16Cr2Mo1Cu高铬铸铁在亚临界处理中硬化行为研究

A study on hardening behavior for high chromium cast iron 16Cr2MolCu under sub-critical treatment

研究了亚临界处理对16Cr2MolCu高铬铸铁的组织转变和性能的影响,并利用X射线衍射分析、磁性法和硬度测定法分析了硬化机制.研究表明:16Cr2MolCu高铬铸铁的铸态组织由残余奥氏体、马氏体和M7C3型共晶碳化物组成,其相对含量分别为77.0%,7.2%和15.8%;在亚临界处理过程中,基体组织中的残余奥氏体析出二次碳化物并在冷却过程中转变为马氏体,使该合金在560-600℃的亚临界处理过程中出现二次硬化;在适当的处理温度和保温时间下,16Cr2MolCu高铬铸铁可得到最高的硬度.

The effect of sub-critical treatment on microstructure and properties of 16Cr2MolCu high chromium cast iron is studied in this paper. The hardening mechanism is analyzed by using X-ray diffraction, magnetism method and hardness test. The results show that the microstructure of the as-cast high chromium cast iron consists of retained austenite(77. 0% ) , martensite (7. 2% ) and M7C3 typeeutectic carbide(15. 8% ). The retained austenite in the matrix can precipitate secondary carbide in the process of sub-critical treatment, and transforms into martensite in cooling process. This causes the secondary hardening of the alloy under sub-critical treating at 560-600 ℃ for 6-20 h. The high chromium cast iron can obtain the highest hardness under the proper heat-treatment temperature and time.