Proper selection of auxiliary heat source for reducing thermal residual stresses during welding process

摘要

In this paper a method is proposed to reduce the residual stress distribution at the area close to the HAZ. Initially. the temperature distribution in an AISI 304 stainless steel, which undergoes gas metal arc welding process, is evaluated using FEM. For this purpose general purpose FEM code ABAQUS is used. The results were compared with the experimental data and a reasonable agreement is observed. Across the thickness of the weldment high temperature gradient which is a function of space and time is observed. An auxiliary moving heat source is placed on the top surface of the weldment, close to welding heat source. It was observed that if the place of auxiliary heat source and time of application are not carefully selected it may create a thermal shock and may have adverse affect on the temperature distribution. This may result in high residual stress distribution. However when the heat input for the auxiliary heat source, its location, time of application, speed and magnitude of the auxiliary heat input are carefully selected, then the temperature gradient, both spatially and temporally at area close to HAZ will reduce considerably. Even though the affect at area very close to fusion zone is trivial, our results indicate residual stresses in general may reduce due to more uniform temperature distribution.