预拉伸法降低异种钢焊接残余应力的作用研究

Effect of pre-tensile stress on welding residual stress filed in butt-welded dissimilar flat plates

采用热弹塑性有限元法计算了Q235钢与304不锈钢平板对接焊在不同预拉伸应力作用下的焊接残余应力场,计算结果表明,焊接残余应力呈现非对称式分布,纵向残余应力的峰值均出现在304不锈钢一侧且高于其屈服强度。预置纵向拉伸应力能显著降低纵向焊接残余应力,而且当预置拉伸应力越大时(低于屈服强度),降低焊接残余应力的效果越明显。采用红外热像仪测量了焊接过程中焊接材料表面的温度变化情况,有限元计算的结果与其符合较好。

Thermal Elasto-plastic finite element method was used to simulate the welding residual stresses in butt-welded Q235 and 304 Stainless Steel plates with different pre-tensile stresses. The simulation results indicate that the welding residual stresses present asymmetric distribution, peak of longitudinal residual stress tends to be in 304 stainless steel side. Pre-tensile stress can decrease the longitudinal residual stress significantly, and the more the pre-loads, the lower the longitudinal residual stresses. An infrared thermal imager was also applied to measure surface temperature changing of welding materials in welding process, the results are accordant with that drawn from elasto-plastic finite element measurement.