为了提高性能且降低成本，设计末端激冷的砂型铸造实验，研究A356铝合金的凝固组织随冷却速率的演化特征以及不同凝固组织对后续固溶处理过程的影响。实验结果表明：初生相α(Al)的二次枝晶间距、共晶 Si的尺寸以及Al?Si共晶体积分数随冷却速率的提高而减小。经过540°C固溶处理1 h后淬火，当冷却速率为2.6 K/s时，共晶Si完全球化；当冷却速率为0.22 K/s时，共晶Si发生部分球化；当冷却速率为0.22和0.12 K/s时，仅共晶Si的边缘发生钝化。同时，当冷却速率为2.6 K/s时，合金具有最大的显微硬度。由此可见，经过高冷却速率凝固后，细化的共晶Si更容易发生球化，从而在给定固溶温度条件下，降低了固溶处理所需要的时间，即降低了生产成本。
For the compromise of mechanical properties and product cost, the end-chilled sand casting technique was applied to studying the microstructure evolution of A356 Al alloy with cooling rate and the effect of different as-cast microstructures on the subsequent solution-treatment process. The experimental results show that the secondary dendrite arm spacing (SDAS) of primaryα(Al), the size of eutectic Si and the volume fraction of Al?Si eutectic are reduced with increasing the cooling rate. Eutectic Si, subjected to solution treatment at 540 °C for 1 h followed by water quenching to room temperature, is completely spheroidized at cooling rate of 2.6 K/s; is partially spheroidized atcooling rate of 0.6 K/s; and is only edge-rounded at cooling rates of 0.22 and 0.12 K /s. Whilst the microhardness is also the maximum at cooling rate of 2.6 K/s. It consequently suggests that subjected to modification by high cooling rate, the eutectic Si is more readily modified, thus shortening the necessary solution time at given solution temperature, i.e., reducing the product cost.
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