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针对316L奥氏体不锈钢表面强化,进行了低温表面渗碳实验并测量了渗后试样渗碳层内C浓度沿深度方向的分布.建立了以“陷阱-去陷阱”质量传递机制为基础的动力学模型,认为Cr原子在C的扩散过程中对C原子具有陷阱作用,利用该模型计算出渗后试样中C浓度沿渗层深度方向的分布,并与实验结果进行比较.结果表明,实验测得的C浓度沿渗层深度方向的分布形状呈现凸状,与简单Fick定律得出来的结果不同,而基于“陷阱-去陷阱”模型得到的计算结果与实验结果符合较好,表明陷阱作用在C扩散过程中起重要作用.Cr原子通过对C原子陷阱作用,降低C的扩散系数,对实验数据拟合得到C的去陷阱激活能为165 k J/mol.所提出模型仅适用于未发生碳化物析出的低温渗碳,且并未考虑扩散应力的影响.
Aiming at the surface strengthening of 316L austenitic stainless steel, the low temperature surface carburizing experiment was carried out and the C concentration distribution in the carburized layer of the infiltrated sample was measured along the depth direction. The mechanism of the mass transfer mechanism of “trap-to-trap” Based on the kinetic model, it is considered that the Cr atom has a trapping effect on the C atom in the diffusion process of C, and the distribution of C concentration along the depth of the diffusion layer is calculated by the model and compared with the experimental results. The experimental results show that the distribution of C concentration along the depth of the layer shows a convex shape, which is different from that obtained by the simple Fick’s law. The calculated results based on the “Trap-Trap” model are in good agreement with the experimental results Well, it shows that the trap function plays an important role in the diffusion process of C. The Cr atom can reduce the diffusion coefficient of C by C trap, and the activation energy of trapping to C is 165 kJ / mol. The model is only suitable for low temperature carburizing without carbide precipitation and does not consider the effect of diffusion stress.