Nippon Steel Corporation

Munetsugu Matsuo

Naoya Masahashi

Youji Mizuhara

Masao Kimura

Toshihiro Hanamura

Hideki Fujii

Hiroshi Takechi

Koichi Sakurai

Hiroo Suzuki

Keizo Hashimoto

Takashi Furukawa

Kenichi Miyazawa

Tadashi Nakayama

Toshiaki Mizoguchi

Osamu Akisue

Kazuo Koyama

Teruaki Yamada

Fumio Matsumoto

Mitsunobu Abe

Satohiro Hayami

Ryoji Terakado

Ichiro Shimbashi

Hiroshi Hayakawa

Soichi Izumi

Norimasa Uehara

Hideo Yokoyama

Ikushi Yoshida

TiAl-besed intermetallic compound alloys contain chromium and consist essentially of a dual-phase microstructure of .gamma. and .beta. phases, with the .beta. phase precipitating at .gamma. grain boundaries. The .beta. phase precipitating at .gamma. grain boundaries is 2% to 25% by volume fraction. A process for preparing TiAl-based intermetallic compound alloys comprises the steps of preparing a molten TiAl-based intermetallic compound alloy of a desired composition, solidifying the molten alloy, homogenizing the solidified alloy by heat treatment, and thermomechanically working the homogenized alloy.

TiAl-based intermetallic compound alloys and processes for preparing the

TiAl-based intermetallic compound alloys contain chromium and consist essentially of a dual-phase microstructure of .gamma. and .beta. phases, with the .beta. phase precipitating at .gamma. grain boundaries. The .beta. phase precipitating at .gamma. grain boundaries is 2% to 25% by volume fraction. A process for preparing TiAl-based intermetallic compound alloys comprises the steps of preparing a molten TiAl-based intermetallic compound alloy of a desired composition, solidifying the molten alloy, homogenizing the solidified alloy by heat treatment, and thermomechanically working the homogenized alloy.

Tial-based intermetallic compound alloys and processes for preparing the

Tial-based intermetallic compound alloys having superplasticity

This invention relates to TiAl based intermetallic compound alloy and process for producing; the object of this invention is to improve high temperature deformability. The alloy comprises basic components: Ti.sub.y AlCr.sub.x, wherein 1%.ltoreq.X.ltoreq.5%, 47.5%.ltoreq.Y.ltoreq.52%, and X+2Y.gtoreq.100%, and comprises a fine-grain structure with a .beta. phase precipitated on a grain boundary of equiaxed .gamma. grain having grain size of less than 30 .mu.m, and possessing a superplasticity such that the strain rate sensitivity factors (m value) is 0.40 or more and tensile elongation is 400% or more tested at 1200.degree. C. and a strain rate of 5.times.10.sup.-4 S.sup.-1.

Process for producing .gamma. and .beta. dual phase TiAl based

Ti-A1 intermetallic compound sheet and method of producing same

This invention relates to TiAl based intermetallic compound alloy and process for producing; the object of this invention is to improve high temperature deformability. The alloy comprises basic components: Ti.sub.y AlCr.sub.x, wherein 1%.ltoreq.X.ltoreq.5%, 47.5%.ltoreq.Y.ltoreq.52%, and X+ 2Y.gtoreq.100%, and comprises a fine-grain structure with a .beta. phase precipitated on a grain boundary of equiaxed .gamma. grain having grain size of less than 30 .mu.m, and possessing a superplasticity such that the strain rate sensitivity factors (m value) is 0.40 or more and tensile elongation is 400% or more tested at 1200.degree. C. and a strain rate of 5.times.10.sup.-4 S.sup.-1.

.gamma. and .beta. dual phase TiAl based intermetallic compound alloy

Conventionally, the silicon content of a grain-oriented electrical steel is approximately 3% at the maximum, since cold-rolling is difficult if the silicon content is high. Although conventional warm-rolling can occasionally mitigate the poor workability of a silicon steel having a high silicon content, it is impossible to control the texture of a cold-rolled strip and to completely prevent brittleness. The present invention provides a novel rolling method in which, due to the heating of a steel strip prior to the carrying out of cold-rolling, a desirable texture can be formed and rupture of the cold-rolled strip can be prevented. The strip is heated to within a temperature range, in which both the minimum temperature which is at least 200.degree. C. and at least equal to T.sub.L (.degree.C.)=(x-3.0).sup.2 .times.100, x being the silicon content in weight percent, and the maximum temperature which temperature range being is not more than 400.degree. C. and not more than T.sub.H (.degree.C.)=-200.times.log (1/y), y being the strain rate (second.sup.-1) during the cold rolling are determined so as to satisfy the temperature of the first cold rolling pass.

Process for producing a grain-oriented electrical steel sheet

A dual-purpose production plant for cold rolled steel sheets and hot-dip galvanized steel sheets having, successively disposed in series, a heating zone, a soaking zone, a primary cooling zone, an overaging zone equipped with a controlled cooling facility, a molten galvanizing zone, an intermediate cooling means, a secondary cooling zone, a temper rolling means, and a chemical treatment means, and a bypass for directly connecting the overaging zone and the secondary cooling zone with each other.

Dual-purpose plant for producing cold rolled steel sheet and hot-dip

A method of producing a dual phase structure cold rolled steel sheet having tensile strength 35 to 50 kg/mm.sup.2, yield ratio less than 60% and high elongation which comprises hot rolling and cold rolling by conventional process a steel containing 0.01 to 0.05% C, less than 0.2% Si, 1.7 to 2.5% Mn, 0.01 to 0.10 Al with the balance being Fe and unavoidable impurities, holding the produced steel sheet for 20 seconds to 20 minutes at a temperature 720.degree. to 850.degree. C., and cooling the steel sheet at a cooling speed between 3.degree. and 50.degree. C. per second and also above a value (.degree.C. per second) shown by following formulae:

Method of producing dual phase structure cold rolled steel sheet

A process for producing a cold rolled steel strip having excellent workability by a short-time continuous annealing, which process is constituted by hot rolling a low carbon steel slab of steel having a carbon content of from about 0.003 to 0.08% into a steel strip; cold rolling the hot rolled steel strip; rapidly heating the cold rolled steel strip to a recrystallization temperature range at a heating rate not less than 40.degree. C./second; slowly heating the thus rapidly heated steel strip to an annealing temperature at a heating rate ranging from 5.degree. to 30.degree. C./second; annealing the thus slowly heated steel strip at an annealing temperature T which is no lower than 700.degree. C. and no higher than the A.sub.3 transformation temperature and for an annealing time t no shorter than [8-0.03 (T-680)] seconds and no longer than [80-0.15 (T-680)] seconds, initially slowly cooling the thus annealed steel strip at a cooling rate less than 50.degree. C./second, and then rapidly cooling the strip at a cooling rate not less than 50.degree. C./second from a temperature T.sub.Q ranging from higher than 600.degree. C. to no higher than [T-0.027 (T-680)(.sqroot.t+23.7)].degree. C. to an over-ageing temperature range; and subjecting the thus cooled steel strip to an over-ageing treatment at a temperature ranging from 300.degree. to 500.degree. C. for a period of time ranging from 10 seconds to 5 minutes.

Process for producing deep-drawing cold rolled steel strips by

A method of producing a non-ageing cold rolled steel strip having excellent deep-drawability, with a r value of 1.5 or higher and ageing index of not higher than 3 kg/mm.sup.2 from an Al-killed steel with a lowered carbon content between 0.001 and 0.0035% and with no special additives such as titanium by a relatively low temperature coiling in the hot rolling, and a short-time continuous annealing without over-ageing, thus over-coming the disadvantages caused by a high temperature coiling and by additional over-ageing.

Method of producing non-ageing cold rolled steel strip with excellent

An apparatus for continuously producing a high strength dual-phase steel strip or sheet having a chemical composition which produces a dual-phase structure composed of ferrite grains and a low temperature transformed phase when rapidly cooled from the (.alpha.+.gamma.) temperature range or from the .gamma. temperature range. The apparatus has a continuous heat treatment furnace in which the strip moves vertically and which is composed of a heating zone, a soaking zone and a cooling zone, and conventional equipment associated therewith. The cooling zone has an upper hearth roll group, a lower hearth roll group and cooling equipment for cooling the strip at a rate in the range between 1.degree. and 300.degree. C./sec. for retaining the austenite in the steel of the strip. The hearth rolls of each hearth roll group are arranged to guide the strip coming from the soaking zone up and down through the cooling zone from the inlet end to the outlet end, alternately passing around the upper hearth rolls and the lower hearth rolls. The hearth roll at the position where the strip is subjected to straining and begins to work harden as a result of the bending, and the hearth rolls subsequent to such position, have diameters such that the strain induced phase transformation of the retained austenite and consequently the work hardening of the strip when it is turned around the hearth rolls is avoided.

Apparatus for continuously producing a high strength dual-phase steel

A slab or ingot of ferritic stainless steel for deep drawing applications is subjected to hot rolling, coiled at 450.degree. to 750.degree. C, subjected to warm rolling without cooling the coil by a rolling mill installed separately from the hot strip rolling mill, subjected to continuous annealing, and subjected to cold rolling and final annealing.

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Kawasaki, Japan

Munetsugu Matsuo