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Study on hot stamping process of aw-7921-t4 alloy sheet

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Document pages: 10 pages

Abstract: Compared with aw-5xxx and aw-6xxx alloys, aw-7xxx alloy has higher strength, so it is considered to have greater lightweight potential in the automotive industry. However, due to its low formability, the forming process is still in the development stage. In this paper, a forming process called hot stamping is studied. Firstly, the hot tensile test of aw-7xxx alloy (i.e. aw-7921) was carried out at the temperature between 350 ° C and 475 ° C to measure the strength and formability. The formability increases with the increase of temperature and is sensitive to strain rate. Dynamic recovery is considered to be a common reason for improving formability. However, different methods are used to check the receiving state and the precipitation state after hot stampingntial scanning calorimetry (DSC), the dissolution of precipitates was also believed to contribute to this increase in formability. Following solution heat treatment there was no precipitation during cooling across the cooling rates investigated (5–10°C s). Samples taken from parts hot stamped at 10 and 20 mm s−1 had similar yield strengths. A 3-step paint baking heat treatment yielded a higher postpaint baking strength than a single step treatment.

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