摘要
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, the secondary hardening structure and precipitation hardening mechanism of high wear resistant cold forming die steel Cr8Mo2WV3Si have been investigated. The results of TEM analysis show that the special carbide of Cr8Mo2WV3Si steel precipitated during tempering is mainly MC type carbide. The orientation between MC type carbide and matrix is found to be fulfilled the Baker-Nutting's relation: (010)_(MC)//(010)_α, [001]_(MC)//[101)_α The nucleation mechanism of MC-type carbide is dislocation nucleation mechanism and homogeneous nucleation mechanism. The results of secondary hardening structure hardness determination, compressive strength testing and the formation, distribution, size of MC-type carbide determination show that secondary hardening of Cr8Mo2WV3Si are mainly caused by precipitation of MC type carbide. The precipitation hardening mechanism is Orowan mechanism. Furthermore, slide wear testing, impact wear testing and mechanical property testing have been carried out. The wear surface has also been observed
by means of SEM. The results show that the wear resistance of Cr8Mo2WV3Si is mainly related to secondary hardening structure, not hardness, in eitherslide friction condition or impact friction condition. The requirements of wear resistance on size, distribution and volume fraction of precipitation phase in
slide friction condition is different from that in impact friction condition.
