弹簧钢55SiCrA脱碳规律的研究

Surface decarburization of spring steel 55SiCrA

研究了55SiCrA弹簧钢加热温度和时间对脱碳层深度和组织形貌的影响规律,运用Fick第二定律讨论了脱碳层深度与温度之间的定量关系。结果表明,55SiCrA钢在750～1100℃加热时,其脱碳层深度随着温度的升高逐渐增大,超过1100℃后,脱碳层深度逐渐减少,1100℃时脱碳层深度最深;随着保温时间越长,脱碳层深度呈抛物线增长;与时间相比,脱碳对温度更敏感;在750～850℃加热时,脱碳组织以全脱碳层为主;当温度超过900℃以后,脱碳组织以半脱碳为主,全脱碳层变得很薄,全脱碳厚度基本不随加热温度发生变化,综合考虑各方面影响因素,弹簧钢55SiCrA轧制时的加热温度应为1000～1050℃。

The effect of heating temperature and holding time on the decarburized layer depth during heating process of spring steel 55SiCrA was studied.The law of the morphology evolution of decarbonization microsturcture was analyzed.The quantitative relationship between the decarburization layer depth and temperature was discussed by using Fick’s second law.The results show the decarburization layer depth increases gradually with increasing the temperature when 55SiCrA steel is heated at 750-1100 ℃.The layer depth gradually decreases when the temperature is over 1100 ℃, and there is the largest depth of decarbonization layer at 1100 ℃.With increasing the soak time, the depth of decarburization layer grows as parabolic.Decarburization is more sensitive to temperature than to the time.The major decarburized microstructure is fully decarburized layer at 750-850 ℃.When heating temperature exceeds 900 ℃, the major decarburized microstructure is semi-decarburized layer, the full decarbonization layer becomes thin, and the thickness of the fully decarburized layer can not change with temperature.Considering the various factors, the rolling heating temperature of spring steel 55SiCrA should be at 1000-1050 ℃.