Mechanical behaviour of aircraft relevant aluminium wrought alloys at low temperatures

Abstract

The mechanical behaviour of the commercial aluminium alloys EN AW-5182, EN AW-6016 and EN AW-7021 is investigated at temperatures ranging from 298 to 77 K and strain rates from 1.7 × 10⁻³ to 6.6 × 10⁻² s⁻¹. A device that allows testing at cryogenic temperatures is developed and demonstrated, where the specimens are subject to uniaxial tensile loads. The influence of a solution heat treatment for precipitation hardenable alloys is shown. The strain-hardening coefficient is determined and mapped in terms of the experimentally investigated uniform elongation. The experimental data of tested aluminium alloys are compared with EN AW-1050A-H14, which is used as a reference. The effect of the Portevin–LeChatelier effect on ductility and strength is discussed. The Ludwik relationship is adapted to describe materials showing a Portevin–LeChatelier effect.