Effect of solubilisation on the high-temperature formability of AA6016 sheets

In the recent years, forming of high strength aluminum alloys sheets at elevated temperatures has gained a renewed interest for the manufacture of parts of the car body-in-white and chassis on the basis of the more and more stringent requirements in terms of mass saving and fuel consumption reduction on one hand, and increase of passengers’ safety on the other. Being these alloys usually characterized by reduced formability when formed at room temperature, a number of scientific studies are now focusing on different means to enhance their formability limits. One possibility is represented by the hot stamping, during which the blank is heated at elevated temperature and simultaneously formed and quenched inside cooled dies [1-2]. The paper will investigate the deformation behaviour of AA6016 sheets in a range of temperatures and strain rates typical of hot stamping by means of hot tensile tests and mechanical and microstructural analyses after deformation. Since the as-delivered condition of the blanks was the T4 treatment, the blanks were subjected to two different thermal cycles before testing: one implying the material solubilisation and subsequent cooling and deformation at the testing temperature, and the other without any solubilisation. The influence of the solubilisation on the material flow stress, true strain at fracture, microstructural and failure features, and post-forming mechanical characteristics will be highlighted. The optimal combination of process parameters assuring the best formability will be identified.