碳、铬含量及热处理工艺对高铬铸铁力学性能的影响

Effects of carbon and chromium content and heat treatment on mechanical properties of high chromium cast iron

为了提高高铬铸铁材料的服役寿命,用4因素、3水平正交试验方法研究了碳、铬含量、淬火温度和回火温度对高铬铸铁力学性能的影响,确定获得最佳性能的稳定工艺。结果表明、当高铬铸铁的碳、铬的含量(质量分数)分别为2.7%和18%时,进行1040℃淬火+280℃回火的试样综合力学性能最高,其洛氏硬度为62 HRC,冲击韧度为8.2 J/cm^2。从显微组织可以看出,综合力学性能最好的高铬铸铁试样晶粒细小,碳化物的析出量减少,并且出现了球状碳化物。由XRD分析显示,综合力学性能最低的高铬铸铁试样中奥氏体含量高于综合力学性能最高的试样。此外,EDS能谱分析显示析出的碳化物主要为M_7C_3型碳化物。

To improve the service life of high chromium cast iron, the effects of carbon and chromium content, quenching and tempering temperature on the mechanical properties were investigated by using the orthogonal test method with four factors and three levels, and the stable process with the best performance was obtained. The results show that when the carbon and chromium content of high-chromium cast iron samples （mass fraction） are 2.7% and 18%, respectively, and when quenched at 1040 ℃ and tempered at 280 ℃, the Rockwell hardness and the impact toughness of the cast iron can reach 62 HRC and 8.2 J/cm2 , respectively, which shows the best comprehensive mechanical properties. The microstructure observation results indicate that the high-chromium cast iron samples with the best mechanical properties has small grains, reduced amount of precipitation of carbide, and spherical carbide. The XRD analysis results show that the high- chromium cast iron sample with the lowest mechanical properties contains more retained austenite than that of samples with the highest mechanical properties. In addition, the EDS spectrum analysis results show that the precipitated carbide is mainly M7 C3 type.