渗碳温度对18CrNiMo7-6齿轮钢渗碳层组织和硬度的影响

Effect of carburizing temperature on the microstructure and hardness of carburized layer of 18CrNiMo7-6 gear steel

  • 摘要: 渗碳温度的合理选择是提高渗碳效率和获取良好的渗碳层组织和性能的关键因素之一。本文以18CrNiMo7-6齿轮钢为研究对象,使用有限元法模拟了920~960 ℃范围内渗碳温度对渗碳层碳扩散行为的影响规律,并通过电子背散射衍射(EBSD)技术对渗碳层内碳化物种类和含量进行了定量分析。结果表明,随着渗碳温度的增加,试样表面碳浓度几乎没有变化,但试样内部的碳浓度显著增加,渗碳温度的增加可以有效提高渗碳层深度。18CrNiMo7-6齿轮钢的碳化物主要由M23C6,M7C3和渗碳体组成,随着渗碳温度的增加,渗碳层内碳化物含量和尺寸均显著增加。与940 ℃渗碳相比,960 ℃渗碳渗碳层深度增加了0.9 mm,表面渗碳层硬度增加了43.1 HV1。

     

    Abstract: The reasonable selection of carburizing temperature is one of the key factors to improve carburizing efficiency and obtain favorable microstructure and properties of the carburized layer. In this paper, taking 18CrNiMo7-6 gear steel as the research object, the finite element method was used to simulate the influence of carburizing temperature in the range of 920~960 ℃ on the carbon diffusion behavior in the carburized layer, and electron backscatter diffraction (EBSD) technology was employed to quantitatively analyze the types and contents of carbides in the carburized layer. The results show that with the increase of carburizing temperature, the carbon concentration on the sample surface remains almost unchanged, but the carbon concentration inside the sample increases significantly, and the increase of carburizing temperature can effectively improve the depth of the carburized layer. The carbides of 18CrNiMo7-6 gear steel are mainly composed of M23C6, M7C3 and cementite. As the carburizing temperature increases, both the content and size of carbides in the carburized layer increase significantly. Compared with carburizing at 940 ℃, carburizing at 960 ℃ increases the depth of the carburized layer by 0.9 mm and the hardness of the surface carburized layer by 43.1 HV1.

     

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