中文摘要：

采用硬度计和光学显微镜对试样进行硬度测试和金相组织分析，研究了二次枝晶臂间距对A357合金时效动力学的影响。研究发现，在相同的条件下，随着A357合金试样二次枝晶臂间距的增大，固溶处理后达到的硬度值减小，而合金试样的时效硬度峰值推迟出现；通过对时效处理实验结果进行回归分析和量纲分析，得到时效硬度的数学模型，并验证了该模型的有效性。

英文摘要：

Through the hardness measurement with hardometer and the metallographic analysis with optical microscope, the influences of second dendrite arm spacing （SDAS） on aging kinetics of A357 alloy are studied. The results show that under the same conditions, with the rise of SDAS, the hardness after solid solution treatment reduces, and the ageing hardness peak appears later. By means of regression analysis and dimensional analysis on the results of aging tests, a mathematical model for aging hardness is obtained with its validity verified.