公开(公告)号：EP3263732A4

公开(公告)日：2018-07-11

申请号：EP16755632

申请日：2016-02-25

申请人： NAT INSTITUTE FOR MATERIALS SCIENCE

发明人： KIMURA KAZUHIRO ,  SAWADA KOTA ,  KUSHIMA HIDEAKI ,  TANIUCHI YASUSHI ,  OHBA TOSHIO

IPC分类号： C22C38/00 ,  C21D6/00 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/32

CPC分类号： C21D6/008 ,  C21D1/28 ,  C21D6/00 ,  C21D6/002 ,  C21D6/004 ,  C21D6/005 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/32

摘要： The invention provides a ferritic heat-resistant steel whose creep rupture ductility in a long-term region is improved without detrimental to creep strengths. The ferritic heat-resistant steel has a chemical composition comprising, in % by mass, C: 0.03 to 0.15, Si: 0 to 0.8, Mn: 0.1 to 0.8, Cr: 8.0 to 11.5, Mo: 0.2 to 1.5, (W: 0.4 to 3.0), V: 0.1 to 0.4, Nb: 0.02 to 0.12 N: 0.02 to 0.10 with the balance of iron and inevitable impurities. This steel has a tempered martensite microstructure, and has an improved creep rupture ductility even when there is a load within the elastic limits at temperatures at which the ferritic heat-resistant steel is used, because internal strain or internal stress induced by martensitic transformation is relaxed or released by an intermediate tempering heat treatment in a two-phase state temperature in which a portion of an austenitic phase undergoes martensitic transformation.