Abstract

The effect of hydrogen on the microdamage evolution of 1200M advanced high-strength steel was evaluated by the combination of experimental and numerical approaches. In the experimental section, the tensile test was performed under different testing conditions, i.e., vacuum, in-situ hydrogen plasma charging (IHPC), ex-situ electrochemical hydrogen charging (EEHC), and ex-situ + in-situ hydrogen charging (EIHC) conditions. The post-mortem analysis was conducted on the fracture surface of specimens to illuminate the impact of hydrogen on the microstructure and mechanical properties. The results showed that under all of hydrogen charging conditions, the yield stress and ultimate tensile strength were slightly sensitive to hydrogen, while tensile elongation was profoundly affected. While only ductile dimple features were observed on the fracture surfaces in vacuum condition, the results indicated a simultaneous action of the hydrogen-enhanced decohesion (HEDE) and hydrogen enhanced localized plasticity (HELP) mechanisms of HE, depending on the local concentration of hydrogen under the IHPC and EEHC conditions. At the EIHC condition, the HEDE model was the dominant failure mechanism, which was manifested by the HE-induced large crack. In the numerical approach, a finite-element analysis was developed to include the Gorson–Tvergaard–Needleman (GTN) damage model in Abaqus™ software. To numerically describe the damage mechanism, the GTN damage model was utilized in the 3D finite-element model. After calibration of damage parameters, the predicted damage mechanisms for two testing conditions, i.e., vacuum and EIHC, were compared with experimental results.

中文翻译：

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氢脆对高级高强度双相钢微损伤演化影响的实验和数值研究

摘要

通过实验和数值方法相结合的方法，评估了氢对1200M高级高强度钢微损伤演变的影响。在实验部分中，拉伸试验是在不同的测试条件下进行的，即真空，原位氢等离子体充电（IHPC），非原位电化学氢充电（EEHC）和非原位+原位氢充电（ EIHC）条件。对样品的断裂表面进行事后分析，以阐明氢对显微组织和力学性能的影响。结果表明，在所有氢充注条件下，屈服应力和极限抗拉强度对氢都稍有敏感，而拉伸伸长率则受到深远影响。虽然在真空条件下在断裂表面上仅观察到韧性的凹痕特征，但结果表明，氢的增强脱粘（HEDE）和氢增强的HE局部可塑性（HELP）机理同时起作用，这取决于氢的局部浓度。 IHPC和EEHC条件。在EIHC条件下，HEDE模型是主要的破坏机制，这由HE引起的大裂纹得以体现。在数值方法中，开发了有限元分析，以在Abaqus™软件中包括Gorson-Tvergaard-Needleman（GTN）损伤模型。为了对损伤机理进行数值描述，在3D有限元模型中使用了GTN损伤模型。在对损伤参数进行校准之后，针对两种测试条件（即真空和EIHC）的预测损伤机理，