镍生铁对灰铸铁组织与性能的影响研究

发布时间：2018-04-09 14:29

本文选题：镍生铁　切入点：镍　出处：《山东建筑大学》2017年硕士论文

【摘要】：灰铸铁凭借其优良的铸造性能、耐磨性、导热性、减震性等性能,被广泛的应用到实际的生产中,例如汽车刹车盘、刹车鼓的生产基本上都是使用的灰铸铁材料。但是,灰铸铁件的力学性能相对较差。目前,人们为了提高灰铸铁的力学性能常用的方法是添加合金元素。但是,近年来合金元素的价格不断的飙升。添加合金元素,势必会带来成本的增加。镍生铁中的低镍生铁是指含有少量镍(1.6%-1.8%)、铬(2%-3%)的一类生铁,它与普通的生铁冶炼方法相似,价格比市面上的普通生铁稍高。本课题以低镍生铁为原材料中的一种,与普通原生铁以及废钢等进行配料来生产灰铸铁件。对灰铸铁试样的力学性能、金相组织、内应力等检测分析,得出以下结论。力学性能方面:随着镍生铁比例的增加(镍、铬含量的增加),抗拉强度呈现出先增加后下降的趋势,硬度呈现出一直上升的趋势。当碳含量为3.4%时,铬含量为0.4%(镍生铁比例为12%)时,力学性能最佳,强度为212MPa,硬度为205HB;当碳含量为3.6%时,铬含量为0.5%(镍生铁比例为14.9%)时,力学性能最佳,强度为204MPa,硬度为198HB;当碳含量为3.8%时,铬含量为0.7%(镍生铁比例为20.8%)时,力学性能最佳,强度为195MPa,硬度为204HB。显微组织方面:随着镍生铁比例(镍、铬含量)的增加,组织中的石墨形态由粗大的A型石墨逐渐的变为细小的A型石墨,基体组织中珠光体逐渐增多,但是随着镍生铁比例(镍、铬含量)的超过一定范围时,开始有D型石墨出现并逐渐增加,基体中开始有自由渗碳体出现并逐渐增加。当碳含量为3.4%时,铬含量为0.4%(镍生铁比例12%)时,石墨形态及基体组织最为理想。当碳含量为3.6%时,铬含量为0.5%(镍生铁比例为14.9%)时,石墨形态及集体组织最为理想。当碳含量为3.8%,铬含量为0.6%(镍生铁比例为17.9%),石墨形态及基体组织最为理想。内应力方面:通过对3大组试样的组织中的内应力检测得出,随着镍生铁比例(镍、铬含量)的增加,组织中的内应力基本呈现出了一直增加的趋势。实际应用方面:镍生铁在生产SG20材质以及HCCM材质的刹车盘中得到了应用,力学性能、石墨形态、基体组织均能满足材质要求并且节约成本,取得了不错的效果。实验结果表明,镍生铁的应用一方面能够促进灰铸铁性能的提升;另一方面,又能够降低生产成本,因此,镍生铁在灰铸铁的熔炼中的应用具有很高的经济效益。
[Abstract]:Gray cast iron is widely used in practical production because of its excellent casting property, wear resistance, thermal conductivity, shock absorption and so on. For example, the production of automobile brake disc and brake drum is basically a kind of gray cast iron material.However, the mechanical properties of gray cast iron are relatively poor.At present, in order to improve the mechanical properties of gray cast iron, the commonly used method is to add alloying elements.But the price of alloy elements has soared in recent years.Adding alloy elements will inevitably lead to an increase in costs.The low nickel pig iron in nickel pig iron is a kind of pig iron containing a small amount of nickel (1.6-1.8). It is similar to the ordinary pig iron smelting method, and its price is slightly higher than that of ordinary pig iron on the market.In this paper, low nickel pig iron is used as a raw material to produce gray cast iron with common raw iron and scrap iron.The mechanical properties, metallographic structure and internal stress of gray cast iron samples are analyzed and the following conclusions are obtained.Mechanical properties: with the increase of the ratio of nickel pig iron (Ni, Cr), the tensile strength increased first and then decreased, and the hardness increased continuously.When the carbon content is 3.4 and the chromium content is 0.4 and the nickel pig iron ratio is 12, the mechanical properties are the best, the strength is 212MPa, the hardness is 205HB. when the carbon content is 3.6g, the chromium content is 0.5 and the nickel pig iron ratio is 14.9.When the carbon content is 3.8, the chromium content is 0.7 and the nickel pig iron ratio is 20.8, the mechanical properties are the best, the strength is 195MPa and the hardness is 204HB.Microstructure: with the increase of the ratio of nickel pig iron (nickel, chromium), the morphology of graphite in the microstructure gradually changed from coarse A type graphite to fine A type graphite, and the pearlite in the matrix gradually increased.However, when the ratio of nickel pig iron (nickel and chromium) exceeds a certain range, the D-type graphite appears and increases gradually, and the free cementite appears and increases gradually in the matrix.When the carbon content is 3.4% and the chromium content is 0.4% (nickel pig iron ratio 12), the graphite morphology and matrix structure are the most ideal.When the carbon content is 3.6 and the chromium content is 0.5 (Ni pig iron ratio is 14.9), the graphite morphology and collective structure are the most ideal.When the carbon content is 3.8% and the chromium content is 0.6% (the nickel pig iron ratio is 17.9%), the graphite morphology and matrix structure are the most ideal.In terms of internal stress, the internal stress in the three groups of samples was detected. It was found that with the increase of the ratio of nickel pig iron (nickel, chromium), the internal stress in the structure showed an increasing trend.Practical application: nickel pig iron has been applied in the brake disc of SG20 material and HCCM material. The mechanical properties, graphite morphology and matrix structure can meet the material requirements and save the cost, and good results have been obtained.The experimental results show that the application of nickel pig iron can improve the properties of gray cast iron on the one hand and reduce the production cost on the other hand. Therefore, the application of nickel pig iron in the smelting of gray cast iron has a high economic benefit.
【学位授予单位】：山东建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG143.2

【相似文献】