深冷处理对制砖模具芯杆组织与性能的影响

为探究深冷处理对制砖模具芯杆使用寿命的影响, 采用不同的深冷工艺对制砖模具芯杆(65Mn)进行了深冷处理。利用扫描电子显微镜、X射线衍射仪、硬度测试机及摩擦试验机对深冷前后芯杆微观组织结构、硬度与耐磨性进行了观察与测试。结果表明;采用合适的深冷工艺可有效提高芯杆的硬度和耐磨性。其中两次-180 ℃深冷处理2 h、200 ℃回火后效果最为明显, 芯杆残留奥氏体含量降幅达到24.5%, 硬度提高5.7HRC, 摩擦因数下降55.2%。深冷过程中板条状马氏体转变为孪晶马氏体, 且马氏体和托氏体组织会得到进一步细化, 组织中有碳化物析出。

Effects of Deep Cryogenic Treatment on Microstructure and Mechanical Properties of Brick-making Mold Core Rod

In order to explore the effects of deep cryogenic treatment on the service life of brick-making mold core rod, the brickmaking mold core rod (65Mn) was treated by using different cryogenic processes. The microstructure, hardness and wear resistance of the core rod before and after cryogenic treatment were observed and tested with scanning electron microscope, X-ray diffractometer, hardness testing machine and friction test machine. The results show that an appropriate cryogenic process can effectively improve the hardness and abrasion resistance of the core rod. Twice cryogenic treatment at -180 ℃ for 2 hrs followed by tempering at 200 ℃ brings significant effects, that is, retained austenite content and friction factor reduced by 24.5% and 55.2% respectively, and hardness increased by 5.7HRC. In the cryogenic process, the plate-strip-like martensite is transformed to twin martensite, furthermore, the martensite and troostite are further refined, with carbide precipitated.