稀土和硅对高铬耐热铸铁影响的研究
发布时间：2018-08-04 09:35
【摘要】：目前，常用的耐热材料主要有耐热钢和耐热铸铁。耐热钢的耐热性较好，力学性能较高，但成本较高。耐热铸铁具有一定的力学性能，成本相对较低，但耐热性不如耐热钢。本文以铬含量为20%的高铬铸铁为研究对象，采用加入稀土、硅的方法，研究对高铬耐热铸铁的影响。通过光学显微镜，研究稀土、硅对高铬白口铸铁组织的影响。对不同成分的高铬铸铁进行高温氧化实验，计算其氧化速率，分析氧化膜的组成。并对不同成分的试样进行耐磨性、热疲劳、硬度测试。研究结果表明： 稀土含量由0增加到0.60%，高铬铸铁奥氏体由树枝晶向柱状晶和等轴晶转变，碳化物由连续的网状趋于块状和条状发展；高铬铸铁氧化速率从5.566mg·cm-2·h-1降到3.276mg·cm-2·h-1；磨损量由0.1521g降为0.1485g；高铬铸铁铸态硬度从45.2HRC增加到49.9HRC；将添加稀土的高铬耐热铸铁，在1100℃下进行热疲劳实验，试样进行40次反复加热、冷却，均未出现裂纹。 硅含量低于2.5%时，高铬铸铁奥氏体枝晶较多，共晶碳化物的连续程度较高，以网状或条状存在。硅含量大于2.5%时，奥氏体枝晶减少，共晶碳化物显著的细化，以细小的块状和粒状形式存在，分布均匀；随着硅含量的增加，氧化速率先下降后上升，硅含量在2.0%时，最低为2.825mg·cm-2·h-1；随着含硅量的增加，磨损量呈降低趋势，，最小值为0.1468g；硅含量从1.5%增加到3.5%，高铬铸铁铸态硬度从49.3HRC增加到52.5HRC；将添加硅的高铬耐热铸铁，在1100℃下进行热疲劳实验，试样进行40次反复加热、冷却，均未出现裂纹。
[Abstract]:At present, the commonly used heat-resistant materials are mainly heat-resistant steel and heat-resistant cast iron. Heat-resistant steel has better heat resistance, higher mechanical properties and higher cost. Heat-resistant cast iron has some mechanical properties and low cost, but its heat resistance is inferior to heat-resistant steel. In this paper, the effect of adding rare earth and silicon on high chromium cast iron with 20% chromium content was studied. The effect of rare earth and silicon on the microstructure of high chromium white cast iron was studied by optical microscope. High chromium cast iron with different composition was oxidized at high temperature, the oxidation rate was calculated and the composition of oxide film was analyzed. The wear resistance, thermal fatigue and hardness of the samples with different compositions were tested. The results showed that the austenite of high chromium cast iron changed from dendrite to columnar crystal and equiaxed crystal, the carbides changed from continuous mesh to block and strip, the oxidation rate of high chromium cast iron decreased from 5.566mg cm-2 h-1 to 3.276mg cm-2 h-1, the content of rare earth increased from 0 to 0.60, and the austenite of high chromium cast iron changed from dendrite to columnar and equiaxed crystal. The wear rate was reduced from 0.1521g to 0.1485g.The as-cast hardness of high-chromium cast iron was increased from 45.2HRC to 49.9HRC.The thermal fatigue test of heat-resistant cast iron with rare earth addition was carried out at 1100 鈩
本文编号：2163426
[Abstract]:At present, the commonly used heat-resistant materials are mainly heat-resistant steel and heat-resistant cast iron. Heat-resistant steel has better heat resistance, higher mechanical properties and higher cost. Heat-resistant cast iron has some mechanical properties and low cost, but its heat resistance is inferior to heat-resistant steel. In this paper, the effect of adding rare earth and silicon on high chromium cast iron with 20% chromium content was studied. The effect of rare earth and silicon on the microstructure of high chromium white cast iron was studied by optical microscope. High chromium cast iron with different composition was oxidized at high temperature, the oxidation rate was calculated and the composition of oxide film was analyzed. The wear resistance, thermal fatigue and hardness of the samples with different compositions were tested. The results showed that the austenite of high chromium cast iron changed from dendrite to columnar crystal and equiaxed crystal, the carbides changed from continuous mesh to block and strip, the oxidation rate of high chromium cast iron decreased from 5.566mg cm-2 h-1 to 3.276mg cm-2 h-1, the content of rare earth increased from 0 to 0.60, and the austenite of high chromium cast iron changed from dendrite to columnar and equiaxed crystal. The wear rate was reduced from 0.1521g to 0.1485g.The as-cast hardness of high-chromium cast iron was increased from 45.2HRC to 49.9HRC.The thermal fatigue test of heat-resistant cast iron with rare earth addition was carried out at 1100 鈩
本文编号：2163426
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