On fatigue life improvement using low transformation temperature weld material.

The process of welding often produces high tensile residual stresses. By using low transformation temperature welding wire, these high tensile residual stresses can be drastically reduced, or transformed into compressive residual stresses. This in tum increases the fatigue life of the welded structure. In this study, the transformation strain of candidate welding materials has been obtained and compared to that of conventional welding wire. Fatigue specimens have then been fabricated with these welding materials and the residual stresses obtained. It has been found that the removal of tensile residual stresses has a greater effect on the improvement of the fatigue life than on the imposition of compressive residual stresses. Differences in residual stresses between specimens have been found to concentrate in the surface near the weld toe.