热处理工艺对城轨轴承用钢组织和性能的影响研究

发布时间：2018-05-23 17:45

  本文选题：轴承 + 显微组织　； 参考：《大连交通大学》2014年硕士论文

【摘要】：近年来,高速铁路和城市轨道交通业高速发展,这些行业需要大量的使用各类轴承,对轴承的性能要求也随之提高。然而对于轴承的许多关键零部件一般仍依赖进口,所以很有必要开发自主知识产权的高性能轴承。本文首先选用企业常用的等温淬火工艺制备了一套轴承,对自制的GCr15滚子和GCr18Mo内外圈三个部件进行了全面的检测,包括成分、硬度、组织、残余应力分布等,并分析该工艺对材料组织和性能的影响；然后在成品件的分析基础上对使用的这两种轴承钢材料进行了预备热处理和最终热处理,探讨不同的热处理工艺对材料组织和性能的影响,为提高城轨车辆用轴承的使用寿命提供重要的实验数据。研究发现：三个部件表面至心部组织及硬度均匀一致。轴承的滚子、内圈、外圈的平均硬度分别为56.2HRC、59.9HRC和60.8HRC。轴承各部件主要组织由下贝氏体和碳化物组成,但内外圈中的下贝氏体组织和碳化物都比滚子中的细小,滚子中下贝氏体针长宽比约为7.5,内外圈中下贝氏体针长宽比约为10。滚子、内圈和外圈碳化物的平均直径分别约为0.55μm、0.39μm和0.42μm,其中直径(0.2-0.8)μm碳化物所占比例分别约为86.5%、88.2%和93.2%。三部件碳化物占轴承组织的比例为一致,都约为10%。滚子、内圈外表面均处于残余压应力状态,表面的应力状态均是压应力且轴向压应力大于环向。滚子和内圈热处理后轴向和环向压应力平均值分别约为-480MPa和-90MPa,-588MPa和-390MPa；热处理抛光后轴向和环向压应力平均值分别约为-398MPa和-61.5MPa,-483MPa和-231MPa。 GCr18Mo轴承钢三周期球化退火后球化效果都比较理想,对最终热处理后两种轴承钢组织及硬度的分析可以得出：两试样的组织均是由回火马氏体+碳化物+残余奥氏体组成,GCr15和GCr18Mo轴承钢分别在840℃淬火160℃回火和860℃淬火180℃回火时的硬度值最高。
[Abstract]:In recent years, the high-speed railway and urban rail transit industry develop rapidly, these industries need to use a large number of bearings, the performance of the bearing requirements are also improved. However, many key parts of bearings are still imported, so it is necessary to develop high performance bearings with independent intellectual property rights. In this paper, a set of bearings was prepared by using the isothermal quenching process commonly used in enterprises. The three components of GCr15 roller and GCr18Mo inner and outer ring, including composition, hardness, microstructure, residual stress distribution and so on, were tested comprehensively. The effect of the process on the microstructure and properties of the bearing steel is analyzed, and then the two kinds of bearing steel materials used are treated with preparatory heat treatment and final heat treatment on the basis of the analysis of the finished parts. The effects of different heat treatment processes on the structure and properties of materials are discussed, which provide important experimental data for improving the service life of bearings for urban rail vehicles. The results show that the microstructure and hardness of the three parts are uniform and uniform. The average hardness of roller, inner ring and outer ring of bearing are 56.2 HRC 59.9HRC and 60.8 HRC respectively. The main structure of bearing components is composed of lower bainite and carbide, but the lower bainite structure and carbides in inner and outer ring are smaller than those in roller. The ratio of length to width of lower bainite needle in roller is about 7.5, and that of lower bainite needle in inner and outer ring is about 10. The average diameters of roller, inner ring and outer ring carbides are about 0.55 渭 m 0.39 渭 m and 0.42 渭 m respectively, in which 0.2-0.8) 渭 m carbides account for 86.5% and 93.2%, respectively. The proportion of three component carbides to the bearing structure is consistent, about 10%. The inner and outer surface of the roller are in the state of residual compressive stress, and the stress state of the surface is compressive stress and the axial compressive stress is larger than the circumferential stress. The average axial and toroidal compressive stresses of roller and inner ring after heat treatment are about -480 MPA and -90 MPA and -390 MPA respectively, and the average values of axial and circumferential compressive stresses after heat treatment are about -398 MPA and -61.5 MPA / 483 MPA and -231 MPA, respectively. The spheroidization effect of GCr18Mo bearing steel after three cycle spheroidizing annealing is ideal. By analyzing the microstructure and hardness of the two bearing steels after final heat treatment, it can be concluded that the microstructure of the two specimens is composed of tempered martensite carbide residual austenite and GCr18Mo bearing steel quenched at 840 鈩，

本文编号：1925717