Jfe Steel Corporation

Exxonmobil Upstream Research Company

Shinichi Kakihara

Makoto Suzuki

Nobuyuki Ishikawa

Shusaku Ota

Narasimha-Rao Venkata Bangaru

Jayoung Koo

Shigeru Endo

Hideyuki Kimura

Mitsuhiro Okatsu

Hyun-Woo Jin

Douglas Paul Fairchild

Adnan Ozekcin

Raghavan Ayer

Nobuo Shikanai

Moriyasu Nagae

Tomohiro Matsushima

Yutaka Awajiya

Danny Lee Beeson

James B LeBleu, Jr

Douglas S Hoyt

Ryo Nagao

Akiyoshi Tsuji

Yoshiaki Ota

Narasimha V Bangaru

Danny L Beeson

Hiroshi Awajiya

Disclosed is, as a high-strength steel plate of API X80 grade or higher with a thickness of 38 mm or more, a steel plate for structural pipes or tubes that exhibits excellent resistance to PWHT and excellent toughness at the heat-affected zone, particularly at the butting faces joined by welding, without addition of large amounts of alloying elements. The steel plate for structural pipes or tubes disclosed herein has a specific chemical composition, in which the steel plate has mechanical properties including: (a) a 0.5% yield strength of 555 MPa or more; (b) a tensile strength of 625 MPa or more; and (c) a Charpy absorption energy vEat &#x2212;10&#xb0; C. at its mid-thickness part of 250 J or more, and maintains the mechanical properties (a) to (c) even after subjection to heat treatment at 650&#xb0; C. for 2 hours.

Steel plate for structural pipes or tubes, method of producing steel plate for structural pipes or tubes, and structural pipes and tubes

A high strength/highstrength, high toughness steel sheet having tensile strength, Charpy impact absorption energy, and ductile fracture rate are equal to or greater than specified values comprises, in mass %, 0.03-0.08% of C, 0.01-0.50% of Si, 1.5-2.5% of Mn, 0.001-0.010% of P, 0.0030% or less of S, 0.01-0.08% of Al, 0.010-0.080% of Nb, 0.005-0.025% of Ti, 0.001-0.006% of N, at least one substance selected from among 0.01-1.00% of Cu, 0.01-1.00% of Ni, 0.01-1.00% of Cr, 0.01-1.00% of Mo, 0.01-0.10% of V, and 0.0005-0.0030% of B, and a remainder of Fe and unavoidable impurities. At a position at &#xbd; the sheet thickness, the area ratio of island-like martensite is less than 3%, the area ratio of bainite is 90% or more, and the average particle size of cementite within the bainite is 0.5 &#x3bc;m or less.

High-strength, high-toughness steel plate, and method for producing the same

A steel composition and method from making a dual phase steel therefrom. The dual phase steel may have carbon of about 0.05% by weight to about 0.12 wt %; niobium of about 0.005 wt % to about 0.03 wt %; titanium of about 0.005 wt % to about 0.02 wt %; nitrogen of about 0.001 wt % to about 0.01 wt %; silicon of about 0.01 wt % to about 0.5 wt %; manganese of about 0.5 wt % to about 2.0 wt %; and a total of molybdenum, chromium, vanadium and copper less than about 0.15 wt %. The steel may have a first phase consisting of ferrite and a second phase having one or more of carbide, pearlite, martensite, lower bainite, granular bainite, upper bainite, and degenerate upper bainite. A solute carbon content in the first phase may be about 0.01 wt % or less.

Low yield ratio dual phase steel linepipe with superior strain aging resistance

A steel plate for line pipes containing, in terms of % by weight, C: 0.02 to 0.06%, Si: 0.5% or less, Mn: 0.8 to 1.6%, P: 0.008% or less, S: 0.0008% or less, Al: 0.08% or less, Nb: 0.005 to 0.035%, Ti: 0.005 to 0.025%, and Ca: 0.0005 to 0.0035%, and optionally contains one or more of Cu: 0.5% or less, Ni: 1% or less, Cr: 0.5% or less, Mo: 0.5% or less and V: 0.1% or less, and has a CP value of 0.95 or less represented by CP=4.46C(%)+2.37Mn(%)/6+{1.18Cr(%)+1.95Mo(%)+1.74V(%)}/5+{1.74Cu(%)+1.7Ni(%)}/15+22.36P(%), and a Ceq value of 0.30 or more represented by Ceq=C(%)+Mn(%)/6+{Cr(%)+Mo(%)+V(%)}/5 +{Cu(%)+Ni(%)}/15.

Steel plate and steel pipe for line pipes

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Tokyo, Japan

Shinichi Kakihara