含碳量对Mn8Cr2Si钢显微组织及性能的影响

Effects of Carbon Content on Microstructure and Properties of Mn8Cr2Si Steel

研究了含碳量对Mn8Cr2Si钢显微组织、力学性能、耐磨性能和耐腐蚀性能的影响。利用光学显微镜(OM)对奥氏体晶粒的尺寸变化进行观察,并利用扫描电子显微镜(SEM)分析冲击断口及磨损形貌。结果表明,随含碳量的增加,奥氏体晶粒逐渐细化,但当含碳质量分数超过0.8%时,晶粒开始粗化。由于奥氏体晶粒细化,其晶界总面积增大,应力集中降低,抑制了裂纹的形成与扩展。因此,奥氏体晶粒越细小,其力学性能越好,而力学性能的提升有助于提高其耐磨性能。分析发现,奥氏体晶粒尺寸同样影响Mn8Cr2Si钢的耐腐蚀性能,细化后的奥氏体晶粒能提高其耐腐蚀性能。当Mn8Cr2Si钢含碳质量分数为0.8%时,晶粒尺寸可细化到143μm,综合力学性能和耐腐蚀性能优异。

The effects of carbon content on the microstructure, mechanical property, wear resistance and corrosion resistance of Mn8Cr2Si steel was investigated. The change of austenite grain size was observed by optical microscope （OM）. The impact fracture and wear morphologies were analyzed by scanning electron microscopy （SEM）. The results indicate that the austenite grain becomes refinement with the increase of carbon content. Nevertheless, when the carbon content is over 0.8%, the grain starts to be coarse. Due to the refinement of the austenite grain, the total area of grain boundaries increases and the stress concentration is reduced, which suppress the formation and propagation of cracks. Therefore, the finer the austenite grains, the better the mechanical property is, and the upgrade of mechanical property will help to improve the wear resistance of Mn8Cr2Si steel. It is found that the austenite grain size also affects the corrosion resistance of Mn8Cr2Si steel, and the corrosion resistance can be improved with the refinement of austenite grains. When the carbon content of Mn8Cr2Si steel is 0.8%, the grain size can be refined to be 143μm, and the composite mechanical property and the corrosion resistance are excellent.