Investigation of residual stress and post weld heat treatment of multi-pass welds by finite element method and experiments

The residual stress distribution after welding and after a post weld heat treatment have been determined by a finite element transient heat flow analysis in conjunction with a coupled thermal–mechanical analysis. To verify the numerical results, the surface residual stresses of a multi-pass butt weld were measured by the hole-drilling technique and they compared favourably with the finite element analysis predictions. The numerical analysis was applied to two multi-pass welds of thick plates used in ship construction—a 12-pass K-groove weld joint with 56 mm plate, and a nine-pass V-groove weld joint with 32 mm plate. A maximum residual stress of 316 MPa was found in the 56 mm plate, but was reduced to 39 MPa after the post weld heat treatment.