高铬白口铸铁高温氧化性能的研究

Research on Oxidation-resistant Propertyof High Chromium Iron at High Temperature

由于高铬白口铸铁中铬的碳化物(Fe,Cr)7C3呈孤立的花状、杆状和块状形态存在,从而使韧性、硬度提高,常用作耐磨铸铁。为拓宽应用范围、降低成本和节约贵重的金属镍,将20%Cr、25%Cr的高铬白口铸铁和Cr-Ni钢18-8钢分别在650℃、800℃、和950℃下保温20h、60h、100h后,测定各个试样单位表面积氧化增重量、氧化膜的厚度、基体中铬含量、碳化物中铬含量、试样表面与内部铬含量变化,研究了3种材料的抗氧化性能。结果表明,20%Cr白口铸铁的抗氧化性能在任何温度下都是最差的。650℃、800℃时18-8钢的抗氧化性能与25%Cr白口铸铁相近;950℃时25%Cr白口铸铁的抗氧化性优于18-8钢。因此,25%Cr白口铸铁可以代替18-8钢用作高温耐热材料。

Because carbides of Cr-（Fe,Cr）7C3 show respective pieces, flowers and bars, so the toughness and hardness improve a lot, they often used as friction-resistant iron. In order to make the range of use much larger, reduce cost, save the expensive Ni this experiment studied the oxidation-resistant property of high chromium iron. It was put that the high chromium iron with Cr20%, Cr25% and the 18-8 steel into the heat treatment stove at 650℃, 800℃, 950℃ for 20 h, 60 h,100 h respectively, then determine the increasing weight of oxidation, the thickness of oxidation film of every test sample, also the proportion of Cr in matrix, carbide, superficial and internal of sample is analyzed. Study the oxidation-resistant property of three test sample. The result has indicated that the oxidation-resistant property of high chromium iron with Cr20% is the worst on any situation, the property of 18-8 steel is near that of iron with 25%Cr at 650℃ and 800℃, and the property of iron with 25%Cr is better than that of 18-8 steel at 950%. So the result was got that the iron with 25%Cr can replace 18-8 steel and used as oxidation-resistant material at high temperature.