针对铸钢件上窄长缺陷的补焊过程建立了三维瞬态热力耦合模型；采用体积热源模型描述焊接热源输入,考虑了铸钢件内部的导热及其与环境之间的对流换热作用,以及熔化与凝固过程中的潜热；采用Mises准则判断材料的弹塑性状态,认为材料近似服从双线性等向强化的本构模型,并采用生死单元法处理增材过程；对铸钢件三道补焊过程的热应力及变形行为进行了有限元模拟,并用参考文献的结果进行了验证。结果表明：由于热源对基材的预热作用,第二道和第三道堆焊金属的峰值温度比第一道堆焊金属的略有升高；补焊过程中的最大应力可达到300 MPa,接近钢的室温屈服强度,出现在焊缝表面和热影响区附近；由于基材对堆焊金属的强约束作用,铸钢件在补焊过程中的整体变形较小。%A transient 3D thermo-mechanical coupling model was established for the repair welding process of cast steel.Volumetric heat source was adopted to describe welding heat source input,conduct heat transfer within the cast steel and the convection heat transfer between the cast steel and the environment were considered,and the latent heat during melting and solidification were also considered.Mises yield criterion was used to j udge the plastic or elasticity state,the constitutive relation of the material was treated as double-linear,and the addition of the material was treated with the birth-to-death element method.Finite element modeling was made on thermal stress and distortion behavior during three pass repair welding.The results from reference was used to verify the validity of simulated results.The results indicate,because preheating effects of the heat source,the maximum temperature of deposited metal of 2nd and 3rd passes was a little more than 1st pass;the maximum equivalent stress arrived at about 300 MPa,near to the yield stress of the cast steel at room temperature,located at the surface of weld seam and near heat affected zone;Because of the strong constrain effect of the base metal on the deposited metal,the deformation of the cast steel was small in whole during repair welding.
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