In this work, a physics-based crystal plasticity model is developed to predict failure in Grade 91 steel. A microstructure-sensitive dislocation kinetics law defines local plastic slip, an Arrhenius creep law is used to model vacancy-mediated plasticity, and strain hardening evolves with local dislocation density. As voids nucleate, a reaction–diffusion framework is adopted to dynamically track the local void size distributions, which grow by coupled viscoplastic and diffusive processes. Upon accurately reproducing the temperature and stress dependencies in primary, secondary, and tertiary creep seen experimentally for Grade 91 steel, the model is exercised to generate a material response database across a wide range of operating conditions. A new reduced-order lifetime predictor is developed from numerical predictions, and a Bayesian framework is used to quantify prediction uncertainties. When compared to current empirically-derived lifetime relations, the proposed lifetime assessment tool predicts rupture times up to several orders more conservative.

在这项工作中，开发了一种基于物理的晶体塑性模型来预测 91 级钢的失效。微观结构敏感的位错动力学定律定义了局部塑性滑移，阿伦尼乌斯蠕变定律用于模拟空位介导的塑性，应变硬化随局部位错密度而发展。随着空隙成核，采用反应扩散框架来动态跟踪局部空隙尺寸分布，其通过耦合粘塑性和扩散过程而增长。在准确再现 91 级钢的一次、二次和三次蠕变实验中的温度和应力相关性后，该模型将用于生成跨各种操作条件的材料响应数据库。从数值预测中开发出一种新的降阶寿命预测器，贝叶斯框架用于量化预测的不确定性。与当前根据经验得出的寿命关系相比，提议的寿命评估工具预测破裂时间高达几个数量级，更为保守。