轴向载荷变化对搅拌摩擦焊接过程中材料变形和温度分布的影响

EFFECT OF VARIATION OF AXIAL LOAD ON MATERIAL DEFORMATIONS AND TEMPERATURE DISTRIBUTIONS IN FRICTION STIR WELDING

采用完全热力耦合模型分析轴向载荷变化对搅拌摩擦焊接过程的影响,发现较低的轴向载荷会导致搅拌摩擦焊接无法完成.搅拌摩擦焊接构件上表面材料由于受到搅拌针和肩台旋转的作用,导致上表面材料变形程度较下表面高,材料沿焊缝中心线的变形并非严格对称,前进侧材料的变形程度较后退侧高,搅拌头轴向载荷的增加会减弱这种不对称性.搅拌摩擦焊接过程中的最高温度随轴向载荷的增加而增加,且搅拌头轴向载荷的增加会促使搅拌区附近的温度分布趋于均匀.

Fully coupled thermo-mechanical model of friction stir welding is used to analyze the effect of axial load on friction stir welding process. Results indicate that the insufficient axial load leads to the failure of the friction stir welding. The material deformation on the top surface is affected by the rotation of both the welding pin and the shoulder, which causes a larger material deformation on the top surface than that near the bottom surface. The material deformation is not symmetric to the welding line. The material deformation on the advancing side is larger than that on the retreating side. The asymmetry of the material deformation can be weakened with the increase of the axial load. The maximum temperature of the welding plate during the friction stir welding process is increased with the increase of the axial load. The temperature field near the welding tool in the nugget zone can become more homogeneous when the axial load is increased.