Thermo-Mechanical Behaviour of Structural Lightweight Alloys

Abstract

The need to reduce the ecological footprint of (water, land, air) vehicles in this era of climate change requires pushing the limits in the development of lightweight structures and materials. This requires a thorough understanding of their thermo-mechanical behaviour at several stages of the production chain. Moreover, during service, the response of lightweight alloys under the simultaneous influence of mechanical loads and temperature can determine the lifetime and performance of a multitude of structural components The present Special Issue, formed by eight original research articles, is dedicated to disseminating current efforts around the globe aiming at advancing in the understanding of the thermo-mechanical behaviour of structural lightweight alloys under processing or service conditions. The two most prominent families of lightweight metals, namely aluminium and magnesium alloys, are represented with five and three contributions, respectively. The work by Poletti et al. [1] deals with the evolution of the microstructure of an AA6082 alloy during thermo-mechanical processing. The production of wrought aluminium alloys usually comprises successive thermo-mechanical steps that involve complex physical phenomena at the microstructural level. Based on flow data and thorough microstructural observations they propose a physically-based constitutive model that can reproduce the behaviour of the alloys during cold and hot working over a wide range of strain rates. The same alloy was studied in [2] by Wiechmann et al. In this case, the authors studied the evolution of the microstructure and the mechanical behaviour of MIG welded joints applying several complementary ex situ and in situ experimental techniques. The results obtained in this work are a step forward to understand the influence of welding heat on the softening behaviour of this alloy. Also dealing with wrought Al alloys, although in a different alloy system, the work by Kowalski et al. [3] investigates the effect of low-temperature thermomechanical treatment (LTTT) on the microstructure, mechanical behaviour and corrosion resistance of a 7000 series AlZn6Mg alloy. Interestingly, they report conditions for LTTT which render better mechanical performance than conventional heat treatments. Moreover, they show that the electrochemical corrosion resistance of the alloy decreases with increasing plastic deformation, while, on the other hand, stress corrosion resistance is improved. Bugelnig et al. [4] report on the effect of Ni concentration on the damage accumulation during high temperature tensile deformation of AlSi12Cu4Ni2-3 piston alloys. Using 3D and 4D synchrotron imaging the authors show that interconnecting branches within highly interconnected brittle networks of aluminides determine the damage evolution and ductility in these alloys. A load partition model that considers the loss of interconnecting branches within the rigid networks owing to damage is proposed to rationalize the experimental observations. The last contribution dealing with Al allo...