The susceptibility of pipeline steels to hydrogen embrittlement, which can significantly impair mechanical performance, especially fracture toughness, is a critical issue in infrastructure integrity This study evaluates the fracture toughness of modern and vintage API X65 steels under cathodic polarization (CP) conditions, employing methods such as rising displacement testing, stepwise rising constant load testing, and constant load testing. Tearing crack growth was detected at crack tip opening displacements (CTODs) of 0.032 to 0.055 mm while subsequent crack arrest under constant force loading was observed with CTOD thresholds of 0.148 mm and 0.255 mm for modern and vintage X65, respectively. Electron channelling contrast imaging demonstrated that arrested cracks in both steels exhibited reduced plasticity and a higher propensity for crack branching compared to propagating cracks. These findings highlight the need for tailored strategies to mitigate the effects of hydrogen embrittlement in pipeline materials and underscore the differences in damage tolerance between steel generations.

中文翻译：

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使用先进的测试方法评估原位电化学充氢下老式和现代 X65 管线钢的断裂韧性

管线钢对氢脆的敏感性会严重损害机械性能，尤其是断裂韧性，是基础设施完整性的一个关键问题本研究评估了现代和老式 API X65 钢在阴极极化 (CP) 条件下的断裂韧性，采用的方法如上升位移试验、逐步上升恒载荷试验、恒载荷试验等。在裂纹尖端张开位移 (CTOD) 为 0.032 至 0.055 毫米时检测到撕裂裂纹扩展，而现代和老式 X65 的 CTOD 阈值分别为 0.148 毫米和 0.255 毫米，随后在恒定力载荷下观察到裂纹停止。电子沟道对比成像表明，与传播裂纹相比，两种钢中的抑制裂纹表现出塑性降低和裂纹分支倾向更高。这些发现强调需要制定量身定制的策略来减轻管道材料氢脆的影响，并强调各代钢在损伤容限方面的差异。