| 摘要 |
Provided are a steel material and a hydrogen container that achieves a lower fatigue crack propagation rate in a high-pressure hydrogen atmosphere than steels used in the related art, a method for producing the steel material, and a method for producing the hydrogen container. The steel material includes: a composition containing, by mass, C: 0.05% to 0.60%, Si: 0.01% to 2.0%, Mn: 0.3% to 3.0%, P: 0.001% to 0.040%, S: 0.0001% to 0.010%, N: 0.0001% to 0.0060%, Al: 0.01% to 1.5%, one or more elements selected from Ti: 0.01% to 0.20%, Nb: 0.01% to 0.20%, and V: 0.01% or more and less than 0.05%, and one or more elements selected from B: 0.0001% to 0.01%, Mo: 0.005% to 2.0%, and Cr: 0.005% to 3.0%, with the balance being Fe and inevitable impurities; and a steel microstructure that includes 95% or more of tempered martensite on a volume fraction basis, that includes a precipitate having a diameter of 100 nm or less and including one or more elements selected from Ti, Nb, and V and one or more elements selected from carbon and nitrogen at a density of 50 particles/µm 2 or more, and that includes prior austenite having a grain diameter of 3 µm or more. |
