液相线上脉冲电流作用时间对过共晶高铬铸铁凝固组织的影响

Effect of electric current pulse treatment time above liquidus line on solidification microstructure of hypereutectic high chromium cast iron

在过共晶高铬铸铁熔体从1355℃冷却到液相线过程中施加脉冲电流,研究脉冲电流处理时间对其凝固组织的影响,利用光学显微镜、X射线衍射等技术手段对脉冲处理后铸铁组织中的初生碳化物的尺寸、形态、种类和演变过程进行分析。结果表明：在液相线以上施加脉冲电流可改善初生碳化物在基体中的分布状态,并使组织细化;脉冲电流作用时间与细化效果呈一定相关关系,随着作用时间增加,初生碳化物平均直径、共晶碳化物片层厚度和间距先减小后增大;作用时间为3.0 min时可以获得尺寸细小、形貌均一的初生碳化物。

Electric current pulse（ ECP） was applied to hypereutectic high chromium cast iron（ HHCCI） melt during cooling from 1355 ℃to liquidus line,and the effect of electric current pulse treatment time on solidification microstructure of the HHCCI was studied. The size,morphology,types and evolution of the primary carbides during solidification in the HHCCI after ECP treatment were analyzed by means of optical microscope and X-ray diffraction. The results show that the distribution of primary carbides in the matrix can be improved by applying ECP above the liquidus line,and the microstructure can be refined. The ECP treatment time is related to the refining effect,and with the increase of the treatment time,the average diameter of the primary carbides,slice spacing and layer thickness of eutectic carbides lamellar decrease firstly and then increase. The primary carbides with fine size and uniform morphology can be obtained when the ECP treatment time is 3. 0 min.