Lv Haiyang, Zhou Rongfeng, Li Lu, Ni Haitao, Zhu Jiang, Feng Tong
College of Materials and Chemical Engineering, Chongqing University of Arts and Sciences, Chongqing 402160, China.
College of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China.
Materials (Basel). 2018 Nov 8;11(11):2220. doi: 10.3390/ma11112220.
The effect of electric current pulse on the microstructure and corrosion resistance of hypereutectic high chromium cast iron was explored. The morphology of carbides in solidification microstructure was observed by an optical microscope and a scanning electron microscope and the composition was determined by an electron probe micro-analyzer. The microhardness of primary carbides and corrosion resistance of samples were also compared. Under the active of electric current pulse, the microstructure of hypereutectic high chromium cast iron was homogenized and its performance improved accordingly. On treatment by electric current, the morphology of primary carbides changed from thick long rods to hexagonal blocks or granular structures. The interlayer spacing of eutectic carbide decreased from ~26.3 μm to ~17.8 μm. Size statistics showed that the average diameter of primary carbide decreased from ~220 μm to ~60 μm. As a result, microhardness increased from 1412 HV to 1511 HV. No obvious microcrack propagation was found at the microindentation sites. The average length of microcracks decreased from ~20.7 μm to ~5.7 μm. Furthermore, corrosion resistance was remarkably enhanced. The average corrosion rate decreased from 2.65 mg/cm²·h to 1.74 mg/cm²·h after pulse current treatment.
研究了电流脉冲对过共晶高铬铸铁组织和耐蚀性的影响。通过光学显微镜和扫描电子显微镜观察凝固组织中碳化物的形态，并用电子探针微分析仪测定其成分。还比较了初生碳化物的显微硬度和样品的耐蚀性。在电流脉冲作用下，过共晶高铬铸铁的组织均匀化，性能相应提高。经电流处理后，初生碳化物的形态由粗长杆状变为六方块状或粒状结构。共晶碳化物的层间距从26.3μm减小到17.8μm。尺寸统计表明，初生碳化物的平均直径从220μm减小到60μm。结果，显微硬度从1412 HV提高到1511 HV。在微压痕部位未发现明显的微裂纹扩展。微裂纹的平均长度从20.7μm减小到5.7μm。此外，耐蚀性显著增强。脉冲电流处理后，平均腐蚀速率从2.65mg/cm²·h降至1.74mg/cm²·h。
