Effect of Heat Treatment on Structure and Mechanical Properties of Al-30 Wt.% Si Alloys Refined and Modified with Sr+B+RE
On the basis of orthogonal experiment, the effect of heat treatment on structure and mechanical properties of Al-30 wt.% Si alloys refined and modified with Sr+B+RE has been investigated. The results show that the solution temperature and holding time on the alloy microstructure and hardness are affected. When the holding time is constant, as the solution temperature increased, primary silicon more fully integrated into the matrix, the matrix divided by the effect of more and more obvious, eutectic structure becomes coarse, roundness becomes high, the alloy hardness to improve. When the solution temperature is constant, with the holding time increased, primary silicon more fully integrated into the matrix, the matrix divided by the effect of more and more obvious, eutectic structure becomes coarse, roundness becomes high, the alloy hardness increase. When the temperature reaches 540°C, the holding time makes eutectic roundness variation, the hardness declines, the alloy hardness is hardest when solution temperature is 540°C and the holding time is 7h. Optimum heat treatment parameters: 540°C×7h.