Microstructure evolution and mechanical properties of ZK60 magnesium alloy produced by SSTT and RAP route in semi-solid state
(1. No.59 Institute of China Ordnance Industry, Chongqing 400039, China;
2. Chang’an Automobile Stock Co., Ltd, Chongqing 401120, China)
2. Chang’an Automobile Stock Co., Ltd, Chongqing 401120, China)
Abstract: The microstructure evolution and mechanical properties of a ZK60 magnesium alloy produced by the semi-solid thermal transformation (SSTT) route and the recrystallization and partial melting (RAP) route were studied, respectively. The microstructure evolution during partial remelting was studied at different temperatures for different time. The tensile mechanical properties of thixoformed components by the two routes at room temperature were examined. The results show that coalescence is dominant in the SSTT alloy and Ostwald ripening is dominant in the RAP alloy. Compared with the SSTT route, the RAP route can produce finer semi-solid microstructure under the similar isothermal holding condition. The microstructure of the RAP alloy is much more spheroidized compared with the SSTT alloy. Thixoforming for the ZK60 magnesium alloy produced by the SSTT and RAP route results in successful filling of the die, and the thixoforming process improves the mechanical properties of ZK60 magnesium alloy. The RAP alloy shows significantly advantageous mechanical properties over that of the SSTT alloy.
Key words: ZK60 magnesium alloy; semi-solid thermal transformation (SSTT); recrystallization and partial melting (RAP) route; microstructure evolution; mechanical properties