【作者】 王均；

【导师】 沈保罗；

【作者基本信息】 四川大学 ， 材料学， 2003， 硕士

【摘要】 高铬耐磨铸铁（high chromium cast iron，abbr．HCCI）的显微组织是在高强度又有良好韧性的基体上分布着高硬度的且彼此孤立分布而连不成网状的M₇C₃型共晶碳化物。正是由于它的特殊的显微组织使得它具有杰出的耐磨能力，而被广泛地应用于矿山、冶金、建材、电力和化工等行业。铸态高铬耐磨铸铁并不具有很好的耐磨能力，一般都要经过适当的热处理才能具有很好的使用性能。亚临界处理是一种很好的高铬耐磨铸铁热处理方法，高铬耐磨铸铁经过亚临界处理后能获得较好的使用性能。随着工业技术的发展，人们常常在高铬耐磨铸铁中添加一些合金元素来提高它的使用性能。为了合理而高效地利用合金元素，研究合金元素对高铬耐磨铸铁凝固组织和亚临界处理的影响，是很有必要的。本文正是通过一系列的对比实验和深冷处理来研究锰、铜和钒对高铬耐磨铸铁性能的影响， 本文通过电子探针、X衍射、SEM、DTA、磁性法和硬度测量法来研究了一系列不同的成分的高铬耐磨铸铁的凝固组织和亚临界处理的时效硬化行为，详细分析了锰、铜和钒三种合金元素对高铬耐磨铸铁性能的影响，还分析了深冷处理对高铬耐磨铸铁亚临界硬化行为的影响。 研究结果表明：高铬耐磨铸铁的铸态组织由奥氏体，马氏体和M₇C₃型碳化物组成。在高铬耐磨铸铁中分别加入Mn、Cu、V，基于不同的原因高铬耐磨铸铁的铸态试样的残余奥氏体含量都增加；Cu能显著增大碳化物的数量；V能细化晶粒，改善组织结构和分布，提高材料的硬度。高铬耐磨铸铁在一定的亚 四川大学硕卜学位论文临界处理过程中会发生二次硬化效应，并且其显微组织中残余奥氏体含量越高，二次硬化效果越明显。二次硬化的具体机制是由于在亚临界处理过程中，由于残余奥氏体中的合金碳化物的析出使得Ms点上升而发生马氏体转变。含Cu、V的高铬耐磨铸铁在亚临界处理过程中要析出。一Cu相和VC，使材料由于弥散强化而硬度提高。由于Cu和VC的析出需要一定的时间，故由它们析出引起的二次硬化峰要迟于由于马氏体转变引起地二次硬化峰。用深冷处理后的试样进行对比亚临界处理也证实了高铬耐磨铸铁在亚临界处理中的第一个硬化峰是由马氏体转变引起的，并且深冷处理后，试样由于其残部分余奥氏体转变为马氏体而硬化。更多还原

【Abstract】 In the microstructures of as-cast High Chromium Cast Irons (HCCIs), there is the eutectic type M7C3 carbide that has high hardness, doesn’t join into net and is isolated distribution in the matrix, which has high strength and good toughness. The HCCIs have excellent wear resistance because it’s particular microstructure and being widely applied in the miner areas, metallurgy, manufacture of building materials, power plant and chemical industry and so on. The as-cast HCCIs have not well abrasion resistance and they must be properly heat-treated, then has the finer wear resistance, commonly. The sub-critical treatment is an appropriate heat treatment method and through it, the HCCIs have good mechanical properties. With the development of industry technology, the alloying elements are added into HCCIs to achieve favorable performance .The study on the effect of the alloying element on solidification microstructure and the sub-critical treat hardening behavior of HCCIs is needed for reasonably and availably utilization of the precious alloy resource. Our task is to study the effects of manganese, copper and vanadium on the HCCIs through some contrastive experiment.In this paper, the solidification microstructure and sub-critical heat treatmenthardening behavior of a series of different composition HCCIs has been researched by using electron probe analyzer, X-ray diffraction, SEM, DTA, magnetic method and hardness test, and the influence of different content of manganese, copper and vanadium on HCCIs is gone into particular.The results indicate that, the microstructure of as-cast HCCIs is composed with austenite, martensite and type MiCj, carbide. And with the manganese, copper, or vanadium is added into HCCIs, the retained austenite of the HCCIs increases based on distinct mechanism, respectively. Copper can increase the amount of carbide when it been added into HCCIs and vanadium can fine the microstructure of HCCIs that can bring on HCCIs hardening. HCCIs will appear secondary hardening in the sub-critical treatment, and the more austenite content HCCIs have, the more obvious the phenomenon is. The mechanism of secondary hardening is that with the precipitation of carbide from austenite, the Ms point of HCCIs increase, and occurs martensite transformation and hardening in the course of cooling. The HCCIs contented copper or vanadium will precipitation the e-Cu phase or VC, respectively, in the process of sub-critical treatment, which will lead to dispersion strengthening and HCCIs hardening. Because the precipitation of e-Cu or VC will last longer time, the secondary hardening peak owing to that will posterior to the first hardening peak due to martensite transformation. Through experiment with the cryogenic treated sample also confirm that the first hardening peak of hardening curve results from martensite transformation. And through cryogenic treatment, the hardness of HCCIs augments as a result of retained austenite changed into martensite.更多还原