Microstructure and mechanical properties of the motorcycle cylinder body of AM60B magnesium alloy formed by combining die casting and forging

Double control forming technology was firstly proposed for meeting the producing requirements of complex Mg alloy parts with high mechanical properties. Not only the high-speed filling but also high-pressure densifying and refining could be achieved in double control forming technology. A typical part of motorcycle cylinder body was used for demonstrating its advantages. The results showed that complete filling could be achieved by injection system of double control forming device and the microstructure of formed part was densified and refined well by its forging system. High mechanical properties such as ultimate tensile strength of 241. MPa and elongation of 13.9% were achieved in the parts formed by double control forming. Compared to die casting, the ultimate tensile strength was increased by 63.9% and elongation was increased by 3.3 times. A large number of fine equiaxed grains with the average size less than 20 μm were found in the microstructure of parts formed by double control forming. A refined microstructure also led to a more uniform distribution of primary equiaxed grains and second phase. Casting defects such as shrinkage voids were removed from the microstructure due to the forging pressure.