高硅固溶强化球墨铸铁的研究

发布时间：2018-01-24 18:32

本文关键词： 球墨铸铁固溶强化抗拉强度铁素体　出处：《兰州理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：球墨铸铁由于其较低的生产成本,良好的力学性能等特点,在工业机械构件中已得到了广泛的应用。这些机械构件主要应用于对材料要求较高的工作条件,如受力比较复杂,较高的强度、较高的韧性和耐磨性等。广泛应用在汽车行业的曲轴、汽缸盖;燃汽轮机行业的进排气缸等零部件上。由于球墨铸铁使用行业的特点,因此对于零部件的产品质量要求也非常高,除常规的力学性能要求外,还要有耐高温或低温、耐腐蚀性、耐机械冲击以及良好的尺寸稳定性等。随着对于球墨铸铁材料的进一步研究,许多铸钢材料、灰口铸铁已经被球墨铸铁所取代,球墨铸铁已发展成为一种非常重要的工程材料。随着科学技术的进一步发展,铸铁生产技术也在不断创新,目前生产的球墨铸铁牌号有QT400-18、QT500-7、QT600-3、QT700-2等材料。QT500-7、QT600-3基体组织中含有30%~60%珠光体,采用此类球墨铸铁的抗拉强度高,但其屈服强度和伸长率较低。另外QT500-7、QT600-3球墨铸铁与QT400-18全铁素体基体球墨铸铁相比,其加工性能比较差,由于基体组织中含有一定量的珠光体,因此对于加工刀具磨损相对其它球墨铸铁磨损较大。为了获得更高抗拉强度、屈服强度、伸长率及更好的加工性能的球墨铸铁,本论文充分利用硅元素的固溶强化作用,选择Ba Si孕育剂对铁液进行孕育处理,Fe Si Mg球化剂对铁液进行球化处理,即通过固溶某种溶质元素来形成固溶体从而强化金属。利用硅元素溶入铁液中形成固溶体,其固溶体中溶质原子造成晶格畸变,从而增加位错运动的阻力,阻碍位错运动,进而增加固溶体的强度与硬度。当溶质原子的浓度处于适当范围时,合金的强度和硬度可以明显提高,但合金的塑形和韧性会降低。试验研究证明,利用硅元素固溶强化,在铁液中保证一定量的硅含量,已经成功的研发出了生产QT500-14、QT600-10全铁素体基体牌号的球墨铸铁工艺方法,获得了较高牌号的球墨铸铁材料,解决了该材料屈服强度、伸长率较低以及加工性能差等问题。
[Abstract]:Nodular cast iron due to its low production cost, good mechanical properties, has been widely used in industrial machinery components. These mechanical components mainly used for materials demanding working conditions, such as stress is complex, high strength, high toughness and wear resistance. The crankshaft. Widely used in the automobile industry of the cylinder cap; the exhaust cylinder and other parts of gas turbine industry. Due to the characteristics of ductile iron industry, so the product quality requirements of parts is very high, in addition to the requirements of the conventional mechanical properties, but also have high temperature or low temperature, corrosion resistance, and good resistance to mechanical shock the size of stability. As for the further study of ductile iron material, many steel, gray cast iron has been replaced by ductile iron, nodular cast iron has become a very important project. The material. With the further development of science and technology, iron production technology is also in constant innovation, the current production of ductile iron grades are QT400-18, QT500-7, QT600-3, QT700-2 and other materials.QT500-7, QT600-3 in the matrix containing 30%~60% pearlite, with high tensile strength such as ductile iron, but its yield strength and elongation is low. The addition of QT500-7, QT600-3 and QT400-18 ductile iron ferrite matrix ductile iron, its processing performance is poor, because contain a certain amount of pearlite in the matrix, so the machining tool wear it relative to the ductile iron wear greatly. In order to obtain a higher tensile strength, yield strength, ductile iron processing performance elongation and better, this paper makes full use of the solid solution strengthening effect of silicon Ba Si inoculants on liquid iron inoculation, Fe Si Mg spheroidizing agent for molten iron spheroidizing treatment, Through some kind of solution to solute to form a solid solution to strengthen the metal. The solid solution is formed of silicon dissolved in liquid iron, the solid solubility of solute atoms caused by lattice distortion in the body, thereby increasing the resistance to dislocation motion, hinder dislocation motion, and increase the strength and hardness of the solution. When the concentration of solute atoms in a proper range, the strength and hardness of the alloy can be improved obviously, but the plasticity and toughness of alloy will decrease. The experimental study proves that the use of silicon element solid solution strengthening, guarantee a certain amount of silicon content in molten iron, has successfully developed the production of QT500-14, QT600-10 ferrite matrix grade ball graphite cast iron process, obtained higher grades of ductile iron material, solves the problem of material yield strength, lower elongation and poor processing performance.

【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG255

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