Mechanical properties of aluminium weldments FE simulations

Abstract

The low density of aluminium, resulting in a high strength-to-weight ratio, makes it a favourable material in several industries. Additionally, increasing use of aluminium will contribute to achieve more sustainable and greener structures. Even if aluminium has found its application in a long range of products, the market could have been much larger, provided that the strength loss in aluminium weldments could be avoided. The area impacted by the heat input from the welding process is termed as the heat affected zone (HAZ). For high-strength alloys joined by fusion welding, the HAZ is typically 30 to 50 percent weaker than the base material. Therefore, the strength of the structure is strongly limited by the strength of this soft zone, causing localization of plastic strain to occur in heat affected zone. Hence, the structural ductility severely decreases due to the highly localized strain in the HAZ. Innovative solutions to eliminate the strength reduction would be a "game-changer" for use of aluminium in structures. A purely numerical procedure is presented in this study with the aim to study how the temperature of the plates being welded (active cooling) and interpass temperature affects the strength and width of the HAZ. In addition, the effect of heat input is assessed. The hardness profiles with cooling show a significant effect on the width of the soft zone. It is seen that the width of the HAZ decreases continuously with decreasing interpass temperature in the numerical analysis. The reduction in thermal affection produced by lower interpass temperature have seen to minimizes the over-aging effect of the base metal.