不同过程参数对搅拌摩擦焊接中材料流动以及残余应力分布的影响

通过有限元法建立了搅拌摩擦焊接的二维模型,并研究了不同工艺参数下搅拌摩擦焊接过程中材料的流动以及残余应力的分布。在搅拌摩擦焊接过程中,切向流动构成了材料流动的主要形式,并且材料流动最为剧烈的区域发生在后退侧。在材料的切向流动中,材料的流动方向不是单一的,可能会形成漩涡。搅拌头平移速度和转速的增加,都能使材料在后退侧的流动变得更为剧烈,但是在材料流动速度较小的区域,参数的改变对材料流动的影响很小。纵向残余应力的最大值始终发生在热影响区的边界,并且纵向残余应力在靠近焊缝中心线的附近一般为正值,而在靠近焊接构件边界的地方,残余应力则表现为负值。纵向残余应力的最大值随着搅拌头平移速度的增加而有所增加,但是搅拌头转速的变化对纵向残余应力的分布影响不大。

EFFECT OF PROCESS PARAMETERS ON MATERIAL FLOW AND RESIDUAL STRESS IN FRICTION STIR WELDING

A two-dimensional model of friction stir welding is established to study the distributions of the longitudinal residual stress and the material flow under different process parameters. In the friction stir welding process, the tangent flow constitutes the major part in material flow. The faster material flow occurs on the retreating side. In the tangent flow, the flow direction is not simple and there may exist a swirl in the material flow on the advancing side. With the increase of the translational velocity and the angular velocity of the pin, the flow becomes faster on the retreating side. But in the region where the material velocity is smaller, the effect of the variation of the process parameters is not clear. The maximum longitudinal residual stress occurs on the boundary of the heat affected zone and the longitudinal residual stress is positive near the welding line but negative near the boundaries of the welded plate. The maximum longitudinal residual stress can be increased with the argument of the translational velocity of the pin. But the change of the angular velocity of the pin does not affect the longitudinal residual stress significantly.