Influence of Chemical Composition and Pre-deformation on the Age-Hardening Response of Al-Mg-Si Alloys

Abstract

AlMgSi (6xxx) alloys are widely used in the lightweight construction of automotive structures. In addition to light weighting, the recycling of aluminum alloys plays an important role for the optimization of the carbon footprint in the automotive industry. On the one hand, optimized AlMgSi alloys require a narrow tolerance window, both for chemistry and process parameters, and on the other hand, increasing recycling rates are a challenge to achieve a defined chemistry. In this work, the influences of alloy chemistry, grain size, pre-deformation and heat treatment parameters such as quench rate and time/temperature profiles were analyzed. 20 different AlMgSi alloys, both with and without Cu, quench rates from 500 K/min to 30,000 K/min and ageing procedures including and excluding pre-deformation and natural ageing were systematically examined. For the alloy 6082 (AlMgSiMn) yield strength values above 400 MPa and elongation to fracture values exceeding 20% were measured.