Effects of transformation plasticity on welding residual-stress fields in thin-walled pipes and thin plates

Abstract

Stress accumulation during cooling after single–pass butt welding is numerically studied for a pipe and a plate made of a microalloyed fine–grain C–Mn steel. The finite–element method is applied. Transformation plasticity is modelled by use of low yield stress values in the weld metal and in the heat affected zone during the final phase transformation. It is found that the stress changes induced in the pipe during the final phase transformation will partly remain at room temperature because of the low circumferential restraint during the final cooling. In the plate, however, the residual–stress field is governed mainly by the strong stress increase occurring after the final phase transformation. Stress changes induced in the plate before that event are thus hardly noticeable in the residual field.

MST/25