高铬铸铁成分优化与高温性能研究
发布时间：2019-01-02 10:42
【摘要】：高铬铸铁是一种铬系耐热耐磨铸铁,具有较好的高温耐磨性能,在工业生产的许多领域广泛使用。为了控制生产成本和实现安全稳定生产,企业对高铬铸铁高温环境下的使用性能要求不断提高。因此,开发新的高铬铸铁,使其具有更好的高温耐磨性能,是材料研究领域的重要工作。本论文是在对现有常用高铬铸铁的成分、组织和性能以及氮、钼元素可能产生的作用效果进行分析的基础上,熔炼合成含有氮、钼元素的高铬铸铁,使用自制的高温磨损试验装置以及材料组织观测和强度测试装置对合金的高温性能进行了分析。首先,以碳、铬、钼和氮作为变化因素,以高温(900℃)下合金磨损量、氧化增重、抗拉强度作为性能指标,通过正交试验进行合金成分优化。其后,以正交试验所得合金最优成分为基础,改变合金中的钼和氮含量进行单变量实验,分析讨论氮、钼元素对高铬铸铁高温性能的影响以及性能变化的组织原因。由分析正交试验结果可知,利用综合评分法得出合金的最优组分为2.6wt%碳、28wt%铬、3wt%钼、0.2wt%氮。在此化学组成下,合金的高温单位磨损量为28.5g/m2·h、高温单位氧化增重量为0.023 g/m2·h,均为最小,高温抗拉强度最大达到182.61 MPa,同时室温硬度最高为48.2 HRC。C、Cr两元素对所有高温性能均为最显著影响因素,而Mo、N对高温性能指标的影响程度次序有所不同。对合金的组织观察分析表明,氮元素主要以固溶和在基体金属中的固溶及碳氮化物等形式存在,并引起碳化物由长条状向条块状的转变以及尺寸变小。在氮含量为0.2wt%时碳化物所占比例最大为26.84%,碳化物尺寸为69.32μm2最小。钼元素主要形成钼的碳化物Mo2C,分布在共晶碳化物之中。随着含钼量的增加,长条状碳化物减少,块状及球状碳化物增多,碳化物长宽比减小而且棱角变得更加圆滑,而且更趋向于离散分布。从合金组织与性能的关系来看,氮元素固溶所引起的基体硬度提高、碳化物数量增加以及形成碳氮化物是提高合金耐磨性的主要原因,碳化物形貌优化和尺寸细化有利于提高高温强度,但氮的析出便于氧向内部扩散且弱化了氧化膜与基体结合,对合金的高温氧化性能是不利的。合金中加入钼后形成的高硬Mo2C质点,是钼提高合金耐磨性的重要原因;钼细化合金晶粒,使碳化物形貌优化和离散分布,有利于提高高温下合金的抗拉强度;碳化钼的形成降低了基体的碳含量,可以在一定程度上改善合金的抗氧化性能。
[Abstract]:High chromium cast iron is a kind of chromium series heat resistant and wear resistant cast iron, which has good high temperature wear resistance and is widely used in many fields of industrial production. In order to control production cost and realize safe and stable production, the performance requirements of high chromium cast iron under high temperature environment are improved. Therefore, it is an important work in the field of material research to develop new high chromium cast iron and make it have better wear resistance at high temperature. Based on the analysis of the composition, microstructure and properties of the existing high chromium cast iron, and the possible effect of nitrogen and molybdenum elements, the high chromium cast iron containing nitrogen and molybdenum was synthesized by smelting. The high temperature properties of the alloy were analyzed by using the self-made high temperature wear test device and the material microstructure observation and strength test device. Firstly, carbon, chromium, molybdenum and nitrogen were taken as the variable factors, and the alloy wear, oxidation weight and tensile strength at high temperature (900 鈩，
本文编号：2398391
[Abstract]:High chromium cast iron is a kind of chromium series heat resistant and wear resistant cast iron, which has good high temperature wear resistance and is widely used in many fields of industrial production. In order to control production cost and realize safe and stable production, the performance requirements of high chromium cast iron under high temperature environment are improved. Therefore, it is an important work in the field of material research to develop new high chromium cast iron and make it have better wear resistance at high temperature. Based on the analysis of the composition, microstructure and properties of the existing high chromium cast iron, and the possible effect of nitrogen and molybdenum elements, the high chromium cast iron containing nitrogen and molybdenum was synthesized by smelting. The high temperature properties of the alloy were analyzed by using the self-made high temperature wear test device and the material microstructure observation and strength test device. Firstly, carbon, chromium, molybdenum and nitrogen were taken as the variable factors, and the alloy wear, oxidation weight and tensile strength at high temperature (900 鈩，
本文编号：2398391
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