Friction stir welding (FSW) was performed on β-type Ti-15V-3Cr-3Al-3Sn alloy (Ti-15-3, mass%) plates to fabricate a sound weld joint. The microstructural and mechanical properties of the weld joint were systematically investigated in order to understand the response of the β-type titanium alloys to the FSW. The results show that a defect-free Ti-15-3 alloy weld joint can be successfully fabricated by the FSW. In the thermo-mechanically affected zone (TMAZ), the microstructural evolution is predominantly driven by discontinuous dynamic recrystallization because of the low stacking fault energy of the alloy that results in a low dislocation mobility; while in the stir zone (SZ) it is mainly promoted by continuous dynamic recrystallization due to the high temperature and high strain achieved in the SZ which improve the dislocation mobility. The material flow field within the SZ shows an incline of ~ 10° towards the advancing side (AS) around the welding direction (WD). The base material and the weld-associated zones (TMAZ and SZ) show comparable mechanical properties, which is due to the competitive effects of the dislocation density, grain diameter and grain orientation. This homogeneous mechanical property distribution makes the Ti-15-3 alloy joint preferred for industrial applications.

在β型Ti-15V-3Cr-3Al-3Sn合金（Ti-15-3，质量％）板上进行搅拌摩擦焊（FSW），以形成良好的焊接接头。为了了解β型钛合金对FSW的响应，系统地研究了焊接接头的微观结构和力学性能。结果表明，FSW可以成功地制造出无缺陷的Ti-15-3合金焊接接头。在热机械影响区（TMAZ）中，由于合金的低堆垛层错能导致位错迁移率低，主要由不连续动态再结晶驱动微观结构演变。而在搅拌区（SZ）中，由于在SZ中实现的高温和高应变而提高了位错迁移率，因此主要由连续动态重结晶促进。SZ内的材料流场显示围绕焊接方向（WD）向着前进侧（AS）倾斜〜10°。基底材料和焊接相关区域（TMAZ和SZ）显示出可比的机械性能，这是由于位错密度，晶粒直径和晶粒取向的竞争效应所致。这种均匀的机械性能分布使Ti-15-3合金接头成为工业应用的首选。