Microstructure-informed crystal plasticity finite element models have shown great promise in predicting plastic and creep deformation in polycrystalline materials. These models can provide substantial insight into the design, fabrication and lifetime assessment of critical metallic components during operation, for instance, in thermal power plants. However, to correctly incorporate damage prediction into models, the microstructural strain simulated at the grain level must be accurately predicted with suitable validation. For this reason, a 3D X-ray Diffraction (3DXRD) experiment was carried out on 316H stainless steel, a material commonly used in thermal power plants, to obtain the per-grain strain response during plastic and creep deformation at 550°C. Several hundred grains within a probed X-ray volume were tracked and measured whilst loading in-situ, obtaining per-grain centre-of-mass positions, crystallographic orientations, and average lattice strain over individual grains. These data were used to calibrate a crystal plasticity model to study the plastic and creep deformation using macroscopic stress-strain and stress-relaxation data. Subsequently, the model was used to predict the average elastic strain in different grains during the cyclic creep experiment, which was validated by 3DXRD datasets. The model results reveal that {100} or {311} grain families are strongly sensitive to microstructure, thereby a polycrystal model that describes specific orientation and neighbourhood characteristics is essential to predict the local response of these grain families. Whereas, self-consistent models are suitable for {110} and {111} grain families. This study shows that only with a suitable calibration of subsurface grain behaviour, crystal plasticity models reveal grain characteristic-dependent micromechanical behaviour.

中文翻译：

---

使用 3DXRD 和晶体塑性建模研究塑性和蠕变过程中晶格应变的晶粒解析演化


基于微观结构的晶体塑性有限元模型在预测多晶材料的塑性和蠕变变形方面显示出了巨大的前景。这些模型可以深入了解运行期间（例如火力发电厂）关键金属部件的设计、制造和寿命评估。然而，为了正确地将损伤预测纳入模型中，必须通过适当的验证来准确预测在晶粒水平上模拟的微观结构应变。为此，对火电厂常用材料316H不锈钢进行了3D X射线衍射（3DXRD）实验，以获得550℃下塑性和蠕变变形过程中的每晶应变响应。在原位加载的同时，对探测的 X 射线体积内的数百个晶粒进行跟踪和测量，获得每个晶粒的质心位置、晶体取向和单个晶粒的平均晶格应变。这些数据用于校准晶体塑性模型，以使用宏观应力应变和应力松弛数据研究塑性和蠕变变形。随后，该模型用于预测循环蠕变实验期间不同晶粒的平均弹性应变，并通过 3DXRD 数据集进行了验证。模型结果表明，{100} 或 {311} 晶粒族对微观结构非常敏感，因此描述特定取向和邻域特征的多晶模型对于预测这些晶粒族的局部响应至关重要。然而，自洽模型适用于 {110} 和 {111} 颗粒族。 这项研究表明，只有对地下晶粒行为进行适当的校准，晶体塑性模型才能揭示晶粒特征相关的微机械行为。