Austenitic stainless steel for hydrogen gas and method for its manufacture

Abstract

An austenitic stainless steel for use in a hydrogen gas atmosphere comprises, in mass %, C: 0.10% or less, Si: 1.0% or less, Mn: 0.01 to 30%, P: 0.040% or less, S: 0.01% or less, Cr: 15 to 30%, Ni: 5.0 to 30%, Al: 0.10% or less, N: 0.001 to 0.30 % with the balance Fe and inevitable impurities. An X-ray (111) integration intensity of a cross section along the direction rectangular to the working direction is five times that in a random direction or less, and the X-ray integration intensity ratio of a cross section along the working direction satisfies I(220) / I(111)≦10. The high strength steel can also contain one or more of the groups of Mo and W; V, Nb, Ta, Ti, Zr and Hf; B; Cu and Co; Mg, Ca, La, Ce, Y, Sm, Pr and Nd.

Description

TECHNICAL FIELD [0001] This invention relates to a stainless steel for use in a hydrogen gas environment which has excellent mechanical properties (strength and ductility) and corrosion resistance and to a method for its manufacture. In addition, the present invention relates to equipment used in a hydrogen gas environment such as piping, gas cylinders, and valves for hydrogen gas made from such a stainless steel. [0002] A stainless steel according to the present invention is particularly suitable as a steel for structural equipment which is exposed to a high pressure hydrogen gas environment in fuel cell automobiles and hydrogen gas stations, and particularly for piping, gas cylinders, and valves. BACKGROUND ART [0003] As is well known, fuel cell automobiles obtain electric power using hydrogen and oxygen as fuels. They have attracted attention as the next generation of clean automobiles which do not discharge carbon dioxide (CO2) or harmful substances such as nitrogen oxides (NOx)...

AI Technical Summary

Benefits of technology

[0018] The object of the present invention is to provide an austenitic stainless steel which has excellent mechanical properties and corrosion resistance and which can be used in a hydrogen gas environment such as one containing high pressure hydrogen gas at 70 MPa or above and to provide a method for its manufacture.

[0044] In this manner, according to the present invention, it is possible to obatin a high strength austenitic stainless steel which does not undergo hydrogen embrittlement even in a high pressure hydrogen gas environment such as 70 MPa or above and which does not have anisotropy of mechanical properties. It exhibits particularly excellent properties in vessels, piping, valves, and the like which are used in a hydrogen gas station or a fuel cell automobile and are exposed to a high pressure hydrogen gas environment.

Problems solved by technology

In actual practice, elongation of at least about 30% is desirable, but when the degree of cold working is large, a decrease in elongation becomes a problem.

Accordingly, in light of safety in handling high pressure hydrogen gas, it has been thought that cold working could not be employed to obtain a high strength.

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