STEEL MATERIAL, HYDROGEN CONTAINER, METHOD FOR PROUCING THE STEEL MATERIAL, AND METHOD FOR PRODCUING THE HYDROGEN CONTAINER

• Main Authors: TAKAGI, SHUSAKU, NAGAO, AKIHIDE
• Format: Patent
• Language: English; French
• Published: 02.10.2014
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

Provided are: a steel material for which fatigue crack propagation rate in a high pressure hydrogen environment can be reduced more than with prior steel; a hydrogen container; and manufacturing methods therefor. A steel material with a steel structure having a component composition containing, in mass%, C: 0.05-0.60%, Si: 0.01-2.0%, Mn: 0.3-3.0%, P: 0.001-0.040%, S: 0.0001-0.010%, N: 0.0001-0.0060%, and Al: 0.01-1.5%, also containing at least one from among Ti: 0.01-0.20%, Nb: 0.01-0.20%, and V: 0.01% to less than 0.05%, and containing at least one from among B: 0.0001-0.01%, Mo: 0.005-2.0% and Cr: 0.005-3.0%, the remainder being Fe and unavoidable impurities. In the steel structure, at least 95% by volume fraction is tempered martensite, the density of deposits with a diameter of not more than 100 nm and having at least one of Ti, Nb and V and at least one of carbon and nitrogen is at least 50 grains/µm2, and the prior austenite grain diameter is at least 3 µm.