This work investigates the heterogeneous deformation and failure of HR3C austenitic stainless steel welded joints at room and typical service temperatures. Such types of welded joints are widely used in the new generation of fossil fuel power stations and are known to suffer from premature high temperature failure. Observation of in-service failures revealed that cracks may nucleate either in the heat affected zone or in the weld metal. The main objective of this work is to identify the local microstructural conditions and stress–strain fields responsible for both ductile failure and micro-crack nucleation within the weldment at low and high temperatures, respectively. To that purpose, a novel multi-scale micromechanics-based modelling framework is proposed. It relies on representative weld microstructure models digitally reconstructed from electron backscatter diffraction measurements, and dislocation density-based crystal plasticity models to describe the behaviour of individual grains in each weld region. A novel thermo-dynamically consistent relation for the configuration stored energy per unit volume is derived from the crystal plasticity framework.

中文翻译：

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奥氏体不锈钢焊接接头局部储存能量密度驱动的异质变形场和裂纹萌生的微观力学研究

这项工作研究了 HR3C 奥氏体不锈钢焊接接头在室温和典型使用温度下的不均匀变形和失效。这种类型的焊接接头广泛用于新一代化石燃料发电站，并且众所周知会遭受过早的高温失效。对使用中故障的观察表明，裂纹可能在热影响区或焊缝金属中成核。这项工作的主要目标是确定分别在低温和​​高温下导致焊件内延性失效和微裂纹形核的局部微观结构条件和应力应变场。为此，提出了一种新颖的基于多尺度微力学的建模框架。它依赖于根据电子背散射衍射测量数字重建的代表性焊缝微观结构模型，以及基于位错密度的晶体塑性模型来描述每个焊缝区域中单个晶粒的行为。从晶体塑性框架导出了每单位体积构型存储能量的新颖热力学一致关系。