公开(公告)号：EP3246418A4

公开(公告)日：2017-11-22

申请号：EP15877751

申请日：2015-12-03

Applicant: JFE STEEL CORP

Inventor： FUJIMURA KAZUKI ,  ISHIGURO YASUHIDE ,  GOTO SEIGO

IPC: C21D8/10 ,  C21D6/00 ,  C21D9/08 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/40 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58

CPC classification number: C21D9/085 ,  C21D1/25 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/10 ,  C21D8/105 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/40 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58

Abstract: Provided are a method of manufacturing a seamless stainless steel pipe for Oil Country Tubular Goods with excellent hot workability, by which a seamless stainless steel pipe for Oil Country Tubular Goods having high strength of 110ksi (=758MPa) or more in terms of yield strength, high toughness of 40J or more in terms of absorption energy vE -10 in a Charpy impact test at a test temperature of -10°C and excellent corrosion resistance can be acquired, and a seamless stainless steel pipe for Oil Country Tubular Goods acquired by the method. A billet which has the composition containing predetermined components and in which the contents of C, Si, Mn, Cr, Mo, Ni, N, W, Cu satisfy the predetermined relationship is heated, hot working is applied to the billet thus forming a seamless steel pipe, the seamless steel pipe is cooled to a room temperature at a cooling rate of air cooling or more, thereafter, quenching is performed by heating the seamless steel pipe to a temperature of 850°C or above and, subsequently, by cooling the seamless steel pipe to a temperature of 100 °C or below at a cooling rate of air cooling or more and, subsequently, tempering is applied to the seamless steel pipe at a temperature of 700°C or below for a predetermined holding time.