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为探索温度可控的大功率半导体激光器作用下非平衡态的奥氏体转化温度和马氏体临界转化速度两个条件同时对中碳钢的相变硬化的作用机理,本文利用温度可控的大功率半导体直接输出激光加工系统对45钢进行温度控制模式下的激光相变硬化实验。实验表明:在相同激光相变硬化控制温度下,随着扫描速度的增加,相变硬化层深度先增加后降低。对试样的显微组织分析表明,在扫描速度较慢时,受冷却速度影响产生的激光相变硬化区成分、组织的差异是造成硬化层深度和硬度不同的原因。并基于非平衡态的奥氏体转化温度和马氏体临界转化速度为马氏体生成的判断依据,建立了基于COMSOL Multiphysics软件的三维激光相变硬化数值分析模型,探讨了温度控制模式下激光加工参数对硬化层深度的影响,与实验结果对比发现该模型能够较为准确预测温度可控的激光相变硬化层深度。
In order to explore the mechanism of transformation hardening of non-equilibrium austenite and martensite at the same time on the transformation hardening of medium carbon steel under the action of high-power semiconductor laser controlled by temperature, High-power semiconductor direct output laser processing system of 45 steel temperature control mode laser phase-change hardening experiments. Experiments show that: with the same laser phase change hardening temperature control, with the increase of scanning speed, the depth of phase transformation hardening layer first increases and then decreases. The microstructure analysis of the samples shows that the composition and the microstructure of the laser transformation hardening zone caused by the cooling rate are the causes of the different depth and hardness of the hardened layer when the scanning speed is slow. And based on the non-equilibrium austenite transformation temperature and martensite critical transformation rate as the basis for the determination of martensite, the COMSOL Multiphysics software based on the three-dimensional laser phase-change hardening numerical analysis model was discussed in the temperature control mode laser The effects of processing parameters on the depth of hardened layer are compared with the experimental results. The results show that the model can accurately predict the depth of laser-induced hardened layer.