Nippon Steel Corporation

Japan Casting & Forging Corporation

Kawasaki Steel Corporation

Japan As Represented by Director General, Technical Research and

Seinosuke Yano

Yoshihiro Okamura

Takashi Harabuchi

Ryota Yamaba

Syuzo Ueda

Junichi Kobayashi

Naoki Saito

Hirohide Muraoka

Yasuhiko Yamashita

Katsuo Kaku

Ko Moriyama

Kimio Nagata

Seimei Karino

Yasuho Imai

Hisayoshi Yatoh

Yoichiro Tobe

Hidetaka Chiba

Hiroshi Mochiki

Yoshikazu Nakano

Koh Moriyama

Cold rolled steel having excellent machinability and production thereof

High strength hot rolled steel plates and sheets excellent in uniform

A method of high tension steel having superior weldability and low temperature toughness, comprises the steps of preparing a steel billet having a composition consisting, by weight, of 0.02 to 0.05% C, 0.02 to 0.5% Si, 0.4 to 1.5% Mn, 0.5 to 4.0% Ni, 0.20 to 1.5% Mo, 0.005 to 0.03% Ti, 0.01 to 0.08% Al, not more than 0.0002% B, 0.5 to 2.0% Cu, not more than 0.01% N, and the balance Fe and incidental impurities; heating said steel billet to a temperature of 900.degree. C. to 1000.degree. C.; hot-rolling the heated steel billet first at a rolling reduction of 30 to 70% in a temperature range in which austenite recrystallizes and then at a rolling reduction of 20 to 60% in another temperature range in which austenite does not recrystallize; hardening the hot-rolled billet by water-cooling from a temperature not lower than the Ar.sub.3 transformation point and terminating the cooling at a temperature not higher than 250.degree. C.; and tempering the hardened billet at a temperature which is not higher than the Ac.sub.1 transformation point.

Method of producing high tension steel superior in weldability and

A process for producing steel possessing a high level of toughness and strength free of anisotropy and having good resistance to stress corrosion cracking in seawater conditions comprises the steps of:

Process for producing high toughness, high strength steel having

A process for producing a high toughness, high strength steel having excellent resistance to stress corrosion cracking including the steps of: preparing a steel slab including 0.02 to 0.10 wt % of C, 0.50 wt % or less Si, 0.4 to 1.5 wt % Mn, 1.0 to 7.5 wt % Ni, more than 1.0 wt % up to 1.5 wt % Mo, 0.80 wt % or less Cr, 0.01 to 0.08 wt % sol. Al, and the balance of Fe and unavoidable impurities; heating the steel slab to a temperature of from 1000.degree. C. to 1250.degree. C.; hot rolling the heated steel slab at a finishing nip temperature of from 700.degree. C. to 880.degree. C., at a total reduction rate of 40% or more effected at the finishing nip temperature or lower, and at a finishing temperature of 650.degree. C. or higher, to provide a steel plate; then quenching the steel plate by initiating water cooling at a temperature of the A.sub.r3 point thereof or higher and by terminating the water cooling at a temperature of 150.degree. C. or lower; and tempering the quenched steel plate at a temperature of the A.sub.c1 point thereof or lower.

A high toughness, ultra high-strength steel having an excellent stress corrosion cracking resistance with a yield stress of not less than 110 kgf/mm.sup.2, which comprises 0.06-0.20 wt % of C, not more than 0.35 wt % of Si, 0.05-1.0 wt % of Mn, 8-11 wt % of Ni, 0.2-2.5 wt % of Cr, 0.7-2.5 wt % of Mo, 0.05-0.2 wt % of V, 0.01-0.08 wt % of Al, not more than 0.005 wt % of N, not more than 0.003 wt % of O, provided that the value of Al (%).times.N (%).times.10.sup.4 is not more than 1.5, and the balance being substantially Fe and inevitable impurities.

High toughness, ultra-high strength steel having an excellent stress

A process for producing a Ni-steel with high crack-arresting capability is disclosed. The process comprises the steps of:

Process for producing nickel steels with high crack-arresting capability

Growing community of inventors

Kitakyusyu, Japan

Seinosuke Yano