In recent years, die quenching process has been also proposed to the age-hardenable aluminum alloys. In the process, first the material is heat-treated to dissolve precipitates in primary α-Al matrix. Then, forming and quenching are simultaneously performed between dies with high thermal conductivity. Then, the processed aluminum alloy is artificially aged for the precipitation hardening. Thus, this technique is possible to manufacture strong products through less processes compared with conventional T6 process. In previous study [1], die quenching of a cylindrical AA2024 aluminum alloy billet with 8mm height after SHT at 773 K with WC-20mass%Co dies was not successful due to the precipitation. On the other hand, die quenching after SHT at 823 K was successfully carried out. However, the applicable reduction in height (Δh/h_0) was limited less than 5% due to crack formation. Thus, in order to apply higher reduction, two-step die motion is proposed for further compression without opening dies straightly on the same machine.
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