激光氮化过程中热力效应分析

Thermal Stress Analysis During Laser Nitriding

激光氮化过程中产生的拉伸热应力,是导致氮化层开裂和性能下降的重要原因。通过建立三维有限元模型,分析工艺热应力的分布规律,发现危险的最大拉伸热应力出现在氮化层与基体结合处,并且更容易以纵向裂纹的形式释放。进一步基于基体约束作用和工艺环境对热应力的影响,提出了降低拉伸热应力、改善氮化质量的两种工艺方案:基体预热和外施载荷,为激光氮化工艺的推广和工业应用奠定基础。

The tensile thermal stress produced in the process of laser nitriding, was an important factor of performance degradation and cracking in nitriding layer. Three-dimensional finite element models were established to analyze the distribution of thermal stress. The simulation results indicate that the maximum tensile thermal stress appears in the junction of nitriding layer and matrix. The dangerous tensile stress can be released in the form of longitudinal crack more easily. Furthermore, based the influence of the constraints of matrix and process environment on thermal stress, two process programs of preheating and applied load were put forward to reduce the tensile thermal stress and improve the nitriding quality. This will lay the foundation for the future promotion and industrial application of laser nitriding process.