EFFECT OF PULSE PARAMETERS IN GTAW ON RESIDUAL STRESS IN AUSTENITIC STAINLESS STEEL WELDMENTS

Abstract

During welding, local non-uniform heating and subsequent cooling cause the development of complex thermal strains and stresses that finally lead to the residual stresses and distortion. Residual stresses modify the resistance to brittle fracture, fatigue strengh and stress corrosion cracking of welded part or structure. Hence, determination of magnitude and distribution of residual stresses and the effect that they may have on the component is an important consideration. The present work has been. carried out in two stages to predict the optimal pulsing parameters for the minimum residual stresses in austenitic stainless steel weldments. In the first stage, experiments were conducted to study the effect of pulsing parameters in GTAW such as of amplitude ratio, pulse frequency, duration ratio and root gap on residual stresses and for measuring the residual stresses hole drilling technique was used. In the second . stage optimization analysis was performed to find out the optimum magnitude of pulsing parameters to the least residual stresses. To reduce the number of samples to minimum, Taguchi experimental design technique was used, values of the pulsing parameters at which residual stress is minimal are obtained