Flow Stress Behavior of Al-3.5Cu-1.0Li-0.4Mg-0.6Zn-0.3Ag Alloy under Hot Tension

Abstract

The hot deformation behavior and microstructure evolution of Al-3.5Cu-1.0Li-0.4Mg- 0.6Zn-0.3Ag aluminum lithium alloy were investigated by hot tensile tests on Gleeble-1500 thermal simulator at 480-510 °C and strain rates 0.0001-0.1 s-1. The results show that obvious flow steady-state phenomena occur during hot stretching and the main mechanism changes from dynamic recovery to dynamic recrystallization with the increase of temperature and decrease of strain rate. The constitutive equation was calculated using the true stress-strain curve obtained by the hyperbolic sinusoidal pair of deformation activation energy Q and temperature T proposed by Sellars and Tegart. The deformation heat activation energy is 226.783 KJ/mol.

Effect of Co/P micro-alloying on stress relaxation behaviour of Cu-15Ni-8Sn alloy

“…Establishing the stress relaxation kinetic equation facilitates the precise calculation of the stress relaxation behaviour of the material at any time and beginning stress, which is useful for guiding the manufacturing and application of the material. Xiao et al [27] proposed a kinetic equation for stress relaxation with reduced density of movable dislocations, the expression of which is shown in Equation ( 4):…”

“…Micro-alloying is an effective method for improving alloy stress relaxation resistance. According to the literature, Mg [20], Al [24], Fe [25], P [26], and Co [27] micro-alloying increased the stress relaxation resistance of copper alloys. Aruga's research [26] demonstrates that Cu-Ni-P alloys with low P content form low-density Ni-P clusters during annealing, which have a stronger pinning effect than solute atoms, resulting in a greater improvement in stress relaxation resistance compared to Cu-P alloys.…”

“…Aruga's research [26] demonstrates that Cu-Ni-P alloys with low P content form low-density Ni-P clusters during annealing, which have a stronger pinning effect than solute atoms, resulting in a greater improvement in stress relaxation resistance compared to Cu-P alloys. Xiao's [27] research indicates that the addition of a tiny quantity of Co to the Cu Ni Si alloy can lower the number of vacancies, restrict the slip of movable dislocations, and increase the Cu Ni Si alloy's stress relaxation resistance.…”