Effect of Transformation on Residual Stress in Welding. Stress Releasement by Transformation Superplasticity(Part 5).

Abstract

Residual stress and angular distorsion are very important problems in welding design and fabrication. In the previous reports it was shown that the materials with a martensitic transformation at low temperature were effective to reduce the anguler distorsion and deformation in welding.In this report the effects of transformation on residual stresses were examined. The results are shown as follows;(1) Residual stresses are closely related to transformation (transformation expansion and superplasticitiy) in welding and compressive stresses were measured at the surface of weld metal for a few welding electrodes with the low transformation temperature.(2) The materials with the transformation at low temperature are effective to reduce the residual stress in welding. In this study, the residual stresses of the weld metal with the transformation temperature of 200-300°C showed the minimun value.(3) It is possible to reduce both the residual stress and anguler distorsion in welding at the same time by use of the welding material with transformation at low temperature.