Steel and component of structural equipment for use in a hydrogen gas environment, and a method for the manufacture thereof

Abstract

A steel which does not suffer from hydrogen embrittlement contains 0.3-30% of Cr as the base material, and has an oxide film having a thickness of 100 nm or more formed on its surface. The oxide film contains at least two elements selected among Fe, Cr and Al in the form of oxides, respectively in an amount of 5 atom % or more. The oxide film is formed through single-step or two-step heating wherein the steel is heated in the atmosphere at 600-900° C. for not less than 3 minutes but not more than 2 hours if necessary, and then heated in a hydrogen atmosphere at 700-1200° C. for not less than 3 minutes but not more than 2 hours while controlling the water vapor partial pressure within the range from 10 −8 to 10 −1 MPa. The steel is adapted for use in hydrogen gas environments, such as a container or other hardware.

1 . A steel material for use in a hydrogen environment, which contains, in mass %, 0.3-30% of Cr and having on its surface an oxide film for preventing hydrogen penetration containing at least 5 atom % of Fe and at least 5 atom % of Cr and having a thickness of at least 100 nm.  
   
   
       2 . A steel material for use in a hydrogen environment, which contains, in mass %, 0.3-30% of Cr and having on its surface an oxide film for preventing hydrogen penetration containing at least 30 atom % of Fe and at least 30 atom % of Cr and having a thickness of at least 100 nm.  
   
   
       3 . A steel material containing, in mass %, 12-30% of Cr and 0.005-6% of Al and having on its surface an oxide film for preventing hydrogen penetration containing Fe and Al, or Cr and Al, or Fe and Cr and Al in the amounts of at least 5 atom % of Fe, at least 5 atom % of Cr, and at least 5 atom % of Al and having a thickness of at least 100 nm.  
   
   
       4 . A steel material containing, in mass %, 12-30% of Cr and 1-6% of Al and having on its surface an oxide film for preventing hydrogen penetration containing Fe and Al, or Cr and Al, or Fe and Cr and Al in the amounts of at least 5 atom % of Fe, at least 5 atom % of Cr, and at least 50 atom % of Al and having a thickness of at least 100 nm.  
   
   
       5 . A steel material having a metal layer comprising at least one of Al, Cu, and Zn atop an oxide film as set forth in  claim 1 .  
   
   
       6 . A component for structural equipment for high pressure hydrogen gas made from a steel as set forth in  claim 1 .  
   
   
       7 . A method of manufacturing a steel as set forth in  claim 3  characterized by heating a steel containing 12-30% of Cr in air at a temperature of 600-900° C. for at least 3 minutes and at most 2 hours and then heating it in a hydrogen atmosphere containing steam at a partial pressure controlled to 10 −8  to 10 −1  MPa at a temperature of at least 700° C. and at most 1200° C. for at least 3 minutes and at most 2 hours.  
   
   
       8 . A method of manufacturing a steel as set forth in  claim 3  characterized by heating a steel containing 12-30% of Cr and 3-6% of Al in a hydrogen atmosphere containing steam at a partial pressure controlled to 10 −8  to 10 −1  MPa at a temperature of at least 700° C. and at most 1200° C. for at least 3 minutes and at most 2 hours.  
   
   
       9 . A steel material having a metal layer comprising at least one of Al, Cu, and Zn atop an oxide film as set forth in  claim 2 .  
   
   
       10 . A steel material having a metal layer comprising at least one of Al, Cu, and Zn atop an oxide film as set forth in  claim 3 .  
   
   
       11 . A steel material having a metal layer comprising at least one of Al, Cu, and Zn atop an oxide film as set forth in  claim 4 .  
   
   
       12 . A component for structural equipment for high pressure hydrogen gas made from a steel as set forth in  claim 2 .  
   
   
       13 . A component for structural equipment for high pressure hydrogen gas made from a steel as set forth in  claim 3 .  
   
   
       14 . A component for structural equipment for high pressure hydrogen gas made from a steel as set forth in  claim 4 .  
   
   
       15 . A component for structural equipment for high pressure hydrogen gas made from a steel as set forth in  claim 5 .  
   
   
       16 . A method of manufacturing a steel as set forth in  claim 4  characterized by heating a steel containing 12-30% of Cr in air at a temperature of 600-900° C. for at least 3 minutes and at most 2 hours and then heating it in a hydrogen atmosphere containing steam at a partial pressure controlled to 10 −8  to 10 −1  MPa at a temperature of at least 700° C. and at most 1200° C. for at least 3 minutes and at most 2 hours.  
   
   
       17 . A method of manufacturing a steel as set forth in  claim 4  characterized by heating a steel containing 12-30% of Cr and 3-6% of Al in a hydrogen atmosphere containing steam at a partial pressure controlled to 10 −8  to 10 −1  MPa at a temperature of at least 700° C. and at most 1200° C. for at least 3 minutes and at most 2 hours.