Kawasaki Steel Corporation

The Furukawa Electric Co., Ltd.

Toyota Motor Corporation

Furukawa Aluminum Co., Ltd.

Koichi Hashiguchi

Akio Tosaka

Masahiko Morita

Motohiro Nabae

Yoshihiro Matsumoto

Shinobu Okano

Kei Sakata

Toshio Irie

Takaaki Hira

Koji Yamato

Nobuo Totsuka

Makoto Imanaka

Yasuji Uesugi

Isao Takahashi

Naoki Nishiyama

Rinsei Ikeda

Yoichi Tobiyama

Toshio Ichida

Masaaki Kurihara

Nobuyuki Morito

Yoichiro Bekki

Fusao Togashi

Ichiro Tanokuchi

Yoshio Nakazato

Tomoo Tanaka

Makoto Isobe

Naohiko Soeda

Manabu Ohori

Toshitake Hanazawa

Junji Kawabe

Tateo Higashino

An aluminum alloy sheet combining excellent press formability and spot weldability is disclosed. A chromate film of about 1.0 to 50.0 mg/m.sup.2 expressed in terms of metallic chromium is formed as a first layer on an aluminum alloy sheet, and an organic resin film containing about 60-95% by weight of organic lubricant and having a thickness of 0.02 to 0.90 .mu.m in terms of dry thickness is formed as a second layer on the chromate film. As the organic lubricant, a high-density polyethylene having a mean molecular weight of about 900 to 15,000 and a density of about 0.93 g/ml or more is preferable. This aluminum alloy sheet can be effectively used for automobile body applications.

Aluminum alloy sheet having excellent press formability and spot

A method including preparing an aluminum scrap containing a total of about 0.3 to 2.0 wt % of Fe and Si; melting and then adjusting the material composition so as to attain an Mg content of about 3 to 10 wt % or a composition further containing at least one of the elements Cu, Mn, Cr, Zr and Ti, each in the amount of 0.02 to 0.5 wt %; subjecting the material to casting, hot rolling, cold rolling and continuous annealing to obtain an aluminum alloy sheet having a tensile strength of about 31 kgf/mm.sup.2 or more; and applying a lubricant surface coating to impart a coefficient of friction of not more than about 0.11.

Method of producing an aluminum alloy sheet excelling in formability

Aluminum alloy sheet with improved formability and method of production

A method of producing a hot-dip galvannealed steel sheet from a very-low-carbon cold-rolled steel sheet containing not less than 0.01 wt % but not more than 0.1 wt % of Ti, by subjecting the cold rolled steel sheet to a process conducted in a continuous hot-dip galvanizing system including a heat treatment, hot-dip galvanizing and a subsequent galvannealing. The method is characterized by the steps of: subjecting the cold-rolled steel sheet to a degreasing and an acid cleaning; subjecting the degreased and acid-cleaned steel sheet to a heat treatment conducted in a reducing gas atmosphere; and cooling the heat-treated steel sheet at a temperature not lower than 380.degree. C. but not higher than the hot-dip galvanizing bath temperature, before the steel sheet is subjected to the hot-dip galvanizing. The very-low-carbon cold- rolled steel sheet contains, besides not less than 0.01 wt % but not more than 0.1 wt % of Ti, not more than 0.005 wt % of C, not less than 0.01 wt % but not more than 0.1 wt % of Al, not less than 0.01 wt % but not more than 0.1 wt % of Ti, and the balance substantially incidental inclusions and Fe.

Method of producing hot-dip galvannealed steel sheet free of Ti

A continuous dip-plating apparatus for a steel strip has a pot containing a metal melt which forms a plating bath, a device for causing the steel strip to run through the plating bath such that the steel strip makes a turn around a sink roll in the plating bath so as to be pulled upwardly above the surface of the plating bath, and a wiping device disposed above the pot and adapted for adjusting the amount of deposition of the metal melt to the steel strip. The apparatus further has a pair of flow regulating plates for suppressing deposition of dross to the steel strip. The flow regulating plates are arranged in parallel with and in the vicinity of the portion of the steel strip running upwardly through the plating bath with the upper ends of the flow regulating plates being disposed substantially at the same level as the plating bath. Preferably, the height of the portion of each flow regulating plate below the level of the surface of the plating bath is not smaller than 50 mm, while the distance between each flow regulating plate and the steel strip is preferably not greater than 80 mm. It is also preferred that the upper end of each flow regulating plate is positioned between a level which is 10 mm below the surface of the plating bath and a level which is 50 mm above the surface of the plating bath.

Continuous dip-plating apparatus for steel strip

A flexible hot rolled steel sheet having an improved deep drawability comprises not more than 0.10 wt % of C, less than 0.20 wt % of Mn, 0.10-2.0 wt % of Cr, 0.002-0.100 wt % of Al, and the balance being Fe and inevitable impurities or further contains particular amounts of at least one of Ti, Nb and Zr and/or B. Such a hot rolled steel sheet has a tensile strength of not more than 35 kgf/mm.sup.2 and a total elongation of not less than 50%.

Flexible hot rolled steel sheets having improved deep drawability

A laminar flow cooling system employs a laminar flow nozzle comprising a pair of plate members defining slit through which cooling water flows to form a cooling water screen. One of the plate members of the laminar nozzle is deformable at least in a direction perpendicular to the cooling water flow direction to adjust the path area in the nozzle. At least one of the plate member is preferably responsive to the cooling water pressure to cause variation of the path area for adjusting the cooling water path area.

Method and system for cooling strip

A hot rolled steel sheet having a specific composition and having a specific small grain size of ferrite constituting the steel sheet has high resistances against secondary-work embrittlement and brazing embrittlement and is adapted for ultra-deep drawing. The specific small grain size of the ferrite can be obtained by limiting the hot rolling condition of a slab having the specific composition.

Hot rolled steel sheet having high resistances against secondary-work

A method of manufacturing a cold-rolled steel sheet having a good deep drawability is disclosed, wherein a hot rolled steel sheet having a composition of C.ltoreq.0.0035%, Si.ltoreq.1.0%, Mn.ltoreq.1.0%, Al:0.005-0.10%, P.ltoreq.0.15%, N.ltoreq.0.0035%, S.ltoreq.0.015%, Ti: (48/14N(%)+48/32S(%)) or {4.times.(C(%)+N(%))}.about.(3.48/12C(%)+48/14N(%)+48/32S(%)) and Nb: (0.2.93/12C(%)).about.(93/12C(%))% is cooled within 2 seconds after the completion of finisher rolling and then at an average cooling rate of not less than 10.degree. C./sec until it arrives at a coiling step, and then the cooled steel sheet is coiled at a temperature of not more than 710.degree. C., subjected to a cold rolling at a reduction of not less than 50%, which was subjected to a continuous annealing in a heatcycle inclusive of heating from 400.degree. C. to 600.degree. C. at a heating rate of not less than 5.degree. C./sec and soaking at a temperature range of 700.degree. C.-Ac.sub.3 point for 1 second or more.

Method of manufacturing a cold-rolled steel sheet having a good deep

The invention relates to a method of manufacturing a high-strength steel sheet by annealing the steel sheet after cold rolling. In order to obtain the low-yield ratio, high-strength steel sheet having high strength and good ductility, resistance to secondary cold-work embrittlement and spot weldability at low cost, the steel sheet containing 0.03-0.15% of P and specified amounts of C, Mn and Al as basic components and optionally containing, as a selective component, at least one element selected from a group of Si, Cr, Mo and B and a group of Nb, Ti, and V in such amounts as to meet the relation formula restricting the total content of Mn, Si, P, Cr and Mo is subjected to annealing under the conditions that the sheet is heated at a temperature of from Ac.sub.1 transformation point to 950.degree. C. for from 10 seconds to 10 minutes and cooled in such a control manner that an average cooling rate between 600.degree. C. and 300.degree. C. is not less than a specified critical cooling rate CR pertaining to the chemical composition and within a range of 15.degree.-200.degree. C./sec (FIGS. 1 and 4). The invention is suitable for the production of bumper, door guard bar, and the like in the automotive vehicles.

Low yield ratio high-strength annealed steel sheet having good ductility

Method of manufacturing a low yield ratio high-strength steel sheet

High tensile strength steel sheets having high press formability and excellent shape-fixability in which an average roughness in surface Ha is 0.4-1.8 .mu.m, PPI value is more than 80 at a cut off level of 0.5 .mu.m, the proportional limit stress is less than 20 kg/mm.sup.2 and the microstructure consists of ferrite grains dispersed with fine martensite islands, are produced by cold rolling a hot rolled steel sheet containing 0.005-0.15% of carbon, and manganese, if necessary boron, molybdenum, chromium, silicon, nickel and copper within a range of 0.27-3% of Mneq. shown by the following formula (1)

High tensile strength steel sheets having high press-formability and a

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Chiba, Japan

Koichi Hashiguchi