不锈钢薄板激光搭接焊残余应力测量方法对比研究

Comparison of residual stress determination methods for laser lap welding of stainless steel sheet

为了研究不锈钢车体非熔透激光搭接焊中的残余应力,采用2 mm+2 mm厚SUS 301L不锈钢板冷轧板进行了CO_2激光搭接焊试验,选择压痕应变法、全释放应变法和X射线衍射法测量接头中的残余应力。结果表明,压痕应变法测量的纵向峰值应力为237 MPa,横向为124 MPa,测量结果为1 mm2区域近表面的平均残余应力;全释放应变法测量得到的纵向、横向应力峰值分别为155 MPa和55 MPa,测量结果为5 mm×5 mm整个解剖试样的平均残余应力;X射线衍射法测量的纵向、横向应力峰值分别为344 MPa和163 MPa,测量结果为1~2 mm区域表层中的平均残余应力,且误差范围较大。

In order to research residual stress for non-penetration laser lap welding of stainless steel plate,the 2 mm + 2 mm cold rolling SUS301 L stainless steel plates were welded by axial flow CO_2 laser. The indentation strain-gage method, sectioning-relaxation strain-gage method and X-ray diffraction method were used to measure residual stress in the lap welded joints. The results from the indentation strain-gage method show that the peak value of longitudinal residual stress is 237 MPa, the maximum transverse residual stress is 124 MPa, and all the residual stress values reflect an average around 2 mm near the surface layer. The results from the sectioning-relaxation method show that the peak value of longitudinal residual stress is 155 MPa, the transverse residual stress is 55 MPa, and all the residual stresses are an average in the sample whole section with 5 mm × 5 mm × 2 mm. The results from X-ray diffraction method show that the maximum longitudinal residual stress value is344 MPa,the transverse residual stress peak value is 163 MPa, and all the residual stresses are an average in the circle of 1~2 mm in diameter near the surface layer. Comparatively speaking, the error from X-ray method is higher than the other methods due to the obvious texture and coarse grains.