Prevention of build up of residual stresses in welds during welding and subsequent reheat cycles

Abstract

A process is described in which a weld is produced without residual stresses; or with residual stresses reduced to a low value. Stress cycles of low value at low frequency are applied in the longitudinal direction of the weld by means of an air operated vibrator during welding. Application of stress cycles may be continued after welding, during or after reheating which may be applied to the solidified weld. Stress cycles are applied at high temperature when the weld metal is in a molten state, semi-solid state and solidified state, and thus brings about reduction in dislocation density in solidified crystals. Stress exists at each dislocation and since the dislocation density is reduced, reduction in residual stress takes place thereby eliminating the need for additional stress relieving operations. Since stress cycles are applied during welding, gases in molten metal are driven out and porosity in the solidified weld is reduced.

Dependencies are inferred from the claim text.