Hot tensile behavior of an extruded Al-Zn-Mg-Cu alloy in the solid and in the semi-solid state

摘要

This is the first reported research into the tensile behavior of as-deformed Al-Zn-Mg-Cu alloy in the semi-solid state. Tensile tests of extruded 7075 aluminium alloy were carried out in the high temperature solid and semi-solid states. Based on the tensile results and microstructural examination, the tensile behavior can be divided into three stages according to the effect of liquid: one behaves in predominantly ductile character between 400 and about 520 ℃ (f_1 ～ 0.31%), one is governed by both of solid and liquid between 520 and 550 ℃ (f_1 ～ 2%), and almost completely dominated by liquid above ～550 ℃. A brittle temperature range (519-550 ℃) is proposed, in which the as-deformed Al-Zn-Mg-Cu alloy exhibits large crack probability. An equation based on ultimate tensile stress and temperature is proposed.