Hot Stamping of a B-Pillar Outer from High Strength Aluminum Sheet AA7075

This work demonstrates the feasibility of hot stamping a B-pillar outer panel from aluminum alloy 7075. AA7075 is characterized by a high strength to weight ratio with yield strengths comparable to those of DP and TRIP advanced high strength steels. Applications using AA7075 have typically been limited to the aerospace industry due to the high variable cost associated with forming and joining of these materials. A primary key to implementation in the automotive industry is the development of metal forming methods that produce non-compromised stamped parts at automotive manufacturing volumes and costs. This work explores the feasibility of die quenching a hot blank within a cold die as a means of delivering high strength aluminum sheet parts. A die made from kirksite was used to evaluate the hot stamping process for a B-pillar outer. After the forming/quenching operation, the parts were subjected to an artificial aging process to regain the properties of the T6-temper. The results show that hot stamping, followed by an adequate artificial aging treatment, produces a high strength component with material properties equivalent to the as-received T6 properties delivered by the material sheet supplier. In addition, the hot stamped B-pillar component demonstrated limited springback with a high level of dimensional accuracy.