Finite Element Modeling for Thermal Stress and Distortion Behavior during Multi-pass Repair Welding for Cast Steel with Narrow-Long Defects

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 judge 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.