以随机过程理论为基础, 结合实验数据和分析结果, 提出了基于非齐次Poisson过程和非定态Gamma过程的点蚀萌发和生长建模方法, 建立了一套系统的关于镍基690合金蒸汽发生器传热管点蚀失效的实验方法、建模方法和仿真方法. 对由点蚀引起的镍基690合金蒸汽发生器传热管破损失效的衰退过程进行了有效仿真, 得到了不同工作环境下镍基690合金蒸汽发生器传热管的寿命概率分布. 结果表明, 在不考虑传热管内具体流体动力学和辐照因素的前提下, 本文建立的点蚀引起的衰退过程模型可有效地模拟镍基690合金蒸汽发生器传热管的点蚀萌发和生长, 对预测其寿命和制定相关的维修计划具有重要的参考价值.
Pitting corrosion is one of the most serious modes of localized corrosions that can cause deteriorations of Ni-based alloy 690 steam generator tubes. Because the initiation and propagation of pitting are subject to interactions of different factors, it is a stochastic process. It is almost impossible to draw any deterministic models for formations of the processes. To efficiently model the formation process of pitting, firstly, experimental schemes of pitting formations were designed. Based on stochastic theory, combined experimental data and analyzing results, a modeling method was presented with stochastic processes. Namely, non-homogeneous Poisson process (NHPP) was used to model the pitting initiation process and non-stationary Gamma model was used to set up pitting propagation model. A systemic method was built for pitting corrosion failure of the Ni-based alloy 690 tubes, including experimental method, modeling method and simulation method. Finally, the stochastic degradation failure of the Ni-based alloy 690 tubes was simulated. The probability distribution of the lifespan of the Ni-based alloy 690 tubes was obtained under different working environments. The results showed that the proposed modeling method is valid to analyze the initiation and propagation of pitting of the tubes according to different combinations of modeling parameters. It is important for the lifespan prediction and development of relevant maintenance plans of the tubes.
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