铝合金半固态坯料二次感应加热的组织演变及控制设想.PDFVIP

2 0 0 9 中国铸造活动周论文集 铝合金半固态坯料二次感应加热 的组织演变及控制设想 尹湘林,杨弋涛,邵玉鹏,张恒华,邵光杰 (上海大学 材料科学与工程学院，上海，200072) 摘要：本文研究了非树枝晶铸造铝合金坯料经过多工位旋转式电磁感应加热过程的组织演变规律， 对实验结果采用了定量金相分析技术和理论模型的分析计算。结果表明，电磁感应加热功率在75kw 的条件下初生 -Al 组织演变过程分为 2 个阶段,首先在感应加热从0s 到303s，共晶组织的熔化， 晶粒以合并长大方式生长，晶粒平均直径持续增大；随后初生 -Al 晶粒的细化和球化基本同步进行， 坯料上、 、下三个部位心部组织平 晶粒直径分别为87.8μm、85.0μm 和84.9μm。 -Al 晶粒以奥 斯特瓦尔德机制生长，通过奥斯特瓦尔德熟化理论计算了长大因子，根据计算结果控制了A356 铝合 金经感应加热后的平 晶粒大小约为66.3μm。 关键词：半固态；二次感应加热；奥斯特瓦尔德熟化；组织演变 Microstructure transition and control approach during induction reheating of billets for semi-solid process of Aluminum alloy YIN Xianglin, YANG Yitao, SHAO Yupeng, ZHANG Henghua, SHAO Guangj ie (School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China) Abstract: This paper researched the law of the microstructure evolution of the non-dendrite aluminum alloy billets heated by the multi-workstation rotating electromagnetic induction, including the quantitative metallographical analysis and theoretical model calculation of the experimental results. The results showed that there were two stages during the microstructure change of the primary -Al phase, under the condition of heating by the electromagnetic induction with 75kw power. The first induction heating ranged from the 0s to the 303s, during which the eutectic structure melted and the grain grew in the way of combining, resulting in the growing of the average diameter of the grain. After that, the primary -Al phase was refined and spheroidized at the same time. The average grain diameters of the billets are 87.8μm on the top, 85μm in the middle and 84.9μm at the bottom. The -Al grain grew according to the Ostwald growth mechanism, and the grain growth exponents were calculated by the Ostwald ripening theory. According to the calculatio