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本文对耐磨冷变形工模具钢Cr8Mo2WV3Si的二次硬化组织及其沉淀强化机制作了较详细的研究,透射电镜(TEM)分析表明,该钢在回火过程中析出的特殊碳化物主要是MC型碳化物。它与基体间满足Baket-Nutting关系: (010)_(MC)//(010)_α,[001]_(MC)//[101]_α MC质点的形核有位错上形核和均匀形核两种机制。通过二次硬化组织硬度测定和压缩试验以及MC型碳化物形态、分布、尺寸的测定,证明该钢产生二次硬化主要是MC碳化物的沉淀强化引起的。沉淀强化机制为Orowan绕越机制。本文在此基础上,进一步进行了滑动摩擦条件下和冲击摩擦条件下的磨损试验以及力学性能试验,并对磨损表面进行了扫描电镜观察。实验结果表明:无论在滑动摩擦条件下还是在冲击摩擦条件下,该钢的耐磨性主要和二次硬化组织有关,而和硬度没有直接关系。所不同的是,在滑动摩擦条件下和在冲击摩擦条件下该钢的耐磨性对沉淀相的大小,分布和体积分数的要求各不相同。
In this paper, we made a more detailed study on the secondary hardening structure of Cr8Mo2WV3Si wear-resistant and cold-working tool steel and its precipitation hardening mechanism. Transmission electron microscopy (TEM) analysis showed that the special carbide precipitated during tempering was mainly MC Carbide. It satisfies the Baket-Nutting relation with the matrix: (010) _ (MC) // (010) _α, [001] _ (MC) // [101] _α The nucleation of MC particles has dislocation nucleation and uniform Nucleation two mechanisms. Through secondary hardness test and compression test and MC type carbides shape, distribution and size determination, it is proved that the secondary hardening of the steel is mainly caused by precipitation hardening of MC carbides. Precipitation enhancement mechanism for the Orowan bypass mechanism. Based on this, the wear test and the mechanical property test under the conditions of sliding friction and impact friction were further carried out. The wear surface was observed by scanning electron microscopy. The experimental results show that the wear resistance of the steel is mainly related to the secondary hardening structure, but not directly related to the hardness, both in the sliding friction condition and the impact friction condition. The difference is that the wear resistance of the steel under sliding friction conditions and under impact friction conditions varies in size, distribution and volume fraction of the precipitated phase.