Formability and lubrication of a B-pillar in hot stamping with 6061 and 7075 aluminum alloy sheets

摘要

Aluminum alloy sheets have drawn more and more attention in recent years in the automobile industry for the purpose of weight loss and energy saving. Hot forming-quenching (HFQ) integrated process (also called hot stamping) has been developed recently for heat-treatable aluminum alloy forming to improve the formability, overcome the springback of the part. In this paper, in order to investigate the formability and lubricationof a B-pillar in hot stamping with 6061 and 7075 aluminum alloy sheets, different solution heat treatment (SHT) temperatures, SHT time and lubricants were used in the stamping experiments.The forming precision detections were also carried out after trimming. The results showed that the B-pillar wrinkled badly and cracked or even broke into pieces in cold stamping with or without lubricants.The B-pillar also cracked in hot stamping without lubricants. With the help of properlubricants, B-pillars with no crackand better surface quality could be obtained. The failure mechanisms were also explained in the present work. Besides,forming precision of most regions ranged from -1mm to 1 mm and there are still large errors in the local regions of the both ends of the B-pillar.