Abstract Tensile tests in high-temperature air with pre-charged hydrogen and elastic plastic fracture mechanics tests in hydrogenated high-temperature water (HTW) at 250 and 288 °C on low-alloy reactor pressure vessel (RPV) steels revealed a clear but moderate reduction of ductility and fracture resistance, respectively. The observed behaviour is a consequence of synergistic effects between hydrogen embrittlement (HE) and the dynamic strain ageing (DSA), in which the HE was amplified by a high DSA susceptibility. The deformation microstructures in the vicinity of the crack tips in air and HTW of two RPV steels with high DSA susceptibility were characterized in detail. These investigations support the idea that the environmental degradation of fracture resistance in hydrogenated HTW was mainly due to the plasticity localization by the interaction between DSA and hydrogen in RPV steels. Synergistic effects of DSA and hydrogen lead to heterogeneous distribution of dislocations and formation of dislocation cells inside bainitic laths.

中文翻译：

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动态应变时效和氢对高温水环境中低合金 RPV 钢断裂行为的协同作用的显微组织表征

摘要 预充氢的高温空气拉伸试验和 250 和 288 °C 加氢高温水 (HTW) 中低合金反应堆压力容器 (RPV) 钢的弹塑性断裂力学试验表明分别降低延展性和抗断裂性。观察到的行为是氢脆 (HE) 和动态应变时效 (DSA) 之间协同效应的结果，其中 HE 被高 DSA 敏感性放大。详细表征了两种具有高 DSA 敏感性的 RPV 钢在空气和 HTW 中裂纹尖端附近的变形显微组织。这些研究支持了以下观点，即氢化 HTW 中抗裂性的环境退化主要是由于 RPV 钢中 DSA 和氢之间的相互作用导致塑性局部化。DSA 和氢的协同作用导致位错的不均匀分布和贝氏体板条内位错单元的形成。