自生碳化物颗粒增强铁基复合材料制备及组织性能

发布时间：2018-03-17 21:28

本文选题：原位自生　切入点：铁基复合材料　出处：《河南科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文以钛铁、钒铁、碳粉和20钢为原料,采用原位反应铸造法制备出碳化物颗粒增强铁基复合材料。通过金相显微镜、扫描电子显微镜、透射电子显微镜、X射线衍射仪以及洛氏硬度计和冲击试验机研究了变质处理和热处理工艺对自生复合材料组织和性能的影响。采用MM-200型摩擦磨损试验机研究了干磨损条件下铁基自生复合材料的滑动磨损特性。试验结果表明,采用原位反应铸造法制备了自生碳化物体积分数为18%的变质和未变质两种复合材料。自生复合材料的铸态组织为珠光体+碳化物+少量菊花状石墨+少量铁素体。经RE变质处理后自生复合材料铸态基体组织由片状珠光体和粒状珠光体转变为以粒状珠光体为主。稀土变质处理改变了自生碳化物的生长方式,使自生碳化物由棒状变为颗粒状。碳化物的类型均为VC+TiVC2。变质自生复合材料试样硬度为37.10 HRC冲击韧性为2.7 J/cm2。比未变质自生复合材料分别提高了4.27%和35%。自生复合材料在不同淬火温度下的组织均为马氏体+碳化物+少量残余奥氏体。变质处理能改善自生复合材料基体组织,使自生复合材料组织由变质前的针状马氏体变为针状马氏体和板条马氏体的混合组织,马氏体中析出的二次碳化物颗粒比变质前更加细小规则且含量增多。变质和未变质自生复合材料的硬度均随淬火温度升高而降低,而冲击韧性则随淬火温度升高呈现出了先升高后降低的趋势,在920°C淬火处理后自生复合材料的冲击韧性达到最大值。变质处理对不同温度淬火后自生复合材料的硬度影响不大,但能显著提高自生复合材料的冲击韧性,使自生复合材料的冲击韧性由变质前的9.0J/cm2提高到11.2 J/cm2。920°C淬火处理后变质自生复合材料的断裂类型为准解理断裂,铸态的断裂类型为沿晶断裂。在干滑动磨损条件下自生复合材料的磨损失重量和磨损率均随磨损载荷的增加而增大,经RE变质处理可提高其耐磨性。自生复合材料在不同载荷下的磨损规律不同,当载荷小于600N时磨损失重量缓慢增加;当载荷大于600N时磨损失重量迅速增加。不同载荷下的磨损机理不同,低载荷下自生复合材料的磨损机理主要为磨粒磨损,高载荷下自生复合材料的磨损机理以氧化磨损+磨粒磨损为主。
[Abstract]:In this paper, titanium iron, vanadium iron, carbon steel and 20 as raw materials, preparation of carbide particle reinforced iron matrix composite casting method by in situ reaction. Through metallographic microscope, scanning electron microscope, transmission electron microscope, X ray diffractometer and Rockwell hardness tester and impact tester on the effect of modification and heat treatment on spontaneous microstructure and properties of the composites. The MM-200 were studied under dry friction sliding wear characteristics of iron-based in-situ composite material friction wear testing machine. The test results show that in-situ carbide volume fraction of 18% and two kinds of metamorphic unmodified composites were prepared by in-situ reaction casting. In situ cast microstructure of composite materials for a small amount of pearlite + carbide + graphite + a small amount of ferrite. After RE modification in situ composites as cast microstructure by lamellar pearlite and granular pearlite The change in granular pearlite. Rare earth modification changes the growth pattern of authigenic carbonate, the in-situ carbide rods by granular. The carbides are VC+TiVC2. in-situ composite hardness for metamorphic impact toughness of 37.10 HRC 2.7 J/cm2. ratio unchanged quality composites were increased by 4.27% and 35%. in-situ composite tissue at different quenching temperatures are martensite and carbides and residual austenite. The modification can improve the microstructure of composites, the composites by acicular martensite before modification into mixed microstructure of acicular martensite and lath martensite, increasing two times of precipitated carbide particles in martensite than metamorphic the more fine rules and the content of modification and no modification. In situ composite hardness with quenching temperature increasing, but the impact toughness Increased showing increased first and then decreased with the quenching temperature at 920 DEG C after quenching in situ impact toughness of composites reached the maximum. Modification on different quenching temperature has little influence in situ composite hardness, but can significantly improve the self impact toughness of composite materials, the impact toughness of the composite in situ increased from 9.0J/cm2 to 11.2 J/cm2.920 before the metamorphic degree C quenching metamorphic fracture type composite material for in-situ quasi cleavage fracture, fracture type cast as intergranular fracture. Under the condition of dry sliding wear of composite material self weight loss and wear rate increases with the increase of the wear load by RE. Modification can improve the wear resistance of the composites. Under different load wear different rules, when the load is less than 600N when the loss of weight increases slowly; when the load exceed 600N losses The weight increases rapidly. The wear mechanism under different loads is different. The wear mechanism of in-situ composites under low load is mainly abrasive wear. The wear mechanism of in-situ composites under high load is mainly oxidation wear and abrasive wear.

【学位授予单位】：河南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB333

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