Effects of different tempers on precipitation
hardening of 6000 series aluminium alloys
hardening of 6000 series aluminium alloys
(1. School of Mechanical Engineering, Shandong Institute of Light Industry, Ji’nan 250353, China;
2. School of Materials and Metallurgy, Northeastern University, Shenyang 110004, China)
2. School of Materials and Metallurgy, Northeastern University, Shenyang 110004, China)
Abstract: By means of Vickers hardness, mechanical property and formability tests, the effects of different tempers on precipitation hardening of 6000 series aluminium alloys for automotive body sheets were investigated. The results indicate that the short-time pre-aging at 170 ℃ makes for subsequent artificial aging precipitation hardening. With the increase of pre-aging time, the artificial aging hardenability increases. The aging hardening rate reaches the maximum when pre-aging time is up to 10 min, and then it decreases. The short-time pre-aging at 170 ℃ benefits sheets to obtain lower strength under delivery condition and consequently to improve stamping formability of automotive body sheets. The effects of different tempers on precipitation hardening are much more obvious than those of the alloying elements. It is a good treatment schedule to perform pre-aging for 5 min at 170 ℃ right after solution treatment.
Key words: T4 temper; pre-aging; artificial aging hardenability; formability