铝合金半固态坯料感应加热过程的组织演变及控制  

Microstructural Evolution and Control of Semi-solid Aluminum Alloy during Electromagnetic Induction Reheating

作　　者：尹湘林[1] 杨弋涛[1] 邵玉鹏[1] 张恒华[1] 邵光杰[1] 

机构地区：[1]上海大学材料科学与工程学院

出　　处：《特种铸造及有色合金》2009年第8期717-720,共4页Special Casting & Nonferrous Alloys

摘　　要：研究了非树枝晶A357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,对试验结果进行了定量金相分析,并借助理论模型探讨了晶粒演变机制。结果表明,电磁感应加热功率在75kW的条件下,初生α-Al组织演变过程分为2个阶段,首先在感应加热从0到303s,共晶组织熔化,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α-Al晶粒的细化和球化基本同步进行,坯料上、中、下3个部位心部组织平均晶粒直径分别为87.8、85.0、84.9μm;形状系数分别为0.73、0.69和0.71。α-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出长大因子在2.20～2.70之间。根据计算结果,A356经感应加热后的平均晶粒大小为66.3μm。Microstructural evolution of the non-dendrite A357 aluminum alloy billets heated by the multi-workstation rotating electromagnetic induction was analyzed including quantitative metallographic observation and theoretical model calculation. The results reveal that there exist two stages in the microsrtuctural evolution of the primary α-Al phase in the alloy billets during electromagnetic induction heating with 75kW. The first stage,with heating time from 0 to 303 seconds,eutectic structure is melted and grain is grown by emerging,meanwhile,the average diameter of grain is increased;the second stage,the primary α-Al phase is refined accompanying with spheroidization. The average grain diameters in the billets are 87.8 μm on the top,85μm in the middle and 84.9 μm at the bottom with shaping factors of 1.37,1.44 and 1.40,respectively. Growth of α-Al phase is characterized by the Ostwald growth mechanism. Based on the Ostwald ripening theory,the growth exponent of 2.2~2.7 can be calculated. According to the calculated result,the average grain diameter in A356 aluminum alloy billets can be controlled to 66.3μm after electromagnetic induction heating.

关 键 词：半固态 电磁感应加热 奥斯特瓦尔德熟化 组织演变 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG249.9[金属学及工艺—金属材料]