Comparative study on deformation behavior, microstructure evolution and post-forming property of an AlZnMgCu alloy in a novel warm forming process

• Published in: Journal of materials processing technology Vol. 312
• Main Authors: Zhang, Wenpei, Pang, Qiu, Lu, Junjie, Hu, Zhili
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2023
• Subjects: Al–Zn–Mg–Cu alloy; Formability; Post-forming hardness; Warm forming; Warm forming; Post-forming hardness; Formability; Al–Zn–Mg–Cu alloy
• ISSN: 0924-0136
• DOI: 10.1016/j.jmatprotec.2022.117854

Hot forming technique has served as a solution to overcome the poor formability of aluminum alloys at room temperature (RT). However, it also causes high energy consumption and a prolonged period of processing cycle. Apart from hot forming, warm forming is an alternative method for improving formability. In this work, warm forming processes for aluminum alloys were classified into two categories, including a conventional warm forming of T6-temper alloy (WF-T6) and a novel pre-hardening warm forming (PHF) process. Based on an Al–Zn–Mg–Cu alloy, warm tensile tests and Erichsen tests were performed to investigate the flow behavior and drawability, and Vickers hardness tests were used to evaluate the post-forming property. Superior formability and post-forming hardness were obtained at 200 ℃ in PHF process compared with WF-T6 process, which achieved a drawability 15% higher than that of O-temper alloy at RT, and a post-forming hardness superior to that of T6-temper blank. Against common sense, due to the particularity of the phase transition mechanism in PHF process, the temperature at 180 ℃ exhibited lower yield flow stress and post-forming hardness than 200 ℃. In addition, it is interesting to find that the inducement to the loss of hardness after forming at 250 ℃ was absolutely different in these two processes. Electron backscatter diffraction (EBSD), scanning electron microscope (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) tests were employed to characterize the microstructure evolution, and the engineering potential of these two processes was discussed. [Display omitted]