Abstract: A hydrogen pressure vessel capable of preventing hydrogen-induced cracking of a cylinder is provided. In a hydrogen pressure vessel according to one embodiment, a gap part (G) in which an inner peripheral surface of a cylinder (10) is spaced apart from an outer peripheral surface of a lid (20) is provided between a female thread part (10a) of the cylinder (10) into which the lid (20) is screwed, and a resin seal member (30), and the cylinder (10) includes a first through hole (41) for discharging gas in the gap part (G) into a relief pipe (51) and a second through hole (42) for introducing gas containing oxygen into the gap part (G) formed therein.

Abstract: The present invention provides a pressure vessel for hydrogen in which the development of cracking in the pressure vessel for hydrogen can be effectively inhibited and that is excellent in terms of safety, reliability, and durability. The present invention pertains to a pressure vessel for hydrogen in which a plastic region is present on the inner face side of a hydrogen pressure vessel main body, an elastic region is present on the outer face side, and compressive residual stress is generated on the inner face, wherein preferably: the equivalent plastic strain remaining on the inner surface of the hydrogen pressure vessel main body is 1% or below; the plastic region on the inner face side measures 50% or less of the wall thickness in the radial direction of the hydrogen pressure vessel main body; and the steel used has a tensile strength of at least 725 MPa.

Abstract: A melt of a hydrogen storage alloy having an arbitrary composition is cooled gradually at a cooling rate of 5° C./min or less and solidified. Alternatively an alloy having an arbitrary composition, after heating to a temperature equal to or more than a melting point thereof, is cooled gradually at a cooling rate of 5° C./min or less and solidified. Thereby a homogeneous alloy reduced in segregation, precipitates, or inclusions is obtained. The homogeneous alloy is excellent in the hydrogen storage amount, in the plateau property and in durability.

Abstract: The invention intends to provide a hydrogen storage alloy that can absorb and release hydrogen effectively at room temperature and shows excellent hydrogen storage amount and effective hydrogen transfer amount and furthermore shows excellent endurance. A pulverized hydrogen storage alloy powder is heated at 600° C. or more and 1200° C. or less for 10 min to 30 hr to apply strain relief annealing. A particle diameter of the hydrogen storage alloy powder is desirably 10 ?m or less and the hydrogen storage alloy is desirably mainly composed of a BCC phase. Since the initial strain ahead of the hydrogenation is removed, a solid solution region of hydrogen is largely reduced and an initial hydrogen storage amount and an effective hydrogen transfer amount are increased.

Abstract: A melt of a hydrogen storage alloy having an arbitrary composition is cooled gradually at a cooling rate of 5° C./min or less and solidified. Alternatively an alloy having an arbitrary composition, after heating to a temperature equal to or more than a melting point thereof, is cooled gradually at a cooling rate of 5° C./min or less and solidified. Thereby a homogeneous alloy reduced in segregation, precipitates, or inclusions is obtained. The homogeneous alloy is excellent in the hydrogen storage amount, in the plateau property and in durability.

Abstract: A melt of a hydrogen storage alloy having an arbitrary composition is cooled gradually at a cooling rate of 5° C./min or less and solidified. Alternatively an alloy having an arbitrary composition, after heating to a temperature equal to or more than a melting point thereof, is cooled gradually at a cooling rate of 5° C./min or less and solidified. Thereby a homogeneous alloy reduced in segregation, precipitates, or inclusions is obtained. The homogeneous alloy is excellent in the hydrogen storage amount, in the plateau property and in durability.

Abstract: A melt of a hydrogen storage alloy having an arbitrary composition is cooled gradually at a cooling rate of 5° C./min or less and solidified, alternatively an alloy having an arbitrary composition, after heating to a temperature equal to or more than a melting point thereof, is cooled gradually at a cooling rate of 5° C./min or less and solidified, and thereby a homogeneous alloy reduced in the segregation, precipitates or inclusions is obtained. An effective hydrogen storage amount, the plateau property and the durability more excellent than ever can be obtained.