取向硅钢低温加热工艺中渗氮工序的实验与数值模拟研究

发布时间：2018-03-01 22:31

  本文关键词： 取向硅钢 数值模拟 渗氮 动力学 扩散　出处：《金属学报》2017年06期 　论文类型：期刊论文

【摘要】：通过在实验室模拟取向硅钢的渗氮生产工序,实测了不同渗氮时间下的渗氮量,并通过EPMA、FESEM等观察了渗氮后氧化层的变化、N在硅钢带厚度方向的浓度梯度。根据实测的组织形貌和渗氮动力学特点,首次建立了针对取向硅钢的渗氮动力学模型,并成功地进行了数值模拟计算。研究结果表明:(1)取向硅钢带的平均N含量在渗氮初期增加缓慢,之后逐渐加快,直至90 s时渗氮速率达到最大值之后保持恒定;在750℃渗氮2 min时间内,在近表面0.04 mm范围内存在显著的N浓度梯度;(2)脱碳退火后,取向硅钢的氧化层主要为层状氧化物,渗氮时氧化层被H2还原,层状氧化物转变为球状,氧化层的变化对渗氮动力学影响显著;(3)分析了N由气相穿过表面氧化层至Fe基体的传质系数所遵循的可能模型,发现只有当传质系数遵循氧化层还原动力学模型时,即Avrami函数模型f=A(1-exp(-ktn)),计算结果才能与实测的渗氮动力学特征高度吻合。
[Abstract]:By simulating the nitriding process of oriented silicon steel in laboratory, the nitriding amount under different nitriding time was measured. The concentration gradient of the oxide layer in the direction of the thickness of silicon steel strip was observed by EPMA-FESEM. According to the measured microstructure and nitriding kinetics, the nitriding kinetics model for oriented silicon steel was established for the first time. The numerical simulation results show that the average N content increases slowly at the beginning of nitriding, then accelerates gradually, until the nitriding rate reaches the maximum at 90 s and keeps constant. During nitriding at 750 鈩，

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