Forming conditions of blisters during solution heat treatment of Al-Si alloy semi-solid die castings

In the present study, numerical simulation method was used to analyze the conditions, resulting in the formation of blisters during solution heat treatment. Blister formation is considered to occur as the height of blister reaches 5 mu m. The effects of process parameters on the magnitude of the forming temperatures of blister (T-b) were discussed. Two kinds of Al-Si alloys were used to analyze the effect of mechanical properties of the alloys on blister forming conditions. Simulation results show that decreasing the initial pressure in gas hole, the long-short axial ratio of gas hole and the size of gas hole, as well as increasing the depth of gas hole and the strength of alloy are helpful to increase the critical temperature of forming blister. These conclusions are helpful for casters to understand the conditions controlling blister formation during solution heat treatment and take actions to avoid the blister defects.