奥氏体不锈钢敏化动力学过程模拟

SIMULATION OF DYNAMIC SENSITIZATION PROCESS OF AUSTENITE STAINLESS STEEL

奥氏体不锈钢的敏化过程实质上是过饱和奥氏体沿晶界析出碳合化物(Fe、Cr)(23)_Co、同时溶质Cr、Ni和C在基体中重新分布的过程。本文作者对此进行了计算机模拟。模拟中认为;碳化物的析出过程受代位溶质的扩散控制,碳化物和奥氏体的界面达到动态的热力学平衡。在动态提供Fc-Cr-Ni-C多元系相平衡信息的条件下,确定扩散过程的边值;求解溶质在基体中的分布曲线;进而可以预测不锈钢的温度-时间-敏化(TTS)曲线.这一模型在奥氏体不锈钢中进行了具体应用和分析讨论,为不锈钢晶间腐蚀的贫铬理论提供了定量的理论依据。

The sensitization process of austenitic stainless steel in, indeed, the one during which carbide (Fe, Cr)_(23)C_6 precipitates along grain boundaries from the oversaturated austenite, and meanwhile, solute atoms, such as Cr, Ni and C, redistribute in the matrices.This process is simulated by computer calculation as reported in this paper.It is considered that the precipitation of the carbide is controlled by the diffusion of substitutional solute atoms, and the interface between the austenite and carbide can reach a thermodynamic equilibrium at a time.Through a dynamic supply of phase equilibrium information in Fe-Cr-Ni-G system, the boundary conditions of the diffusion process are determined; the distribution curves of solutes in the matrices are solved; and still further, the Temperature-Time-Sensitization (TTS) curves are predicted.The practical application of the above simulation has been conducted in austenitic stainless steels.A quantitative theoretical basis has been provided for the Cr-depleted theory on intergranular corrosion.