Effects of heat treatment on a novel continuous casting direct rolling 6056 aluminum alloy: cold rolling characteristics and tensile fracture properties

In this study, 6056 aluminum alloy produced through continuous casting direct rolling (CCDR) was investigated. This alloy is used in the automotive industry because of its high corrosion resistance and strength. However, the material may become embrittled as a result of excessive deformation during cold forging. Therefore, preheat treatment was employed to improve the formability of 6056 aluminum alloy. Five different preheating conditions were considered in this study: annealing (O), solution treatment (W), aging for 2 h at 195 °C after solution treatment (SPA195), aging for 2 h at 230 °C after solution treatment (SOA230), and aging for 2 h at 250 °C after solution treatment (SOA250). The results show that the over-aged specimen SOA250 exhibited the best formability and could compress 85% of the original diameter after cold rolling. However, the ductility decreased considerably after cold rolling. To increase ductility and strength, a T6 treatment was applied after cold rolling. The ductility and strength of the specimen were increased significantly, similar to the manner in which the ductility and strength of a raw material that has undergone T6 heat treatment. The CCDR 6056 aluminum alloys subjected to solution treatment and over-aging treatment exhibited good cold rolling formability, and with the subsequent T6 heat treatment, the alloys exhibited high strength and ductility. The materials can thus be used for the manufacture of automotive fasteners.