Forming and Warm Die Quenching Process for AA7075 Aluminum Alloy and Its Application

Abstract

In order to investigate the effect of die temperature on the microstructure and mechanical properties of formed components, the forming and quenching experiments on U-shaped components of 7075 aluminum alloys at different die temperatures ranging from 25 to 350 °C were carried out. Mechanical properties of formed components were measured by Vickers hardness measurement, tensile test and electrical conductivity test. Microstructure evolution was observed by optical microscopy and scanning electron microscopy. In order to evaluate the effect of die temperature on the shape accuracy of formed components, the springback of U-shaped component was analyzed. The results showed that the Vickers hardness and tensile strength (TS) of formed components decreased with the increase in die temperature. The reduction in strength of the formed component was not obvious until die temperature reached 250 °C. The Vickers hardness and TS were 180 HV and 585 MPa, which were similar to those in T6 temper. When die temperature increased to 350 °C, the Vickers hardness and TS dropped to 93 HV and 445 MPa, respectively. As die temperature increased, the grain size increased gradually and the precipitated phase became larger. Springback angle of formed components decreased with the increase in die temperature. The die temperature should be 200 °C for forming and warm die quenching process of 7075 aluminum alloys to obtain enough strength effect and shape accuracy.