double side adjustable tools has been developed to join magnesium alloy plates, through which sound joints bearing high mechanical performance and good surface appearance without keyhole have been successfully obtained. In this flat FSSW method, failure behaviour can only happen in the plate thickness direction due to the significantly enlarged bonded width. Sound joints can be obtained at low rotation speed; consequently, the average grain size in the tip area of the unbonded interface can be significantly decreased and the corresponding texture becomes random, giving rise to superior joint properties.

Review on joining processes of magnesium alloy sheets

“…On the basis of analyzing the existing flat FSSW processes [39,40], the flat FSSW using double side adjustable tools (Flat DSAT FSSW) was proposed by Wang et al [41], as shown in Fig. 6.…”

“…5 Different shoulder profile designs for the pinless stirring tools [38] Fig. 6 Flat DSAT FSSW process [41] on the strength of the joint. They found that the gap between sheets decreased with the increase of the feed rate, as shown in Fig.…”

“…An ultrasonically assisted SPR was proposed by Sun et al [51], including an ultrasonic vibration Fig. 7 Typical appearance of the Flat DSAT FSSW joint [41] Fig. 8 FSBR process [43] imparted on a press tool, a blank holder, a die, an upper workpiece, and a lower workpiece; the workpieces can be locally softened by the ultrasonic energy.…”