Martensitic steel for line pipe having excellent corrosion resistance and weldability

US5985209A · kind A · utility

Assignee

• Kawasaki Steel Corporation · JP

Inventors

• Mitsuo Kimura · Yokohama, JP
• Yukio Miyata · Tondabayashi, JP
• Tomoya Koseki · Kurashiki, JP
• Takaaki Toyooka · Ebeye, US
• Fumio Murase · Ebeye, US

Key dates

• Filing date: Mar 21, 1997
• Grant date: Nov 16, 1999
• Expiry date: Mar 21, 2017

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C22C38/44
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A martensitic steel for a line pipe having excellent corrosion resistance and weldability is disclosed. The martensitic steel contains about: PA1 0.02 wt % or less of C, 0.50 wt % or less of Si, PA1 0.2 to 3.0 wt % of Mn, 10 to 14 wt % of Cr, PA1 0.2 to 7.0 wt % of Ni, 0.2 to 5.0 wt % of Mo, PA1 0.1 wt % or less of Al, 0.07 wt % or less of N, and PA1 the balance being Fe and incidental impurities; and these elements satisfy substantially the following equations: EQU (Cr %)+(Mo %)+0.1(N %)-3(C %).gtoreq.12.2, EQU (Cr %)+3.5(Mo %)+10(N %)+0.2(Ni %)-20(C %).gtoreq.14.5, and EQU 150(C %)+100(N %)-(Ni %)-(Mn %).ltoreq.4. The martensitic steel may further contain at least one element selected from the group consisting of about 2.0 wt % or less of Cu, about 0.15 wt % or less of Ti, about 0.15 wt % or less of Zr, about 0.15 wt % or less of Ta and PA1 about 0.006 wt % or less of Ca, and these elements satisfy substantially the following equations: EQU (Cr %)+(Mo %)+0.1(N %)+3(Cu %)-3(C %).gtoreq.12.2, EQU (Cr %)+3.5(Mo %)+10(N %)+0.2(Ni %)-20(C %).gtoreq.14.5, EQU 150(C %)+100(N %)-(Ni %)-(Mn %).ltoreq.4.