Effect of pre-heat treatment conditions on aging behavior of the heat-affected zone in Al-Zn-Mg alloy welds

Abstract

Hardness measurements, X-ray small angle scattering methods and transmission electron microscopy were applied. The structure of the base material before welding has an influence on the post-weld aging behavior of the heat-affected zone in the Al-Zn-Mg alloy weld. Considerable softening occurs in the weld heat-affected zone of the alloy which has been over-aged before welding. This softening is attributed to coarsening of precipitates in the weld thermal cycle. The width of the heat-affected zone in the Al-Zn-Mg alloy weld is thinner as the base material has been aged before welding at elevated temperature and for prolonged time.