Strength and ductility optimization of HPDC AlSi8MgCuZn2 alloys by modifying pre-aging treatment

• Published in: China foundry 2024-07, Vol.21 (4), p.343-351
• Main Authors: Jiang, Yuan-hang, Zheng, Hui-ting, Liu, Fei, Zhao, Hai-dong
• Format: Article
• Language: English
• Subjects: Alloys; Engineering; Machines; Manufacturing; Materials Engineering; Mechanical properties; Metallic Materials; Processes; Research & Development; Specialty metals industry; Transmission electron microscopes
• ISSN: 1672-6421; 2365-9459
• DOI: 10.1007/s41230-024-3165-z

Considering the components produced by high pressure die casting (HPDC) process usually with ultra-large sizes and complex morphologies, high temperature solid solution treatment is not a suitable method to further improve their mechanical properties. In this study, two-stage aging treatment with different pre-aging times was designed and employed to further improve the mechanical properties of HPDC Al8SiMgCuZn alloy. The characteristics of precipitates were evaluated by a transmission electron microscope (TEM), and the precipitation strengthening mechanism was discussed. The results reveal that the strengthening is mainly contributed by the precipitation of β″ phase after two-stage aging, and the number density and size of the precipitates are significantly depended on the pre-aging time. The number density of precipitates is increased with the pre-aging time prolonged from 0 h to 4 h, and then decreases with the further increase of pre-aging time from 4 h to 6 h. The precipitates with the highest density and smallest size are observed after pre-aging for 4 h. After pre-aged at 100 °C for 4 h and then artificial aged at 200 °C for 30 min, the yield strength of 207 MPa, ultimate tensile strength of 325 MPa and elongation of 7.6% are achieved.