Jfe Steel Corporation

Kabushiki Kaisha Kobe Seiko Sho

Shuichi Sakaguchi

Mitsuhiro Okatsu

Fumimaru Kawabata

Shigeki Nishiyama

Naoya Hayakawa

Keito Ishizaki

Makoto Ota

Kaoru Nagatani

Tokihiko Kataoka

A high-strength steel pipe has a tensile strength of 800 MPa or more and includes a weld metal having high cold-cracking resistance and high low-temperature toughness, wherein the weld metal contains C: 0.04% to 0.09% by mass, Si: 0.32% to 0.50% by mass, Mn: 1.4% to 2.0% by mass, Cu: less than 0.5% by mass, Ni: more than 0.9% by mass but not more than 4.2% by mass, Mo: 0.4% to 1.5% by mass, Cr: less than 0.5% by mass, V: less than 0.2% by mass, and the remainder of Fe and incidental impurities, and CS values calculated from the weld metal components using the equation CS=5.1+1.4[Mo]&#x2212;[Ni]&#x2212;[Mn]&#x2212;36.3[C] are equal to zero or more at both an internal surface and an external surface.

High-strength welded steel pipe including weld metal having high cold-cracking resistance and method for manufacturing the same

A steel wire for MAG welding in DC-electrode negative contains about 0.20% by mass or less of C, about 0.25% to about 2.5% by mass of Si, about 0.45% to about 3.5% by mass of Mn, about 0.005% to about 0.040% by mass of rare-earth elements, about 0.05% by mass or less of P, about 0.05% by mass or less of S, and the balance being Fe and incidental impurities. A method for MAG welding in DC-electrode negative for welding steel sheets having a thickness of about 0.2 to about 4.5 mm using the steel wire is also disclosed.

Steel wire for MAG welding and MAG welding method using the same

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Tokyo, Japan

Shuichi Sakaguchi