Synergistic Alloy Design Concept for New High-Strength Al-Mg-Si Thick Plate Alloys
43 Pages Posted: 9 Nov 2020
With the aim of fully exploiting the advantageous strength-to-weight ratio evident in Al-Mg-Si alloys, this study presents measures for increasing the yield strength of an EN AW-6082 type plate alloy. In addition to describing the thermodynamic simulation-based adjustment of age-hardenable elements (Si, Mg and Cu) and a modified artificial ageing treatment, it investigates the effects of adding a small amount of Zr. The significant strengthening induced by adding Zr is correlated with sub-grain boundary hardening in a recovered microstructure after solution annealing at 570°C, compared with the almost entirely recrystallized microstructure in an unmodified EN AW-6082 alloy. In combination with a maximum dissolvable number of age-hardenable elements and interrupted quenching, which comprises an improved heat treatment strategy for thick plates, it is seen that the yield strength can be increased by more than 40% to 411 MPa compared to conventional EN AW-6082 base material as verified by tensile testing. In the study scanning electron microscopy and scanning transmission electron microscopy were performed for microstructural characterization with a focus on particle and deformation analysis. All individual contributions which generated the superior strength are calculated and discussed in order to reveal the microstructure-property relationship.
Keywords: Aluminum alloys, Precipitation strengthening, alloy design, wrought alloys
Suggested Citation: Suggested Citation