不同部分重熔温度对半固态过共晶高铬白口铸铁初生相形貌的影响

Effect of Partial Remelting Temperature on Primary Phase in Semisolid Microstructure of Hypereutectic High Cr White Cast Iron

为了考察部分重熔温度对初生碳化物形貌的影响,对过共晶高铬铸铁半固态坯料分别在3个不同温度(1230℃、1250℃、1270℃)进行部分重熔,重熔时间为15min,并借助Leica图像分析仪分别定量描述了初生碳化物形状因子及粒度因子的变化规律。研究表明,半固态组织中初生碳化物形状随着部分重熔温度的升高,呈先改善然后恶化,最后明显改善的趋势变化;碳化物尺寸随着部分重熔温度的升高而逐渐减小。初生碳化物演化过程是由溶质扩散和固、液相界面张力共同作用的结果,然而在较低的部分重熔温度下,固、液相界面张力的作用不明显。在1270℃部分重熔温度下,重熔15min时,可获得理想的部分重熔组织。

In order to investigate the effect of partial remelting temperature on the morphologies of primary carbides, semi-solid billets of Cr17 hypereutectic high chromium cast iron were remelted for 5 min at 1 230℃,1 250℃,1 270℃ respectively, and shape factor and grain factor of primary carbide particles were characterized quantificationally via a Leica image analyzer. The results indicate that firstly with an increase in the partial remelting temperature, the shape of the primary carbides undergoes ameliorating, deteriorating and obvious ameliorating in sequence and the size of primary carbides decreases gradually. Secondly, the process of primary carbides evolution is determined collectively by solute diffusion and phase surface tension, however, the action of surface tension is not evident under the lower remelting temperature condition. Finally, the perfect remelting structure would be obtained at 1 270℃ for 15 min in the investigation.