蠕墨铸铁喷吹法蠕化处理工艺研究

发布时间：2018-04-01 02:06

本文选题：蠕墨铸铁　切入点：喷吹法　出处：《山东理工大学》2015年硕士论文

【摘要】：蠕墨铸铁具有独特优异性能,在增压柴油机缸体、缸盖及铁路机车制动器等方面有较大应用,是铸铁材质发展方向之一。近年来,蠕墨铸铁得到了很快的发展,其生产工艺也在不断改进。本论文结合喷吹法球化铁液的经验和冲入法蠕化铁液的优点,归纳出一种喷吹法蠕化铁液的处理工艺。以钝化镁粒配以少量稀土镁硅铁合金作为蠕化剂,分析两种蠕化剂不同配比对石墨形态变化的影响;探索Mg元素加入量、孕育效果、铸件壁厚对蠕化率的影响,铁液温度对镁元素吸收率的影响,提出适合喷吹法的合理的蠕化工艺参数;采用倒置金相显微镜观察片状石墨、蠕虫状石墨和球状石墨在二维形态上的差别,蠕墨铸铁深度腐蚀后,采用场发射扫描电子显微镜观察蠕虫状石墨的三维形貌;对比研究喷吹法和冲入法制取蠕铁时对其组织和性能所产生的差别,包括蠕化稳定性、石墨形态、蠕化率、珠光体含量、力学性能等。研究发现,用钝化镁粒配以少量稀土合金处理铁液时可以获得好的蠕化效果,可以大幅降低稀土类蠕化剂的加入量,降低生产成本。铸件蠕化率与铸件壁厚有关,随着壁厚增加,蠕化率呈增大趋势,铸件冷却速度越快,越容易促进球状石墨的形成。试验结果表明,喷吹法处理蠕铁,蠕化稳定性较好,蠕虫状石墨形态好,石墨分布均匀,蠕化率较高,力学性能良好,能达到RuT350牌号的要求;喷吹法是在相对密闭的包内对铁液进行处理,相对于冲入法而言,减少了空气污染;喷吹法是一种制取高蠕化率铸铁件的有效方法之一。
[Abstract]:Vermicular graphite cast iron is one of the developing directions of cast iron due to its unique excellent properties and its application in the cylinder block, cylinder head and brake of railway locomotive, etc. In recent years, vermicular graphite cast iron has been developed rapidly. This paper combines the experience of nodulizing molten iron with injection and the advantages of compacted molten iron by impinging method. A treatment process of vermicular molten iron by injection is summarized. With passivated magnesium particles and a small amount of rare earth magnesium-silicon ferroalloy as vermicularizing agent, the influence of the two compacted agents on the morphology of graphite is analyzed, and the addition amount of mg element and the inoculation effect are explored. The effect of casting wall thickness on vermicularizing rate and the effect of molten iron temperature on absorption of magnesium element were studied. The reasonable vermicular process parameters suitable for injection method were put forward, and the flake graphite was observed by inverted metallographic microscope. The difference between vermicular graphite and nodular graphite in two-dimensional morphology. The 3D morphology of vermicular graphite was observed by field emission scanning electron microscope after deep corrosion of vermicular graphite. The differences in microstructure and properties of vermicular iron produced by injection method and impinging method were compared, including vermicular stability, graphite morphology, vermicular rate, pearlite content, mechanical properties, etc. A good vermicularizing effect can be obtained when the passivated magnesium particles are mixed with a small amount of rare earth alloy to treat the molten iron. The addition of rare earth compacting agents can be greatly reduced and the production cost can be reduced. The compactness rate of castings is related to the wall thickness of castings and increases with the increase of wall thickness. The rate of vermicularization is increasing, and the faster the cooling rate of casting is, the easier it is to promote the formation of spheroidal graphite. The experimental results show that the vermicular graphite has good vermicular stability, good morphology of vermicular graphite, uniform distribution of graphite and higher vermicular rate of vermicular iron. The mechanical properties are good and can meet the requirements of RuT350 grade, the injection method is to treat the molten iron in a relatively closed bag, and the air pollution is reduced compared with the washing method, and the injection method is one of the effective methods for producing high compactness cast iron.
【学位授予单位】：山东理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG250

【相似文献】