Invention Application
US20140318672A1 HIGH STRENGTH HOT ROLLED STEEL SHEET FOR LINE PIPE USE EXCELLENT IN LOW TEMPERATURE TOUGHNESS AND DUCTILE FRACTURE ARREST PERFORMANCE AND METHOD OF PRODUCTION OF SAME 审中-公开
用于线管的高强度热轧钢板在低温韧性和撕裂性能方面的应用性能及其生产方法

  • Patent Title: HIGH STRENGTH HOT ROLLED STEEL SHEET FOR LINE PIPE USE EXCELLENT IN LOW TEMPERATURE TOUGHNESS AND DUCTILE FRACTURE ARREST PERFORMANCE AND METHOD OF PRODUCTION OF SAME
  • Patent Title (中): 用于线管的高强度热轧钢板在低温韧性和撕裂性能方面的应用性能及其生产方法
  • Application No.: US14329295
    Application Date: 2014-07-11
  • Publication No.: US20140318672A1
    Publication Date: 2014-10-30
  • Inventor: Tatsuo YokoiHiroshi AbeOsamu Yoshida
  • Applicant: Nippon Steel & Sumitomo Metal Corporation
  • Applicant Address: JP Tokyo
  • Assignee: Nippon Steel Corporation
  • Current Assignee: Nippon Steel Corporation
  • Current Assignee Address: JP Tokyo
  • Priority: JP2008-137195 20080526; JP2009-077146 20090326
  • Main IPC: C21D8/02
  • IPC: C21D8/02
HIGH STRENGTH HOT ROLLED STEEL SHEET FOR LINE PIPE USE EXCELLENT IN LOW TEMPERATURE TOUGHNESS AND DUCTILE FRACTURE ARREST PERFORMANCE AND METHOD OF PRODUCTION OF SAME
Abstract:
The present invention has as its object the provision of hot rolled steel sheet (hot coil) for line pipe use in which API5L-X80 standard or better high strength and low temperature toughness and ductile fracture arrest performance are achieved and a method of production of the same.For this purpose, the hot rolled steel sheet of the present invention comprises C, Si, Mn, Al, N, Nb, Ti, Ca, V, Mo, Cr, Cu, and Ni in predetermined ranges and a balance of Fe and unavoidable impurities, in which the microstructure is a continuously cooled transformed structure, in which continuously cooled transformed structure, precipitates containing Nb have an average size of 1 to 3 nm and are included dispersed at an average density of 3 to 30×1022/m3, granular bainitic ferrite and/or quasi-polygonal ferrite are included in 50% or more in terms of fraction, furthermore, precipitates containing Ti nitrides are included, and they have an average circle equivalent diameter of 0.1 to 3 μm and include complex oxides including Ca, Ti, and Al in 50% or more in terms of number.
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