超声辅助搅拌摩擦焊对焊缝残余应力的影响

Effect of ultrasonic assisted friction stir welding on residual stress of welded joint

为了研究超声辅助搅拌摩擦焊对焊缝残余应力的影响,试验应用20 kHz的超声波辅助搅拌摩擦焊焊接了1.8 mm厚2024-T4铝合金,焊后应用X射线衍射法对焊缝的表面残余应力进行了测量,并与相同参数、工艺条件下搅拌摩擦焊残余应力进行对比。结果表明:转速1 200 r/min、焊速160 mm/min时,超声辅助搅拌摩擦焊纵向残余应力比搅拌摩擦焊平均降低38 MPa(降低28.5%)。超声辅助搅拌摩擦焊沿焊缝方向各点纵向残余应力分布更加均匀化,波动量降低。超声辅助搅拌摩擦焊对焊缝横向残余应力影响很小,应力水平与搅拌摩擦焊相当。在相同转速下,随着焊接速度的提高,焊缝的纵向残余应力也随之提高。

To investigate the effect of ultrasonic assisted friction stir welding （UAFSW） on residual stress of weld line, 1.8 mm thick 2024-T4 aluminum alloy plates were welded by UAFSW with 20 kHz ultrasonic, and the residual stress of UAFSW was measured by X-ray diffraction and compared with that of friction stir welding （FSW） under the same process parameters. The results indicate that when the stirring rate is 1 200 r/min and the welding speed is 160 mm/min, the longitudinal residual stress of UAFSW reduces 38 MPa compared with that of FSW on average, which is decreased by 28.5%. And the longitudinal residual stress along the weld line of UAFSW is much more even than that of FSW. UASFW has small impact on the transverse residual stress, which is nearly equal to that of FSW. The transverse residual stress increases as the welding speed increasing at a constant rotation rate.