GCr15轴承钢球化处理工艺及其奥氏体化研究

发布时间：2018-02-17 05:08

  本文关键词： GCr15轴承钢 球化 奥氏体化 碳化物溶解 碳化物粗化 晶粒长大　出处：《上海交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：滚动轴承是机械装备的关键基础件,其使用寿命与热处理有着密切的关系。GCr15轴承钢是使用最为广泛的高碳铬轴承钢,本文围绕GCr15轴承钢热处理工艺的制订,采用光学显微镜、扫描电子显微镜、力学性能测试等方法,研究了GCr15轴承钢的球化处理工艺和奥氏体化工艺。为了获得细小、圆整、均匀分布的碳化物颗粒,以高温固溶为预处理手段,系统研究了加热温度、保温时间及冷却方式对高温回火和低温双相退火两类球化工艺所得组织中碳化物颗粒的形貌及尺寸分布的影响,并探讨了两类工艺的球化机制。高温回火工艺的球化机制主要为淬火马氏体在高温回火过程中碳化物的析出、长大与球化,最佳工艺参数为740℃×2 h;低温双相退火工艺的球化机制主要是在低温双相奥氏体区的初步球化和随后离异共析转变过程中的进一步球化,最佳奥氏体化工艺参数为780℃×30 min,离异共析转变工艺参数为25℃/h连续退火或720℃×4 h等温退火。奥氏体化过程中碳化物的溶解、粗化和奥氏体晶粒的长大对GCr15轴承钢的最终组织性能有很大影响。本文通过碳化物溶解与粗化过程的迭代计算,建立了碳化物的溶解与粗化模型,并能够较准确地预测奥氏体化过程中碳化物颗粒的平均粒径和体积分数变化;此外,本文在试验基础上研究了奥氏体晶粒的长大规律,当奥氏体化温度低于900℃时,由于未溶碳化物颗粒的阻碍,晶粒尺寸随奥氏体化温度和保温时间的变化较小。最后,本文研究了固溶-高温回火、固溶-连续退火和固溶-等温退火三种球化工艺对淬回火后组织与性能的影响。与传统球化工艺相比,三种球化工艺均能有效提高GCr15轴承钢的抗弯强度,其中固溶-连续退火工艺为最佳工艺。
[Abstract]:Rolling bearing is the key part of mechanical equipment, and its service life is closely related to heat treatment. GCr15 bearing steel is the most widely used high carbon chromium bearing steel. In this paper, the heat treatment process of GCr15 bearing steel is formulated and optical microscope is used. The spheroidization and austenitization of GCr15 bearing steel were studied by means of scanning electron microscope (SEM) and mechanical property test. In order to obtain fine, round and uniformly distributed carbide particles, high temperature solution was used as the pretreatment method. The effects of heating temperature, holding time and cooling mode on the morphology and size distribution of carbides in the spheroidized microstructure obtained by high temperature tempering and low temperature dual phase annealing were systematically studied. The spheroidization mechanism of two kinds of processes is discussed. The spheroidization mechanism of high temperature tempering process is mainly the precipitation, growth and spheroidization of quenched martensite during high temperature tempering. The optimum technological parameters are 740 鈩，

本文编号：1517290