【作者】 张丙静；

【导师】 石巨岩； 田晓青；

【作者基本信息】 太原理工大学 ， 材料学， 2007， 硕士

【摘要】 伴随着社会的发展、进步，机械设备日趋小型化和高性能化，这就强烈地要求机械零件具有更高的力学性能和良好的可靠性。普通渗碳钢常规渗碳处理时，渗碳层表面的含碳量约为0.8～1.0％，金相组织为在马氏体和残余奥氏体所构成的基体上分布着碳化物。碳化物的存在及其数量、大小、分布和形态对于零件表面的硬度、强度及耐磨性起着至关重要的作用。为进一步提高其力学性能，欲增加碳化物的数量而采用在较高碳势条件下渗碳时，往往会沿奥氏体晶界析出网状碳化物，而碳化物形态的恶化将导致其力学性能显著下降。本文从渗碳工艺和渗碳用钢两方面入手，针对常规低合金渗碳钢20Cr研发了超饱和渗碳工艺；利用经验分子电子理论设计了超饱和渗碳钢35Cr3SiMnMoV；利用剥层化学分析法测的渗碳层具有高达2％的含碳量；利用XJL-02A立式金相显微镜观察可知：金相组织为在马氏体和残余奥氏体所构成的基体上弥散分布着大量细小的合金碳化物颗粒；通过X射线衍射确定其碳化物为：Cr₇C₃、Mo₂C、VC等碳化物，并对其弥散碳化物的形成机理进行了初步探讨。力学实验结果表明：超饱和渗碳钢35Cr3SiMnMoV，具有R_el=1630Mpa的高强度和Akv=72J（平均值）的高韧性；35Cr3SiMnMoV经渗碳淬火+低温回火以后，渗碳层硬度比常规渗碳层硬度提高了20％以上，达到HV0.01912-HV0.011025；在相同磨损条件下，超饱和渗碳层的耐磨性比常规渗碳层提高了90％以上，大幅提高了零件的力学性能。在满足技术指标的前提下有利于实现机械设备小型化和高性能化；若零件的几何尺寸相同，则由本文研发的超饱和渗碳工艺和超饱和渗碳钢所生产的零件具有更长的使用寿命。更多还原

【Abstract】 With the development of the society,the mechanicalequipment became smaller and with more functions. So it is necessary for the machine part to be credible and with excellent mechanical properties. The surface of the normal cementation steel contains 0.8-1.0% carbon after the heat treatments, carbide distributes on the martensite and austenite. The amount, distribution, size and form have something important to the hardness, strength and abrasion resistance of the surface. In order to enhance the mechanical properties, the amount of the carbon should be increased with carburization, but the netted carbide would precipitate from the grain boundary of the austenite, and it is detrimental for the mechanical properties.In this dissertation, from the carburization process and cementation steel, the super carburization process especial designed for the alloy cementation steel is developed. The super saturation cementation steel 35Cr3SiMnMoV is designed according to the molectronic. The amount of the carbon in the carburization layers is 2% according to the chemical analysis. From the metallographic microscope, it can be known that there are some small alloy carbide distributes on the matrix mainly composed martensite and austenite. The carbide consist Cr₇C₃、Mo₂C、VC, and the forming mechanism is discussed in the paper. The hardness of the carburization layers increase by 20 percent, up to HV_0.01912-HV_0.011025. At the same abrasion condition, the abrasion resistance increase by 90 percent. The mechanical properties of the machine part enhance a lot. And it is beneficial for the mechanical equipment to be miniature with higher capability. If the machine parts have the same size, through the super carburization process, the machine part would be used for a longer time.更多还原