Control of residual stresses affecting fatigue life of pulsed current gas-metal-arc weld of high-strength aluminum alloy

Abstract

The influence of pulse parameters on residual stresses of the gas-metal-arc (GMA) weld of a 10-mm-thick extruded section of high-strength Al-Zn-Mg alloy has been analyzed. The role of pulse parameters affecting the residual stresses of the weld joint has been studied by considering a summarized influence of pulse parameters defined by a dimensionless factor ϕ=[(I b /I p ) ft b ]. The reason for the variation in residual stresses of the weld joint with a change in ϕ under different mean currents (I m ) has been studied by correlating the extent of weld metal deposition and weld size with the ϕ. It is observed that the increase of ϕ reduces the longitudinal and transverse stresses of the weld joint. The nature of variation in residual stresses of the weld joint with ϕ shows an agreement to the trend of variation in its size with ϕ. In conformation of an earlier work, it is proposed that the use of a pulsed current gas-metal-arc welding (GMAW) at proper pulse parameters giving desired ϕ may produce a weld joint having comparatively lower residual stresses with improved fatigue life than that of the weld joint produced by conventional GMAW process through its influence on weld size.