Nkk Corporation

Jfe Steel Corporation

Seishi Tsuyama

Yoshihiro Hosoya

Kuninori Minakawa

Nobuyuki Ishikawa

Yasunobu Nagataki

Shigeru Endo

Tomoyoshi Okita

Akio Fujibayashi

Junji Shimamura

Masaya Morita

Yasuyuki Takada

Shinji Mitao

Hiromi Nakamura

Satoshi Kohira

Kazuo Omata

Isao Takahashi

Tetsuo Sakiyama

Akira Tagane

Shuji Kanetoh

Daijiro Koyanagi

Shusaku Ohta

Shuzi Kanetoh

A steel plate has a chemical composition containing, by mass %, C: 0.03% or more and 0.10% or less, Si: 0.05% or more and 0.50% or less, Mn: 1.00% or more and 2.00% or less, P: 0.015% or less, S: 0.005% or less, Mo: 0.20% or less (including 0%), Nb: 0.01% or more and 0.05% or less, and the balance being Fe and inevitable impurities, and, if desired, containing, by mass %, one or more of Al: 0.005% or more and 0.1% or less, Cu: 1.00% or less, Ni: 1.00% or less, Cr: 0.50% or less, and V: 0.05% or less, in which Pcm* (%) (=C+Si/30+(Mn+Cu+Cr)/20+Ni/60+Mo/2+V/10) is 0.20 or less. The steel plate has a volume fraction of bainite in a base material of 50% or more, and has a volume fraction of island martensite (MA) in a coarse-grain region reheated in a dual-phase temperature range of 5.0% or less. A slab having the chemical composition described above that is cast using a continuous casting method is reheated at a specified temperature, hot-rolled, and then subjected to accelerated cooling to a temperature of 550&#xb0; C. or lower and 250&#xb0; C. or higher.

Steel plate for thick-walled steel pipe, method for manufacturing the same, and thick-walled high-strength steel pipe

The present invention relates to a method for cooling a steel plate comprising the steps of: forming a water pool with jets of cooling water being injected to impinge on one another by using one slit-nozzle and a plurality of induced laminar flow nozzles, the slit nozzle being provided in a position on an upper surface side of the steel plate, and the induced laminar flow nozzles being provided in a position on a lower surface side of the steel plate along a transfer direction and a direction perpendicular to the transfer direction; and passing the steel plate into the water pool, wherein when a top portion of the steel plate passes over the induced laminar flow nozzles located at least on the side of highest upstream, a volume of the cooling water to be injected from each of the induced laminar flow nozzles is reduced. According to the method of the present invention, when on-line cooling is performed for a hot rolled steel plate, the top portion of the steel plate can be prevented from being super cooled, and the steel plate can therefore be uniformly cooled.

Method and device for cooling steel sheet

Method for manufacturing an ultra-high strength cold-rolled steel sheet

Continously annealed cold-rolled steel sheet excellent in balance

Blister-resistant steel sheet consists essentially of 0.0005 to 0.003 wt. % C, 0.10 to 2.2 wt. % Mn, 0.6 wt. % or less Si, 0.07 wt. % or less P, 0.025 wt. % or less S, 0.02 to 0.06 wt. % of sol. Al, 0.0035 wt. % or less N, 0.003 wt. % or less O, [(48/14)N+(48/32)S+4.times.(48/12)C] wt. % or less Ti and the balance being Fe and inevitable impurities; and smaller one of either Ti (wt. %) or [(48/14)N+(48/32)S] (wt. %) being [0.002 t.sup.2 +0.003] or more, where t is a thickness (mm) of the steel sheet. Method for producing blister-resistant steel sheet comprises preparing a cold rolled steel sheet having the composition of described above, and continuously annealing or continuous hot dip galvanizing by heating the steel sheet from room temperature to 650.degree.-720.degree. C. at a rate of 20.degree. C. sec or more and further to the soaking temperature above recrystallization temperature at a rate of 1.degree.-5.degree. C./sec.

Blister-resistant steel sheet and method for producing thereof

A heat treating method for a high strength aluminum alloy comprising the steps of: solution heat treating of an aluminum alloy consisting essentially of about 3 to 9 wt. % Zn, 1 to 6 wt. % Mg, 1 to 3 wt. % Cu, at least one element selected from the group consisting of 0.1 to 0.5 wt. % Cr, 0.1 to 0.5 wt. % Zr, 0.2 to 1.0 wt. % Mn, and the balance being Al, heating of the solution heat treated alloy to a temperature of a lower temperature zone of from 100.degree. to 140.degree. C. and optionally maintaining the alloy at a temperature within the lower temperature zone for a duration of time, reheating of the alloy to a temperature of an upper temperature zone of from 160.degree. to 200.degree. C. and optionally maintaining the alloy at a temperature within the upper temperature zone for a second duration of time, cooling of the alloy to a temperature of the lower temperature zone, and repeating the steps (2), (3), and (4) at least twice.

Heat treating method for high strength aluminum alloy

A heat-resistant TiAl alloy having excellent room-temperature fracture toughness, high-temperature oxidation resistance and high-temperature strength is disclosed. Said alloy consists essentially of from 29 to 35 wt. % aluminum, from 0.5 to 20 wt. % nobium, and at least one element selected from the group consisting of from 0.1 to 1.8 wt. % silicon, and from 0.3 to 5.5 wt. % zirconium, the balance being titanium and incidental impurities. Preferably impurities are limited to 0.6 wt.-% oxygen, 0.1 wt.-% nitrogen and 0.5 wt.-% hydrogen.

Heat-resistant TiAl alloy excellent in room-temperature fracture

Growing community of inventors

Tokyo, Japan

Seishi Tsuyama