Metallurgical Abstracts on Light Metals and Alloys vol. 58
Concurrent Improvement of Strength, Formability and SCC Resistance of Al-Zn-Mg-Cu Alloy by Hot Stamping after Rapid Heating and Re-aging on Paint Baking Treatment
Shoichi Hirosawa*, Junmo Kim*, Tomoyoshi Maeno*, Yasushi Suzuki** and Yuuji Yabuki**
* Department of Mechanical Engineering and Materials Science, Yokohama National University, Yokohama 240-8501, Japan
** R&D Division, G-TEKT Corporation, Hamura 205-0023, Tokyo, Japan
[Published in Materials Research Proceedings, Vol. 44 (2024), pp. 227-232]
https://doi.org/10.21741/9781644903254-25
E-mail: hirosawa[at]ynu.ac.jp
Key Words: Extra super duralumin, T6 temper, High strength, Formability, Corrosion resistance
In this study, the combined application of rapid heating for hot stamping and the subsequent re-aging during a paint baking treatment was newly developed for T6-tempered A7075 Al-Zn-Mg-Cu alloy sheets. From a systematic investigation, rapid heating to 255-260°C and short-time holding for ～120 s was found to give the best combination of formability, hardness and stress corrosion cracking (SCC) resistance of the final products. In particular, re-aging treatment at 170°C for 1.2 ks was well exploited not only for further improvement of SCC resistance but also for rebound of the decreased hardness by rapid heating. Therefore, the developed three-step heat treatment is regarded as a promising approach to producing high-strength, easily formable and corrosion-resistant Al-Zn-Mg-Cu alloy parts for automobiles.
Vickers hardness and electrical conductivity of T6-tempered A7075 alloy sheets after rapid heating to various temperatures and re-aging at 170°C for 1.2 ks. The numbers within plots indicate holding times in second at a given rapid heating temperature.