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采用过流冷却体法制备高铬铸铁半固态浆料,对初生相的细化过程进行研究。结果表明:过流冷却体改变了高铬铸铁熔体的温度场、成分场,且合金熔体间、熔体与过流冷却体间存在剪切应力,使初生相得到细化;树枝状奥氏体和长杆状M7C3碳化物的细化受熔体的温度、温度梯度和粘度影响较大;在凹槽半径较小或温度较高的过流冷却体中熔体温度较高,温度梯度较小,粘度较小,使奥氏体的细化以枝晶臂熔断为主;M7C3碳化物因[0001]方向生长速度较小及剪切作用而细化;在凹槽半径较大或温度较低的过流冷却体中温度较小,温度梯度较大,粘度较大,剪切应力较大,使奥氏体的细化以枝晶臂弯曲折断为主,碳化物以折断、分裂而细化。
High-chrome cast iron semi-solid slurry was prepared by over-current cooling method and the refining process of primary phase was studied. The results show that the overcurrent cooling body changes the temperature field and the composition field of the high chromium cast iron melt, and the shear stress exists between the alloy melt, the melt and the overcurrent cooling body to refine the primary phase. The dendritic The refinement of martensite and long rod M7C3 carbides is greatly influenced by the temperature, temperature gradient and viscosity of the melt. In the case of overcooled cooling body with small groove radius or high temperature, the melt temperature is higher and the temperature gradient Smaller, less viscous, the austenite refinement to the dendritic arm blown mainly; M7C3 carbide growth due to the direction of [0001] smaller and shear thinning; in the groove radius larger or temperature Lower overcurrent cooler body temperature is smaller, the temperature gradient larger, larger viscosity, shear stress is larger, the austenite refinement to dendritic arm bending fracture, carbides to break, split and Refine.