Abstract
The poor formability of 7xxx series aluminium alloys represents the major limit to their actual use for automotive and aerospace applications. In the present study, the forming temperature effect on the mechanical, corrosion and anodization behaviours of the AA7075-T6 alloy is investigated. To this purpose, tensile tests at different temperatures, ranging from −100 to 300°C, were carried out at different rolling directions. A 6.6% increase of the ultimate tensile strength and a 28.6% increase of the uniform elongation were registered for the specimens deformed at the lowest temperature compared to highest ones. Further, the corrosion resistance of specimens deformed at ultimate tensile strength before and after anodization was increased of 85% and 95%, respectively, compared to the specimens deformed at 300°C. It was demonstrated that high deformation temperatures led to the coalescence of particles and precipitates as well as the decrease of dislocation density, which, in turn, decreased the mechanical and corrosion performances. On the contrary, the deformation temperature of −100°C was found to be the ideal one able to shorten the manufacturing process chain and improve material formability and durability during its in-service life.
Highlights
The poor formability of 7xxx series aluminium alloys represents the major limit to their actual use for automotive and aerospace applications
As regards the influence of the rolling direction, the specimens cut at 90° show a higher flow stress for temperatures lower than 100°C than the ones cut along 0° and 45°
A 6.6% and 28.6% increase of ultimate tensile strength (UTS) and εneck was registered for the specimens tested at the lowest temperature with the respect to the ones tested at the highest temperature
Summary
The poor formability of 7xxx series aluminium alloys represents the major limit to their actual use for automotive and aerospace applications. 7xxx series aluminium alloys are characterized by a very attractive combination of low density, high specific strength and corrosion resistance They are more and more used for lightweight structural components in the automotive and aerospace industries, in which weight savings for reduced fuel consumption and exhaust emissions are mandatory [1]. Their adoption for manufacturing sheet components is greatly limited by their scarce formability [2], and rapid degradation when exposed to the in-service environment that deteriorates their mechanical properties [3] To this aim, the anodic oxidation process is usually applied to build a robust oxide layer on these alloys surface, in order of improving their.
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