超声冲击处理对TA15钛合金板材焊缝残余应力的影响

Effect of Ultrasonic Impact Treatment on the Distribution of Residual Stress in Welds of TA15 Titanium Alloy Sheet

由于焊接过程中的温度分布不均匀,在焊接接头处会引入较大的残余应力,对焊接构件稳定性产生不利影响,超声冲击处理(UIT)则是常用的消除残余应力的方法。采用电子束焊接方式对3 mm厚TA15钛合金板材进行焊接,随后对焊接板材焊趾部位进行超声冲击处理。在光学显微镜下观察焊接接头的显微组织,利用X射线应力仪测量焊接接头的残余应力,研究超声冲击处理对焊接接头残余应力的影响。结果表明,对于TA15钛合金板材,电子束焊接接头呈"倒三角"形,焊缝处晶粒粗大;超声冲击处理能够降低焊缝表面的残余应力,并将残余拉应力转化为残余压应力。对焊趾部位超声冲击处理后,电子束焊接板材焊缝处的平均残余应力从200 MPa降低至-53 MPa。

The uneven distribution of temperature in welding process leads to the residual stress in welded joint, which is harmful to the stability of the welding structure. Ultrasonic impact treatment（UIT） is a method widely used to reduce the residual stress. In this research, the TA15 titanium alloy sheet with the thickness of 3 mm were welded by electron beam welding（EBW） method, and then conducted ultrasonic impact treatment on the weld tone. The microstructure of the welded joint after EBW welding was discussed, the residual stress before and after UIT were measured by X-ray diffraction, and the effect of UIT on the distribution of residual stress was researched. The result is that the welded joint shows＂inverted triangle＂shape after EBW of TA15 titanium alloy sheet, and grain is coarse in the weld region. UIT can not only reduce the residual stress of the welded joint, but also turn the tensile stress into compressive stress. After UIT, the average residual stress in the welded joint of EBW sheet drops from 200 MPa to -53 MPa.