Heat transfer and grain refining mechanism during melt treatment by cooling sloping plate  

作　　者：Renguo GUAN Zhanyong ZHAO Runze CHAO Hongqian HUANG Chunming LIU 

机构地区：[1]College of Materials and Metallurgy,Northeastern University,Shenyang 110819,China

出　　处：《Acta Metallurgica Sinica(English Letters)》2012年第4期320-328,共9页金属学报（英文版）

基　　金：financially supported by the National Natural Science Foundation of China (Nos. 51034002 and 50974038);the Fok Ying Tong Education Foundation (No. 132002);National Basic Research Program of China (973 program)(No.2011CB610405)

摘　　要：Heat transfer of flow melt and grain refining mechanism during melt treatment by the cooling sloping plate were investigated. The results show that the cooling sloping plate can refine not only grains of alloys but also can obviously refine pure metal. Cooling ability of the plate is the key factor that induces grain refining, the plate material and the flow amount can affect cooling rate of the melt and thus affect refining effectiveness. The cooling rate of the melt on the cooling sloping plate is much faster than that of the conventional casting process, which can reach 1000 K/s and belongs to meta-rapid solidification scope. The thickness of the temperature boundary layer is much larger than that of the velocity boundary layer on the sloping plate, but the temperature gradient is small in the temperature boundary layer. Under strong cooling action by the cooling plate, most parts of the melt on the plate surface can form undercooling, which causes continuous eruptive nucleation, this is the main grain refining mechanism, and the heterogeneous nucleation on the plate surface is a helpful supplement for the nucleation.Heat transfer of flow melt and grain refining mechanism during melt treatment by the cooling sloping plate were investigated. The results show that the cooling sloping plate can refine not only grains of alloys but also can obviously refine pure metal. Cooling ability of the plate is the key factor that induces grain refining, the plate material and the flow amount can affect cooling rate of the melt and thus affect refining effectiveness. The cooling rate of the melt on the cooling sloping plate is much faster than that of the conventional casting process, which can reach 1000 K/s and belongs to meta-rapid solidification scope. The thickness of the temperature boundary layer is much larger than that of the velocity boundary layer on the sloping plate, but the temperature gradient is small in the temperature boundary layer. Under strong cooling action by the cooling plate, most parts of the melt on the plate surface can form undercooling, which causes continuous eruptive nucleation, this is the main grain refining mechanism, and the heterogeneous nucleation on the plate surface is a helpful supplement for the nucleation.

关 键 词：Grain refining NUCLEATION Cooling rate Sloping plate Temper-ature boundary layer 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG292[金属学及工艺—金属材料]