纯铁和高洁净钢的非均质形核

Heterogeneous Nucleation of Pure Iron and High Clean Steel Melts

采用电解纯铁通过高温钼丝炉制备含有不同数量异质核心的试样,用差热分析法分别测定了纯铁和高洁净钢试样在相同冷却速度下的过冷度。结果发现,随着洁净度的提高,高洁净钢和纯铁凝固的过冷度增加,形核功降低,临界晶核半径变小,形核率增大,凝固组织中晶粒的数量增加,晶粒得到细化。在洁净度相同的情况下,高洁净钢形核凝固的过冷度比纯铁小。

By use of electrolytic pure iron, the melts containing different content of heterogeneous nucleus were made in a Mo wire furnace. The DTA method was employed to measure the undercooling degree of liquid pure iron and high clean steel before solidification. The results showed that undercooling degree increased, the nucleation energy decreased, the critical radius of nucleus become smaller, the nucleation ratio and nucleation number increased, and the grain size become finer with the improvement in cleanness of melt. With the same cleanness, the undercooling of high clean steel is smaller than that of pure iron.