搅拌摩擦焊焊缝表面弧形纹形成模型

建立了搅拌摩擦焊接过程中焊缝表面弧形纹形成过程模型，解释了弧形纹弧峰、弧谷的形成原因。焊接过程中，轴肩与母材表面间所形成的软化层沿着搅拌头的转动方向缓缓向轴肩后方流动。形成了软化薄层，并不断增厚。当轴肩与流动到轴肩后侧的软化层两者界面处的分子间吸附力不足以带动软化层整体向前运动时，软化层外侧的薄层与轴肩脱离，并在随后的冷却过程中硬化而形成弧峰。上述行为在搅拌摩擦焊接过程中反复发生，导致相邻弧峰间产生一凹陷，形成弧谷。焊缝表面相邻弧峰间距与搅拌头行走速度成正比，与搅拌头的转速、轴肩／母材间的摩擦系数成反比。

Process model of arc corrugation on friction-stir weld

This paper established a process model of arc corrugationon friction-stir weld,which explained the forming reason of arc crest andtrough. The softened layer on the interface between shoulder and parentmaterial flew slowly to the back of shoulder in the direction of tool rotationduring welding,resulting in softened material accumulating behind shoul-der. When the accumulated layer was so thick that the folium outside thelayer lagged and formed arc corrugation during cooling, resulting from theintermolecular attraction between shoulder and softened material being in-sufficient to drag all softened material. The above process occurred con-stantly,resulting in arc trough between two adjacent arc crest. The spacebetween two adjacent are crest depended on tool rotational speed, travelspeed and shoulder/parent material interfacial friction coefficient.