添加钛粉对铝合金搅拌摩擦焊接头晶粒结构热稳定性的影响

Effects of titanium powder addition on thermal stability of grain structure in friction stir welds of aluminum alloy

关键词:  搅拌摩擦焊  第二相颗粒  晶粒热稳定性  异常晶粒长大

Key words:  friction stir welding  second phase particle  thermal stability  abnormal grain growth

摘要:

利用搅拌摩擦焊接过程中产生的瞬时高温和强烈材料变形，通过内部开槽的方式引入铝钛混粉，使得铝与钛在焊接过程中发生剧烈原位反应，并生成金属间化合物颗粒. 探讨焊核内部的第二相分布与焊后热处理过程晶粒结构稳定性之间的关系. 结果表明,在6061铝合金中，添加钛粉的焊后热处理样品，异常晶粒区域面积大幅减小. 这说明通过引入第二相颗粒的方式，有效地抑制了焊后热处理所产生的异常晶粒长大现象；并且随着焊接道次数的增加，残留钛颗粒的分布逐渐弥散，异常晶粒长大抑制效果愈加明显，提升了焊核区域晶粒结构的热稳定性.

Abstract:

By adding a groove inside nugget zone, titanium aluminum mix powder can be introduced into friction stir welding (FSW). Intermetallic particles can be produced in situ due to high heat input and severe plastic deformation during FSW. The relationship between the thermal stability of grain structure and the second phase particles in the welds was studied and discussed. The results show that abnormal grain growth (AGG) region of heat treated samples decreased significantly with titanium powder addition as compared with that without titanium powder addition. The results further suggest that AGG after heat treatment can be restrained by introducing second phase particles into the nuggets zone. Meanwhile, it is found that with the increase of FSW passes, titanium powders are dispersed more homogeneously and the AGG region deceases, thus the thermal stability of grain structure in weld nugget is improved.