半固态高铬铸铁的流变铸造组织的演变

Evolution of Rheocast Structure of High Chromium White Iron

摘要:

通过研究搅拌强度，冷却速度对高铬铸铁流变铸造组织的影响及采用EMPA和EBSD技术研究小角晶界，晶粒簇丛的精细特征，发现冷却速度控制了枝晶臂所受扭矩大小与根部直径大小的比例，适当的冷却速度可促进形成头部大，根部小的枝晶臂的形成，从而加速枝晶臂的折断。聚集的小角晶界是扭折但未完全折断的细小枝晶臂在经熟化过程后形成的主干与枝晶臂的界面，晶粒簇丛是由许多被扭折的枝晶臂演变而成。

Abstract:

The effect of stirring strength and t he cooling rate on the rheocast structure of a high chromium white iron were studied.The characteristics of the special low a ngle subgrain boundaries and agglom eration of subgrains were analyzed b y EPMA and EBSD technique.It was found that the cooling rate decid es the ratio of the stress on the dendr ite arm to the diameter of the dendrite root.A proper cooling rate favers the formation of dendrite arm s with big head and thin root and accelerates the breaking of the dendrite a rms.The clustered special subgrain boudaries are the boundaries between the stem and ripened dendr ite arms.The agglomerations of the s ubgrains were indeed evolved from the bent dendrite arms with big h ead and thin root.