The uptake and accumulation of hydrogen in materials during a service process is the primary prerequisite of hydrogen embrittlement. However, the actual hydrogen concentration that causes brittle fracture is unknown. In this study, slow strain rate tensile tests combined with finite element simulations (FESs) were used to study the influence of stress variation and initial hydrogen content C₀ (0.91, 1.70, 2.90, and 3.41 ppm) on the hydrogen redistribution and fracture behavior of smooth tensile specimens of Q960E steel for the first time. Furthermore, the actual threshold hydrogen content for hydrogen-delayed cracking was also obtained. Results showed that the presence of hydrogen significantly increases the elongation loss but has a minimal effect on strength loss. The occurrence of brittle cracking depends on the duration and the quantity of accumulated hydrogen. Brittle fracture occurs only at low strain rates under low C₀ of 0.91 and 1.70 ppm. However, a high strain rate can result in brittle fracture at high C₀ of 2.90 and 3.41 ppm. FES and fracture behavior indicate that the critical hydrogen content that causes brittle fracture is 1.8 ppm. If the C₀ is less than 1.8 ppm, brittle fracture is also observed at the center of the specimen by stress-induced hydrogen diffusion to achieve this critical value at low strain rate. A logarithmic relationship is observed between C₀ and the brittle zone size with a constant strain rate.

维修过程中材料中氢的吸收和积累是氢脆的主要前提。但是，导致脆性断裂的实际氢浓度是未知的。在这项研究中，慢应变速率拉伸试验与有限元模拟（FESs）相结合，用于研究应力变化和初始氢含量C _{0的影响。}（0.91、1.70、2.90和3.41 ppm）首次对Q960E钢的光滑拉伸试样的氢再分布和断裂行为产生了影响。此外，还获得了用于氢延迟裂化的实际阈值氢含量。结果表明，氢的存在显着增加了伸长率损失，但对强度损失的影响最小。脆性裂纹的发生取决于氢的持续时间和氢的数量。脆性断裂仅在0.91和1.70 ppm的低C ₀下以低应变速率发生。但是，高应变速率会导致在2.90和3.41 ppm的高C ₀下脆性断裂。FES和断裂行为表明，导致脆性断裂的临界氢含量为1.8 ppm。如果C ₀小于1.8ppm，由于应力引起的氢扩散，在试样中心也观察到脆性断裂，从而在低应变速率下达到该临界值。在恒定应变速率下，在C ₀和脆性区域尺寸之间观察到对数关系。