Austenitic stainless steel and process for removing hydrogen therefrom

Abstract

By focusing on the non-diffusible hydrogen that causes hydrogen embrittlement of austenitic stainless steel, the present invention provides an austenitic stainless steel in which the non-diffusible hydrogen is removed by maintaining the austenitic stainless steel in a vacuum of 0.2 Pa or less and heating at a heating temperature of 200° C. to 500° C. for 460 hours or less to remove the hydrogen (H) contained therein to a level of 0.00007 mass % (0.7 mass ppm) or less.

1 . An austenitic stainless steel having an austenitic phase in which a crystalline structure is a face centered cubic lattice structure,
 wherein diffusible hydrogen and non-diffusible hydrogen, which are cause of hydrogen embrittlement in the austenitic stainless steel, are removed therefrom such that the hydrogen (H) contained in the austenitic stainless steel is removed to a level of 0.00007 mass % (0.7 mass ppm) or less.   
   
   
       2 . The austenitic stainless steel according to  claim 1 ,
 wherein the diffusible hydrogen and non-diffusible hydrogen are removed therefrom such that the hydrogen (H) is removed to a level of 0.00004 mass % (0.4 mass ppm) or less.   
   
   
       3 . The austenitic stainless steel according to  claim 2 ,
 wherein the diffusible hydrogen and non-diffusible hydrogen are removed therefrom such that the hydrogen (H) is removed to a level of 0.00001 mass % (0.1 mass ppm) or less.   
   
   
       4 . The austenitic stainless steel according to any one of  claims 1  to  3 ,
 wherein the austenitic stainless steel is heat-treated at a heating temperature of 200° C. or higher to remove the diffusible and non-diffusible hydrogen therefrom.   
   
   
       5 . The austenitic stainless steel according to  claim 4 ,
 wherein the heating temperature is a temperature from 200° C. to 500° C.