Effects of hydrogen on the mechanical response of X80 pipeline steel subject to high strain rate tensile tests

• Published in: Fatigue & fracture of engineering materials & structures Vol. 43; no. 4; pp. 684 - 697
• Main Authors: Zheng, Yuanyuan, Zhang, Lin, Shi, Qiaoying, Zhou, Chengshuang, Zheng, Jinyang
• Format: Journal Article
• Language: English
• Published: Oxford Wiley Subscription Services, Inc 01.04.2020
• Subjects: Annealing; Degradation; Diffusion rate; Dislocation mobility; Dislocation pinning; High strain rate; High strength low alloy steels; high‐strain rate tensile test; Hydrogen; Hydrogen charging; Hydrogen embrittlement; hydrogen permeation; iron alloys; Mechanical analysis; Plastic properties; plasticity degradation; Structural steels; Tensile tests
• ISSN: 8756-758X; 1460-2695
• DOI: 10.1111/ffe.13151

Hydrogen‐induced degradation of X80 pipeline steel was investigated through a high strain rate tensile test (2 × 10−4/s) with interposed unloading, reloading, aging at 30°C, or annealing at 200°C with or without hydrogen charging. The results indicated that plasticity degradation does not occur in the hydrogen‐precharged specimens; however, hydrogen embrittlement occurs in the reloading stage when the specimens are charged with hydrogen in the unloading stage after applying a prestrain. Interposed aging at 30°C or annealing at 200°C can also increase the degradation. It indicates that the hydrogen traps caused by the strain along with hydrogen charging are the major source of dislocations. The formation of a hydrogen atmosphere around mobile dislocations, which is related to the rates of hydrogen diffusion and dislocation movement, plays an important role in the degradation process. Both pinning and depinning of dislocations affect plasticity degradation.