Hydrogen Embrittlement and Lattice Defect Formation Enhanced by Hydrogen and Strain of High-Strength Low-Alloy Steel

摘要

The hydrogen embrittlement susceptibility of Cr-Mo steel, a kind of high-strength low-alloy steel, was evaluated based on the difference in ductility loss with and without hydrogen charging at various strain rates. Hydrogen contents were measured by hydrogen thermal desorption analysis as a tracer of lattice defects. The results revealed that the amount of lattice defects was enhanced by hydrogen charging and straining at a low strain rate. The enhanced lattice defects corresponded to vacancies, since they were reduced by annealing at 200℃. In addition, the critical amount of lattice defects to fracture with hydrogen was almost equal to that without hydrogen at a low strain rate. Therefore, the role of hydrogen in embrittlement is to enhance vacancy formation toward the critical amount of defects inducing fracture in spite of a lower strain level.