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.

中文翻译：

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AZ31B镁合金平面搅拌摩擦点焊双面可调刀具：显微组织和力学性能

开发了一种使用双面可调工具的平面搅拌摩擦点焊（FSSW）来连接镁合金板，通过它成功地获得了具有高机械性能和良好表面外观的无小孔的良好接头。在这种平面 FSSW 方法中，由于粘结宽度显着扩大，失效行为只能发生在板厚方向。低转速下可获得良好的接头；因此，未结合界面尖端区域的平均晶粒尺寸可以显着减小，相应的织构变得随机，从而产生优异的接头性能。