Work-hardening Behavior and Strength of an Al-Zn-Mg Alloy Weldment (I)

Age and Work Hardening

Abstract

An attempt has been made to improve the strength of the welded part of an AI-Zn-Mg alloy by mechanical working. Age hardening and work hardening behavior of the alloy were investigated by hardness and tensile tests, and microscopic observations. The experimental results obtained are summarized as follows.
(1) Typical age hardening was observed in ageing below 100°C and hardening in the early stage of ageing below 80°C was found to be great.
(2) Work hardening by rolling was found to occur both before and after ageing. There was a big difference in work hardening behavior between the two. The maximum hardness reached by working after ageing was higher than before ageing.
(3) There was a linear relation between hardness and tensile strength.
(4) Cold rolling before ageing has a little effect on the age hardening.
(5) Recrystallization temperature of the alloy was found to be about 250°C.