Nkk Corporation

Mitoshi Morimoto

Toshihiro Takamura

Yoshiichi Ishizawa

Fumihiro Nishimura

Tatsuo Maeda

Tetsuro Sugayoshi

Yuji Sugimoto

An electric-resistance-welded steel pipe with high strength consists essentially of 0.05 to 0.30 wt. % C, 0.6 to 2.0 wt. % Mn, 0.03 to 0.70 wt. % Si, and 0.01 to 0.05 wt. % Nb. The balance is Fe and inevitable impurities, the steel pipe having a martensitic phase ratio of 60 to 100% and having a tensile strength of 120 to 170 kgf/mm.sup.2.

Electric-resistance-welded steel pipe with high strength

An electric-resistance-welded steel pipe with high strength. The pipe consists essentially of (a) 0.05 to 0.30 wt. % C, (b) 0.6 to 2.0 wt. % Mn, (c) 0.03 to 0.70 wt. % Si, (d) (i) 0.5 wt. % or less Mo by itself or (ii) 0.5 wt. % or less Mo with 1.2 wt. % or less Cr or (iii) 0.5 wt. % or less Mo with 0.1 wt. % or less V or (iv) 0.1 wt. % or less V and (e) the balance being Fe and inevitable impurities. The steel pipe has a martensitic phase in an amount of 60 to 100% and has a tensile strength of 120 to 170 kgf/mm.sup.2. The steel pipe is useful as an impact bar for the inside of an automobile door.

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Kawasaki, Japan

Mitoshi Morimoto