2015 Volume 56 Issue 9 Pages 1530-1538
The effects of reheating temperature and time on the microstructure and mechanical properties of thixoforged ZW21 alloy were investigated. The results indicate that the ZW21 alloy is suitable for thixoforming in view of its thixoformability and the resulting mechanical properties. The reheating temperature and duration mainly affect the microstructure, including the size and fraction of primary particles, the microstructure compactness, the solubilities of the solute elements and W phase content, and thus the mechanical properties of the thixoforged alloy. The effects of the reheating temperature are larger than that of the reheating time. These two parameters have an optimum critical value, and values less than or higher than this value decrease the mechanical properties. The appropriate reheating technique is heating for 70 min at 913 K, and the resulting ultimate tensile strength, elongation, and hardness can be up to 238 MPa, 19.4%, and 58 HV, respectively. As the reheating temperature or reheating time increases, the fracture regime has a tendency to change from intergranular mode to transgranular mode and finally to intergranular mode again.
