Hot-rolled steel sheet for high-strength electric-resistance welded pipe having sour-gas resistance and exellent weld toughness, and method for manufacturing the same
First Claim
1. A hot-rolled steel sheet for a high-strength electric-resistance welded pipe having sour-gas resistance and excellent weld toughness, comprising:
- about 0.02% to about 0.06% C;
about 0.05% to about 0.50% Si;
about 0.5% to about 1.5% Mn;
about 0.010% or less P;
about 0.0010% or less S;
about 0.01% to about 0.10% Al;
about 0.01% to about 0.10% Nb;
about 0.001% to about 0.025% Ti;
about 0.001% to about 0.005% Ca;
about 0.003% or less O;
about 0.005% or less N, and at least one element selected from the group consisting of about 0.01% to about 0.10% V;
about 0.01% to about 0.50% Cu;
about 0.01% to about 0.50% Ni; and
about 0.01% to about 0.50% Mo on the basis of mass, wherein C, Si, Mn, Cu, Ni, Mo, and V satisfy Px given by Relationship 1;
Px=(C)+(Si)/30+((Mn)+(Cu))/20+(Ni)/60+(Mo)/7+(V)/10≦
0.17
(1)where (M) indicates the content by mass percent of an element M;
Ca, O, and S satisfy Py given by Relationship 2;
Py={(Ca)−
(130×
(Ca)+0.18)×
(O)}/(1.25×
(S)) 1.2≦
Py≦
3.6
(2)where (M) indicates the content by mass percent of an element M;
the balance is Fe and incidental impurities; and
the microstructure of the steel sheet is composed of about 95% by volume or more bainitic ferrite.
1 Assignment
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Accused Products
Abstract
A hot-rolled steel sheet for high-strength ERW pipes contains about 0.02% to about 0.06% C; about 0.05% to about 0.50% Si; about 0.5% to about 1.5% Mn; about 0.010% or less P; about 0.0010% or less S; about 0.01% to about 0.10% Al; about 0.01% to about 0.10% Nb; about 0.001% to about 0.025% Ti; about 0.001% to about 0.005% Ca; about 0.003% or less 0; and about 0.005% or less N, and at least one element selected from the group consisting of about 0.01% to about 0.10% V; about 0.01% to about 0.50% Cu; about 0.01% to about 0.50% Ni; and about 0.01% to about 0.50% Mo on the basis of mass. The group of C, Si, Mn, Cu, Ni, Mo, and V and the group of Ca, 0, and S satisfy specific relationships, and the microstructure of the steel sheet is composed of about 95% by volume or more bainitic ferrite.
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Citations
10 Claims
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1. A hot-rolled steel sheet for a high-strength electric-resistance welded pipe having sour-gas resistance and excellent weld toughness, comprising:
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about 0.02% to about 0.06% C;
about 0.05% to about 0.50% Si;
about 0.5% to about 1.5% Mn;
about 0.010% or less P;
about 0.0010% or less S;
about 0.01% to about 0.10% Al;
about 0.01% to about 0.10% Nb;
about 0.001% to about 0.025% Ti;
about 0.001% to about 0.005% Ca;
about 0.003% or less O;
about 0.005% or less N, and at least one element selected from the group consisting of about 0.01% to about 0.10% V;
about 0.01% to about 0.50% Cu;
about 0.01% to about 0.50% Ni; and
about 0.01% to about 0.50% Mo on the basis of mass, whereinC, Si, Mn, Cu, Ni, Mo, and V satisfy Px given by Relationship 1;
Px=(C)+(Si)/30+((Mn)+(Cu))/20+(Ni)/60+(Mo)/7+(V)/10≦
0.17
(1)where (M) indicates the content by mass percent of an element M;
Ca, O, and S satisfy Py given by Relationship 2;
Py={(Ca)−
(130×
(Ca)+0.18)×
(O)}/(1.25×
(S)) 1.2≦
Py≦
3.6
(2)where (M) indicates the content by mass percent of an element M;
the balance is Fe and incidental impurities; and
the microstructure of the steel sheet is composed of about 95% by volume or more bainitic ferrite. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification
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- Resources
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Current AssigneeJFE Steel Corporation (JFE Holdings Incorporated)
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Original AssigneeJFE Steel Corporation (JFE Holdings Incorporated)
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InventorsKobayashi, Takashi, Kami, Chikara, Kawamura, Shuji, Nakata, Hiroshi, Inazumi, Toru
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Granted Patent
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Time in Patent OfficeDays
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Field of Search
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US Class Current148/593
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CPC Class CodesC21D 8/0226 Hot rollingC22C 38/02 containing siliconC22C 38/04 containing manganeseC22C 38/08 containing nickel C22C38/10...C22C 38/12 containing tungsten, tantal...C22C 38/16 containing copper
