Abstract: Steel strips and methods for producing steel strips are provided. In an illustrated embodiment, a method includes continuously casting molten low carbon steel into a strip of no more than 5 mm thickness having austenite grains that are coarse grains of 100-300 micron width; and providing desired yield strength in the cast strip by cooling the strip to transform the austenite grains to ferrite in a temperature range between 850° C. and 400° C. at a selected cooling rate of at least 0.01° C./sec to produce a microstructure that provides a strip having a yield strength of at least 200 MPa. The low carbon steel produced desired microstructure.

Abstract: A steel for forming a high strength steel sheet contains, in mass %, C: at most 0.04%, Si: at most 0.4%, Mn: 0.5-3.0%, P: at most 0.15%, S: at most 0.03%, Al: at most 0.50%, N: at most 0.01%, and Mo: 0.01-1.0%. Steel sheet formed from the steel is suitable for use as automotive panels.

Abstract: A method of controlling a continuous steel strip casting process based on customer-specified requirements includes a general purpose computer in which product specifications of steel product ordered by a customer is entered. The computer is configured to automatically map the product specifications to process parameters/set points for controlling the continuous steel strip casting process in a manner to produce the customer ordered product, and in one embodiment produces a process change report detailing such process parameters/set points for operator use in physically implementing such process parameters/set points in the strip casting process. Alternatively, the computer may provide the process parameters/set points directly to the strip casting process for automatic control thereof in producing the customer ordered steel product.

Abstract: Apparatus for the rolling and heat treatment of elongated metal product of relatively small cross section, such as rods and bars, is described in which the elements required for the conduct of a variety of heat treatments are arranged in in-line disposition whereby any of several heat treatment procedures can be performed on the product without need for transferring the product to remotely located heat treatment facilities. The methods of performing various heat treatments through use of the disclosed apparatus are also described.

Abstract: The invention concerns a method for making a multiphase hot-rolled steel strip comprising an ultra-fast cooling operations, which consists in carrying out said ultra-fast cooling operation after controlled slow cooling of the strip on a conventional slow cooling table of the rolling mill. The controlled cooling constitutes a first slow cooling, at the output of the finishing mill, from an end-of-roll temperature to an intermediate temperature of about 750° C. to 500° C.; said first cooling determines the fraction of the first phase (ferrite) in the steel. The ultra-fast cooling (>150° C./s), which solidifies the resulting structure, lowers the temperature of the strip down to a coiling temperature, ranging between about 600° C. and room temperature, at which a second slow cooling is performed which results if the formation of the second phase (bainite or martensite).

Abstract: The invention relates to a high strength hot-dip galvanized and galvannealed steel sheets with excellent drawability for press forming and excellent plating adhesion that is useful as a member for automobiles, construction, electric devices and the like, and to a process for its manufacture. According to an embodiment of the invention, the steel sheet contains in terms of weight percent, C: 0.05-0.2%, Si: 0.2-2.0%, Mn: 0.2-2.5%, Al: 0.01-1.5%, Ni: 0.2-5.0%, P: <0.03% and S: <0.02%, the relationship between Si and Al being such that 0.4(%)≦Si+0.8 Al(%)≦2.0% and the remainder consisting of Fe and unavoidable impurities, the volume percentage of the retained austenite is 2-20% and the steel sheet surface wherein the relationship between the Ni and Si, Al in 0.5 &mgr;m of the steel sheet surface layer is such that Ni(%)≦¼ Si+⅓Al(%), has a Zn plating layer comprising Al: ≦1% with the remainder Zn and unavoidable impurities.

Abstract: A method of making a high-strength low-alloy (HSLA) hot rolled steel. A high-strength low-alloy steel is made by hot rolling a steel slab of a specified composition. The hot rolling step is carried out at an austenitic hot roll finishing temperature. The hot rolled steel is coiled at a temperature ranging from 1120° F. to 1180° F. The steel is characterized by a yield strength of at least 110 ksi. The steel may be further characterized by a ferrite-bainite microstructure.

Abstract: Process for the production of a hot rolled metal strip of very high strength, usable for shaping and particularly for stamping, characterized in that a steel of the following weight composition: carbon, 0.12-0.25%; manganese, 1-2%; aluminum, 0.03-2.5%; silicon, 0.03-2%; chromium, 0.04-2%; phosphorus, 0.02-0.09%; sulfur optionally up to 0.01%; titanium up to 0.15%; niobium up to 0.15%; vanadium up to 0.15%; is subjected to: rolling at a temperature below 880° C.; a first short cooling, carried out over a time less than 10 seconds, a second controlled cooling with a cooling speed V ref1 comprised between 20° C./sec. and 150° C./sec., the temperature at the end of the second cooling being comprised between 700° C. and 750° C., holding at a temperature level, a third cooling, also controlled, whose speed is comprised between 20° C./sec. and 150° C./sec., the temperature at the end of the third cooling being comprised between 350° C and 550° C.

Abstract: A method is disclosed for reducing the formation of wrinkles on metal strip subject to cooling in continuous heat treatment lines in which the strip passes through cooling zones through which cooling gas flows. The method includes the step of gradually modifying the cooling intensity at each change in the slope of the cooling cycle.

Abstract: A lower surface cooling box 12 is arranged between transfer rolls 11 on a runout table 3 and an upper cooling box 14 moving freely is arranged at a position corresponding to the cooling box 12 to eject cooling water to the steel strip symmetrically in the vertical direction. The steel strip passes the center of convergence of cooling water from upper and lower surfaces of the steel strip. A water breaking roll 16 is provided elevating freely at least at the outlet side rotating at the same peripheral speed as the transfer rolls and is rotated to lower concurrently with passing of the steel strip top at the cooling apparatus. The upper cooling box is also lowered concurrently to cool the steel strip.

Abstract: A method for producing hot-rolled strip and plates in a production plant having a continuous casting installation for slabs 100-180 mm thick, descaling sprays, a single- or multiple-stand rolling unit with or without edging, a cooling interval, a heating furnace, and a Steckel mill. Between the continuous casting installation and the heating furnace, only the skin layer of the previously descaled slab is deformed in-line, recrystallized during and after deformation, and then cooled in several stages to a temperature below the Ar3 transformation point and temporarily maintained there until the microstructural transformation of the recrystallized, fine-grained austenite to ferrite/pearlite has been completed.

Abstract: Method for reducing the formation of wrinkles on metal strip subjected to cooling in continuous heat treatment lines in which the said strip passes through cooling zones having boxes provided with means for blowing a cooling gas, comprising the step of gradually modifying the cooling intensity at each change in the slope of the cooling cycle.

Abstract: A hot-dip galvanized steel sheet is produced by rough rolling a steel, finish rolling the rough rolled steel at a temperature of Ar3 point or more, coiling the finish rolled steel at a temperature of 700° C. or less, and hot-dip galvanizing the coiled steel at a pre-plating heating temperature of Ac1 to Ac3. A continuous hot-dip galvanizing operation is performed by soaking a pickled strip at a temperature of 750 to 850° C., cooling the soaked strip to a temperature range of 600° C. or less at a cooling rate of 1 to 50° C. per second, hot-dip galvanizing the cooled strip, and cooling the galvanized strip so that the residence time at 400 to 600° C. is within 200 seconds. The steel sheet has a structure consisting essentially of ferrite and martensite.

Abstract: A steel sheet having a composition comprising C: 0.05-0.20 mass %, Si: 0.3-1.8 mass %, Mn: 1.0-3.0 mass %, Fe of the balance and inevitable impurities is subjected to a primary step of primary heat treatment and subsequent rapid cooling to Ms point or lower, a secondary step of secondary heat treatment and subsequent rapid cooling, and a tertiary step of galvanizing treatment and rapid cooling, so as to turn the structure of the steel sheet into a composite structure of 20% or more by volume of tempered martensite, 2% or more by volume of retained austenite, ferrite and a low-temperature transformation phase. A galvanized layer is deposited on the surface of the steel sheet. It is preferred to cool the steel sheet to 300° C. at a cooling rate of 5 ° C./sec. or more after the galvanizing treatment. After the galvanizing treatment, alloying treatment may be conducted.

Abstract: The object of the invention is an aluminum-killed low-carbon steel sheet comprising by weight between 0.022 and 0.035% of carbon, between 0.15 and 0.25% of manganese, between 0.040 and 0.070% of aluminum, between 0.004 and 0.006% of nitrogen, the remainder being iron and the inevitable trace impurities. The steel contains carbon in free state, a grain count per mm2 greater than 20000 and, in the aged condition, has a percentage elongation A% satisfying the relationship: (670−Rm)/14≦A%≦(720−Rm)/17 where Rm is the maximum rupture strength.

Abstract: A metal gasket for use in sealing between a cylinder head and a block of an engine includes at least one layer formed with at least one opening therethrough and a deformation feature in the form of a sealing bead, stopper, or both surrounding the opening. The gasket layer is fabricated of austemper-hardenable steel formed when in an annealed state and thereafter austempered to harden the layer and relieve residual forming stresses. During austempering, the layer is supported in a porous fixture that retains the layer against movement out of its plane while permitting it to move within its plane. The fixture has coarse expanded metal exoskeleton liner with wire mesh panels. The mesh liners maintain molten salt against the layers which acts as a thermal cushion to discourage warpage.

Abstract: In a heat treatment method for producing boundary layer-hardened long products and flat products of unalloyed or low-alloy steel, the workpiece is cooled for producing a martensitic grain within a boundary layer of the workpiece by repeating several sequential cooling process steps. Each sequential cooling process step has a cooling phase, in which the workpiece is cooled to a temperature below a martensite starting temperature for martensitic conversion of only a portion of the boundary layer of the workpiece, and a temporal stress-relief phase for relieving stress within already formed martensitic grain areas and already formed martensite/austenite boundary areas. Subsequently, the workpiece is cooled at a cooling rate below a lower critical cooling rate for cooling the workpiece core.

Abstract: Method for eliminating vibration of strip travelling continuously through zones of a heat treatment or coating line in which gas is blown onto a strip travelling continuously, particularly through devices which effect cooling by blowing gas in jets with which the lines for the continuous heat treatment or coating of metal strip are equipped, characterized in that this method consists in adjusting the pressure and/or the flow rate of the cooling gas to a value lower than the nominal value in a zone located at one edge of the strip, on one side thereof, and to a value lower than the nominal value on the opposite edge, located on the other side of the strip.

Abstract: The present invention provides a method of manufacturing a cold rolled steel sheet and a hot-dip zinc-coated steel sheet having excellent surface properties, an excellent resistance to natural aging and an excellent dent resistance of panel and, thus, adapted to the manufacture of steel sheet for outer panels of vehicles. The method comprises the steps of preparing steel consisting of 0.005 to 0.012% by weight of C, 0.01 to 0.4% by weight of Si, 0.15 to 1.0% by weight of Mn, 0.01 to 0.08% by weight of P, at most 0.02% by weight of S, 0.01 to 0.1% by weight of sol. Al, at most 0.004% by weight of N, and at least one element selected from the group consisting of 0.01 to 0.2% by weight of Nb and 0.04 to 0.1% by weight of Ti, and satisfying the condition 1.2≦(12/93) (Nb%/C%)+(12/48) (Ti*%/C%)≦2.5, applying a hot rolling and a cold rolling to the steel, soaking the cold rolled steel sheet at T(° C.) meeting a formula Ac3≧T(° C.

Abstract: Alloy steels that combine high strength and toughness with high corrosion resistance are achieved by a dislocated lath microstructure, in which dislocated martensite laths that are substantially free of twinning alternate with thin films of retained austenite, with an absence of autotempered carbides, nitrides and carbonitrides in both the dislocated martensite laths and the retained austenite films. This microstructure is achieved by selecting an alloy composition whose martensite start temperature is 350° C. or greater, and by selecting a cooling regime from the austenite phase through the martensite transition region that avoids regions in which autotempering occurs.

Abstract: An ultra-high strength steel having excellent ultra-low temperature toughness, a tensile strength of at least about 930 MPa (135 ksi), and a microstructure comprising predominantly fine-grained lower bainite, fine-grained lath martensite, or mixtures thereof, transformed from substantially unrecrystallized austenite grains and comprising iron and specified weight percentages of the additives: carbon, silicon, manganese, copper, nickel, niobium, vanadium, molybdenum, chromium, titanium, aluminum, calcium, Rare Earth Metals, and magnesium, is prepared by heating a steel slab to a suitable temperature; reducing the slab to form plate in one or more hot rolling passes in a first temperature range in which austenite recrystallizes; further reducing said plate in one or more hot rolling passes in a second temperature range below said first temperature range and above the temperature at which austenite begins to transform to ferrite during cooling; quenching said plate to a suitable Quench Stop Temperature; and stop

Abstract: A method for producing a cold-rolled steel sheet or strip with good formability, especially stretch formability, for making pressings with a high buckling resistance from a steel comprising (in % by mass): 0.01 to 0.08% C, 0.10 to 0.80% Mn, maximum 0.15% Si, 0.015 to 0.08% Al, a maximum 0.005% N, 0.01 to 0.04% Ti and/or Nb, whose contents exceeding the quantity necessary for stoichiometric binding of the nitrogen, ranges from 0.003 to 0.015% Ti or 0.0015 to 0.008% Nb, and a maximum 0.15% in total of one or several elements from the group copper, vanadium, nickel, the remainder being iron, including unavoidable impurities, including a maximum 0.08% P and a maximum 0.02% S, comprises preheating the cast slab to a temperature exceeding 1050.degree. C., hot-rolling at a final temperature ranging from over the Ar.sub.3 temperature to 950.degree. C., coiling the hot-rolled strip at a temperature ranging from 550 to 750.degree. C.

Abstract: A variable rate quench system allows the cooling of a heated workpiece to be controlled more closely. A liquid quenchant used in the system has an initial temperature, density and heat extraction index. The system comprises a first tank containing the liquid quenchant and to receive the workpiece and a second tank communicated to the first tank. The first tank has a means for agitating the liquid quenchant around the workpiece and a supply of make-up liquid quenchant communicated thereto. The second tank has a slurry of a non-liquid solid phase quenchant modifier and a means for selectively controlling addition of the slurry to the first tank. A real time data acquisition system acquires and analyzes temperature, density and agitation rate of the liquid quenchant, calculates an instantaneous heat extraction index of the liquid quenchant and compares the difference between the calculated index and a predetermined ideal index. Corrective action to minimize the difference is then taken.

Abstract: Method for heat treating rolled stock leaving a rolling train (12), wherein the rolled stock (13) undergoes a rapid cooling treatment in a rapid cooling assembly (11) located immediately downstream of the last rolling pass, the first cooling step being followed by a temperature-equalisation step in air and at least by a second cooling treatment before being discharged and collected, the temperature-equalisation step in air and the at least second cooling treatment being set so as not to modify the surface and inner crystalline structure of the rolled stock (13) which has formed at the outlet of the first cooling treatment, the at least second cooling treatment being followed by a short segment of temperature-equalisation in air and then directly by the collection of the rolled stock (13) into compact form, such as rolls coils bundles or packs, wherein the slow cooling of the rolled stock (13) collected in compact form leads to the transformation of the crystalline structure in the stable structures.

Abstract: A belt for use in the casting of metals and a method for its manufacture in which a metal belt is first subjected to heat treatment, quenching and tempering to improve its strength and decrease its stretchability. Then the belt is treated to introduce surface irregularities to promote uniformity of heat transfer and to allow collection of surface gases and then the belt is subjected to further thermal treatment under controlled conditions to form an oxide layer thereon to minimize adhesion between the belt and the metal deposited thereon.

Abstract: Apparatus which eliminates the risk of forming wrinkles on a strip conveyed through a cooling furnace of a continuous heat-treatment plant, especially an annealing or galvanizing furnace, through which the strip is conveyed by rolls, the latter being heated by contact with the strip over its width, the risk of forming wrinkles occuring during a change of strip width when the following strip is wider, the latter consequently passing over rolls that have preserved the imprint of the thermal expansion due to the previous strip, wherein the heating elements are positioned close to and beneath the rolls, over the entire width of the furnace, and, on the opposite side of the rolls from the said heating elements, panels are positioned which are aligned so as, together with the wall of the furnace, to form a warm chamber, the continuously moving strip serving as a heat shield so that only that part of the roll which is not covered by the strip is heated by the said heating elements.

Abstract: In a method of continuously annealing steel strip comprising a heating step (A), a soaking step (B), a primary cooling step (C) including a rapid cooling step at least in a second half thereof, an overaging step (D), and a final cooling step (E), inert atmosphere gas containing H.sub.2 gas in the concentration of 30-60% is employed as cooling gas for use in the rapid cooling step, the blowoff temperature of the cooling gas is 30.degree.-150.degree. C., and the blowoff speed of the cooling gas is 100-150 m/sec. The primary cooling method in continuously annealing steel strip provides the primary cooling step (C) including the rapid cooling step which can be carried out with a high efficiency and a low cost.

Abstract: A hot-rolled sheet steel for deep drawing, characterized in that it has the following composition:______________________________________ carbon >0.010 wt. % and <0.080 wt. % manganese >0.1 wt. % and <0.5 wt. % aluminum >0.02 wt. % and <0.08 wt. % silicon <0.1 wt. % phosphorus <0.04 wt. % sulfur <0.025 wt. % titanium <0.05 wt. % nitrogen <0.009 wt. % boron >0.001 wt. % and <0.01 wt. % copper >0.1 wt. % and <0.8 wt. % nickel >0.05 wt. % and <0.6 wt. %.

Abstract: After a starting material of steel comprising C: 0.001-0.20 wt %, Si: 0.01-0.50 wt %, Mn: 0.05-2.0 wt %, P: not more than 0.05 wt %, S: not more than 0.05 wt %, sol.Al: 0.01-0.10 wt %, N: not more than 0.020 wt % and the balance being Fe and inevitable impurities is heated above AC.sub.3 point, rough rolling is completed within a temperature range of (Ar.sub.3 point+100.degree. C.)-(Ar.sub.3 point+50.degree. C.), and super-high pressure descaling is carried out under conditions satisfying a jetting pressure of not less than 25 kgf/cm.sup.2 and a liquid quantity density of not less than 0.002 liter/cm.sup.2, and subsequently finish rolling at a rolling reduction of not less than 80% above Ar.sub.3 point of a rolling completion temperature is started in 5 seconds and coiling is carried out below 700.degree. C., whereby hot rolled steel sheets having a surface roughness Ra of not more than 0.8 .mu.m and an average scale thickness of not more than 4 .mu.

Abstract: A method for producing a dual phase ferrite-martensite steel product from a cold rolled stainless steel. The method includes a step of rapidly heating the steel to annealing temperature in less than 30 seconds, followed by a step of cooling the heated steel at a cooling rate sufficient to transform austenite to martensite.

Abstract: A method of cooling steel sections which are hot from rolling by means of shock-like cooling following the rolling process so as to form a martensitic surface layer, and by subsequently autogenously tempering this surface layer by means of core heat to obtain a tough-resistant structure with an austenitic remaining cross-section, wherein the method is used in connection with types of steel which, with uncontrolled cooling in air, would directly transform from the austenitic phase into martensite because of their alloying elements from the group Cr, Mn, Mo, Ni and other suitable elements.

Abstract: A steel composition useful for the manufacture of articles and components having high abrasion resistance.

Abstract: A steel plate has a minimum yield strength of 65 ksi, a tensile strength minimum of 78 ksi, a minimum elongation in 8 inches and 2 inches for a plate up to 24 inches in width of 18% and 22% respectively and a minimum elongation of 16% and 20% for a plate wider than 24 inches and a minimum Charpy V-notch energy of 30 ft-lb longitudinal and 20 ft-lb transverse at -40.degree. F. and a composition of the following weight percentages:a) carbon 0.03-0.10, b) manganese 1.10-1.65, c) phosphorous 0.025 max, d) sulfur 0.010 max, e) silicon 0.10-0.50, f) nickel 0.40 max, g) chromium 0.20 max, h) molybdenum 0.03-0.08, i) copper 0.35 max, j) vanadium 0.04-0.10, k) columbium 0.02-0.06, l) aluminum 0.03-0.08 and treated by heat treating and/or rolling.

Abstract: A method for manufacturing a canning steel sheet with non-aging property and superior workability uses, as a starting material, an ultra-low-carbon steel slab composed of from 0.0015% to 0.0100% by weight C, up to 0.20% by weight Si, from 0.10% to 1.20% by weight Mn, from 0.02% to 0.10% by weight Al, from 0.005% to 0.040% by weight P, up to 0.015% by weight S, up to 0.005% by weight N, and balance iron and unavoidable impurities. The manufacturing method includes hot rolling the steel, cold rolling the steel at a reduction ratio not less than 70% after pickling, and recrystallization annealing the steel by using a continuous annealing furnace in an atmosphere having a hydrogen content not less than 3% and a dew point not lower than -20.degree. C. at a temperature not lower than 730.degree. C. so that the content of remained C in the steel is kept less than 0.0015% by weight. At least one element selected from Nb, Ti and B may be added in predetermined amounts to the above composition.

Abstract: A thin steel sheet having a structure comprising at least one member selected from a transgranular acicular ferrite and a bainite having a packet size of 30 to 300 .mu.m, in a proportion of not less than 95% of the structure, is produced by subjecting a steel comprising, in terms of % by weight, 0.01 to 0.20% of C, 0.005 to 1.5% of Si, 0.05 to 1.5% of Mn and not more than 0.03% of S and optionally 0.0005 to 0.0100% of Ca or 0.005 to 0,050% of REM with the balance consisting of Fe and unavoidable impurities to continuous casting into a thin cast strip having a casting thickness in the range of from 0.5 to 5 mm, cooling the thin cast strip from the temperature range of from the casting temperature to 900.degree. C. to the temperature range of from 650.degree. to 400.degree. C. at an average cooling rate of not less than V (.degree.C./sec) represented by the following formula (1); and coiling the cooled strip at a temperature of not more than 650.degree. C.:log V.gtoreq.0.5-0.8 log Ceq (.degree.C.

Abstract: A process for making steel wear plates for use as railroad car truck side frame/bolster damping components utilizes the sequential steps of heating, pressing, quenching and then tempering. The heating process includes bringing the wear plate to a temperature of approximately 1750.degree. F. so that the plate is essentially 100 percent austenite. Generally uniform pressure is applied to the plate while heated to bring the plate to a desired flatness. Quenching fluid is thereafter applied to the flattened plate, while maintaining pressure thereon, to bring the plate to a predetermined brinnell hardness, a predetermined temperature, and a metallurgical characteristic of at least 90 percent martensite. The plate is thereafter tempered at a temperature of from 910.degree.-940.degree. F. for a period of time sufficient to bring the plate to a brinnell hardness less than the hardness after quenching.

Abstract: In an apparatus for continuously annealing a steel strip after cold rolling, stable operation of the annealing apparatus can be obtained by preventing slippage of bridle rolls and hearth rolls. The diameter D of a bridle roll is set so that a surface pressure p defined by an equation p=h(.sigma..sub.1 +.sigma..sub.2)/D can be 10 kPa (kilopascal) or more, wherein the unit tension of a steel strip at the inlet side of the bridle roll and hearth rolls of the apparatus is .sigma..sub.1, the unit tension at the outlet side is .sigma..sub.2, the thickness of the steel strip is h and the diameter of the bridle roll is D.

Abstract: The present invention provides a non-aging at room temperature ferritic single-phase cold-rolled steel sheet or hot-dip galvanized steel sheet for deep drawing and having excellent fabrication embrittlement resistance and paint-bake hardenability, by heating a slab comprising, in terms of % by weight, 0.0001 to 0.0015% of C, not more than 1.2% of Si, 0.03 to 3.0% of Mn, 0.01 to 0.15% of P, 0.0010 to 0.020% of S, 0.005 to 0.1% of Al, 0.0001 to 0.0080% of N and 0.0001 to 0.0030% of B and optionally 0.1 to 3% of Cr with the balance consisting of Fe and unavoidable impurities, hot-rolling the heated slab at a finishing temperature of not lower than (Ar.sub.3 --100).degree. C., cooling the hot-rolled coil within 1 sec after the hot rolling at a rate of not less than 50.degree. C./sec from the finishing temperature to a temperature in the range of from 600.degree. to 750.degree. C.

Abstract: Disclosed is a process for producing seamless steel pipes or flat products (strip or sheet) for pipes or vessels which are intended for the conveyance, transport or processing of gaseous or liquid hydrocarbons containing CO.sub.2 and water and possibly small proportions of H.sub.2 S and are resistant to stress crack corrosion and have good welding properties at the same time and a 0.2-percent elongation limit of at least 450 N/mm.sup.2. The process uses a nickel-containing steel of the following composition (percent by weight): min. 0.015% C, 0.15-0.50% Si, max. 2.00% Mn, max. 0.020% P, max. 0.003% S, 12.0-13.8% Cr, 0.002-0.02% N, 0.01-0.05% Nb, remainder iron and usual impurities. It is presently suggested that the nickel content is limited to a maximum of 0.25%, the manganese content amounts to at least 1.0%, the carbon content is limited to 0.035%, and 0.01 to 1.2% molybdenum is contained as additional alloying component.

Abstract: A steel plate having a high toughness, low yield ratio and high fatigue strength is provided by preserving the fine metallographical microstructure of martensite or bainite while austenitizing extremely fine portions of the microstructure, and during cooling, dispersing the portions as martensite, retained austenite, cementite or mixture thereof in a tempered martensite or tempered bainite phase.

Abstract: Deep drawability and aging resistibility as required are imparted to cold rolled steel sheet by controlling the amount of C, starting temperatures of rapid cooling and cooling rate in a proposed continuous annealing process.

Abstract: In a method of producing a high-strength cold-rolled steel sheet excelling in deep drawability, a steel material is used which consists of: a basic composition including 0.01% or less of C, 0.1 to 2.0% of Si, 0.5 to 3.0% of Mn, 0.02 to 0.2% of P, 0.05% or less of S, 0.03 to 0.2% of Al, 0.01% or less of N, 0.001 to 0.2% of Nb, and 0.0001 to 0.008% of B in such a way that the respective contents of C, Nb, Al, N, Si, Mn and P satisfy the following formulae:5.ltoreq.Nb/C.ltoreq.30, 10.ltoreq.Al/N.ltoreq.80, and 16.ltoreq.(3.times.Si/28+200 .times.P/31)/(Mn/55).ltoreq.40; Fe remnant; and inevitable impurities, the method including the steps of:performing rolling on the steel material with a total reduction of 50% or more and 95% or less while effecting lubrication thereon in a temperature range of not higher than the Ar.sub.3 transformation temperature and not lower than 500.degree. C.

Abstract: The invention relates to a high strength cold rolled steel sheet having excellent non-aging property at room temperature and excellent drawability, said steel sheet having a dual-phase structure composed of a high-temperature transformed ferrite phase and a low-temperature transformed ferrite phase having high dislocation density.The invention also relates a high strength cold rolled steel sheet having excellent non-aging property at room temperature and bake hardenability, as well as excellent drawability. This steel sheet is produced by preparing a hot-rolled steel sheet, cold rolling the hot-rolled steel sheet at a rolling reduction not smaller than 60%, annealing the cold rolled steel sheet at a temperature which is not lower than the .gamma. transformation start temperature but below the A.sub.c3 transformation temperature, and cooling the annealed steel sheet at a rate not smaller than 5.degree. C./sec but not greater than 100.degree. C./sec.

Abstract: The steel having improved deep-drawing properties is characterized in that it contains carbon in a proportion of less than 0.015%, manganese in a proportion of from 0.15 to 0.25%, sulfur in a proportion of less than 0.012% and aluminum in a proportion of less than 0.04%.This steel is intended for the production of thin sheet metal intended for deep-drawing, in accordance with a process comprising, in particular, the following operations:production, in a converter, of a steel having the above composition;hot-rolling entirely in the austenitic region;winding at a temperature higher than 650.degree. C.;continuous annealing, after cold-rolling, at a temperature below 700.degree. C.