强度和线膨胀系数匹配对焊接残余应力的影响规律

Influence of Matching Weld Strength with Its Thermal Expansion Coefficient on the Residual Stress of Welded Joint

本文采用热弹塑性有限元法研究了焊缝强度匹配和线膨胀系数匹配对焊接动态应力以及残余应力分布的影响规律。计算结果表明,在相同母材(σ_s^p=400MPa)以及等胀匹配条件下(即焊缝线膨胀系数α~w=母材线膨胀系数α~p),焊缝中心纵向残余应力σ_x为拉应力,其值总是接近于焊缝金属屈服强度σ_s^w,且屈服强度的高低不会改变拉应力的性质。在等强匹配条件下(σ_s^w=σ_s^p),焊缝中心σ_x随焊缝线膨胀系数α~w的降低而降低,其性质有可能由于α~w的不断降低而由拉应力转变为压应力。而当α~w高于α~p时,焊缝中心达到σ_s^w后变化不大。

In this paper, transient stress history and residual stress distributin of welded joints are investigated by using the method of thermal elasto-plastic finite element analysis. Results of the computation show that in the weld joint longitudinal residual tensile stress in the weld center is always close to the yield strength of the weld metal when the same parent metal ( 400MPa) metal and TEC evenmatched joint are used and that the change of of value doesn't change the nature of the residual tensile stress. However, in the same parent metal and strength evenmatched joint, the residual stress ox in the weld center changes with TEC of the Weld metal, when the TEC of the weld metal becomes lower than that of the parent metal, the residual stress ox also gets lower, and its tensile stress in the weld center possibly becomes into compressive stress, but when the TEC of the weld metal becomes higher than that of parent metal, the stress ox could become as high as and then changes a little.