Abstract: In a martensitic stainless steel tube according to the present invention, the content is determined by each of elements C, Si, Mn and Cr, and the bubble content ratio is further prescribed in accordance with the scale thickness on the outer surface of the steel tube, so that defects can be detected with high precision in the non-destructive inspection, such as ultrasonic test or the like. This allows the non-destructive inspection to be carried out with high efficiency. Moreover, there is another advantage that the weather resistance can be enhanced. The steel tube according to the present invention and the manufacturing method thereof can be suitably used in all of the technical fields in which a martensitic stainless steel tube having equal chemical composition is treated.

Abstract: A high-strength hot-rolled steel sheet excellent in shape fixability having ferrite or bainite as the phase of the largest volume percentage, satisfying all of the following at least at ½ sheet thickness: a mean value of X-ray random intensity ratio in the orientation component group of {100}<011> to {223}<110> to X-ray random diffraction intensity ratio of at least 2.5; a mean value of X-ray random intensity ratio in the three crystal orientation components of {554}<225>, {111}<112>, and {111}<110> to X-ray random diffraction intensity ratio of 3.5 or less; an X-ray intensity ratio to X-ray random diffraction intensity ratio at {100}<011> of at least the X-ray random intensity to X-ray random diffraction intensity ratio at {211}<011>; and an X-ray random intensity ratio to X-ray random intensity ratio diffraction intensity ratio at {100}<011> of at least 2.

Abstract: Accordingly to an exemplary embodiment of the present invention, a high tensile strength, refractory steel can be provided which comprises, in mass %, approximately C: 0.04 to 0.14%, Si: 0.50% or less, Mn: 0.50 to 2.00%, P: 0.020% or less, S: 0.010% or less, Nb: 0.01 to 0.05%, Mo: 0.30% or more and less than 0.70%, Al: 0.060% or less, N: 0.0010 to 0.0060%, and the balance consisting of iron and unavoidable impurities. For example, a weld crack sensitive composition PCM can be defined by the following equation may be about 0.25% or less: PCM=C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B. An area fraction of polygonal ferrite or pseudo polygonal ferrite in a ¼ thick position in the plate thickness direction of the steel plate of the final rolling product is about 10% or less.

Abstract: A method of manufacturing a hot-formed steel product is provided, by which when a steel sheet is subjected to hot forming, excellent forming can be achieved without causing break or a crack during forming. When a steel sheet is subjected to hot forming to obtain a hot-formed product, the steel sheet is heated to be austenitized, then the steel sheet is cooled to a temperature range of martensite transformation start temperature Ms or less at an average cooling rate of 20° C./sec or more, and then the steel sheet obtained in this way is heated to Ac1 transformation temperature or more, then subjected to hot forming, thereby an excellent hot-formed product is obtained.

Abstract: A martensitic alloy in which the ASTM grain size number is at least 5, including (wt. %) up to about 0.5% C, at least about 5% Cr, at least about 0.5% Ni, up to about 15% Co, up to about 8% Cu, up to about 8% Mn, up to about 4% Si, up to about 6% (Mo+W), up to about 1.5% Ti, up to about 3% V, up to about 0.5% Al, and at least about 40% Fe.

Abstract: The invention concerns a method for making an abrasion-resistant steel part consisting of 0.1%?C?0.23%; 0%?Si?2%; 0%?AI?2%; 0.5%?Si+AI?2%; 0%?Mn?2.5%; 0%?Ni?5%; 0%?Cr?5%; 0%?Mo?1%; 0%?W?2%; 0.05%?Mo+W/2?1%; 0%?B?0.02%; 0%?Ti?0.67%; 0%?Zr?1.34%; 0.05%?Ti+Zr/2?0.67%; 0%?S?0.15%; N<0.030, optionally 0% to 1.5% of Cu; optionally Nb, Ta and V such that Nb/2+Ta/4+V?0.5 %; optionally Se, Te, Ca, Bi, Pb contents ?0.1%; the rest being iron and impurities. Additionally: 0.095%?C*=C?Ti/4?Zr/8+7×N/8, Ti+Zr/2?7×N/2?0.05% and 1.05×Mn+0.54×Ni+0.5O×Cr+0.3×(Mo++W1/2)1/2+K>1.8, with K=1 if B?0.0005% and K=0 if B<0.0005%. After austenitization, the method consists in: cooling at a speed >0.5° C./s between AC3 and T=800?270×C*?90×Mn?37×Ni?70×Cr?83×(Mo+W/2) and about T?50° C.; then cooling at a speed 0.1<Vr<150×ep?1.7 between T and 100° C., (ep=thickness of plate in mm); cooling down to room temperature and optionally planishing. The invention also concerns the resulting plate.

Abstract: The invention concerns a method for making an abrasion resistant steel plate having a chemical composition comprising: 0.35%?C?0.8%, 0%?Si?2%; 0%?AI?2%; 0.35%?Si+AI?2%; 0%?Mn?2.5%; 0%?Ni?5%; 0% ?Cr?5%; 0%?Mo?0.050; 0%?W?1%; 0,1%?Mo+W/2?0.5%; 0%?B?0.02%; 0%?Ti?2%; 0%?Zr?4%; 0.05%?Ti+Zr/2?2%; 0%?S?0.15%; N?0,03; optionally 0% to 1.5% of Cu; optionally Nb, Ta or V with Nb/2+Ta/4 +V?0.5%; optionally less than 0.1% of Se, Te, Ca, Bi or Pb; the rest being iron and impurities; the composition satisfying: 0.1 %<C*=C?Ti/4?Zr/8+7×N/8?0.55% and 1.05×Mn+0.54×Ni+0.5O×Cr+0.3×(Mo+W/2)1/2+K>1.8, with K=0.5 if B ?0.0005% and K=0 if B<0.0005% and Ti+Zr/2?7×N/2?0.05%; hardening after austenitization while cooling at a speed >0.5 ° C./s between a temperature >AC3 and ranging between T=800?270×C*?9O×Mn?37×Ni?70×Cr?83×(Mo+W/2) and T?50° C.; then at a core speed Vr<1150×ep?1.7 between T and 100° C., (ep=plate thickness in mm); cooling down to room temperature. The invention also concerns the resulting plate.

Abstract: The method of making steel with carbide banding entails using steel with undissolved carbides distributed within the steel for forming steel with carbide banding, wherein the steel is about 0.3 weight percent to about 2.2 weight percent carbon and at least 0.003 weight percent of chromium, molybdenum, aluminum, vanadium, tungsten, or a similar carbide forming element; then, deforming the steel with undissolved carbides to create steel with carbide banding upon cooling, heating the steel with undissolved carbides for a specified time ranging at a specified temperature to form an austenitic steel with undissolved carbides, and cooling the austenitic steel with undissolved carbides to maintain the undissolved carbides within a crystalline matrix forming steel with carbide banding.

Abstract: The invention is method of making steel with carbide banding obtaining steel with undissolved carbides distributed within the steel for forming steel with carbide banding, wherein the steel is about 0.3 weight percent to about 2.2 weight percent carbon and at least 0.003 weight percent of chromium, molybdenum, aluminum, vanadium, tungsten, or a similar carbide forming element; then, deforming the steel with undissolved carbide, moving a portion of the steel with undissolved carbides, heating the steel with undissolved carbides for a time ranging from about 5 minutes to about 12 hours at a temperature above an A-sub 1 temperature and below 50 degrees Fahrenheit of an A-sub 3 temperature to form an austenitic steel with undissolved carbides, and cooling the austenitic steel with undissolved carbides to maintain the undissolved carbides within a crystalline matrix forming steel with carbide banding.

Abstract: Disclosed is a steel sheet that exhibits an ultra-high strength after hot press forming followed by rapid cooling, and an enhanced yield strength after painting. The steel sheet has a composition comprising 0.1% to 0.5% by weight of C, 0.01% to 1.0% by weight of Si, 0.5% to 4.0% by weight of Mn, 0.1% by weight or less of P, 0.03% by weight or less of S, 0.1% by weight of soluble Al, 0.01% to 0.1% by weight of N, 0.3% by weight or less of W, and the balance Fe and other inevitable impurities. Further disclosed are a hot-pressed part made of the steel sheet and a method for manufacturing the hot-pressed part. The hot-pressed part achieves a high increment in yield strength after heat treatment for painting while ensuring an ultra-high tensile strength. Furthermore, the hot-pressed part exhibits superior adhesion to a coating layer, good surface appearance and improved corrosion resistance after painting.

Abstract: A common-rail injection system is provided for a diesel engine and has excellent internal pressure fatigue resisting characteristics, vibrational fatigue resisting characteristics and cavitation resisting property and sheet face flawing resisting property, and can be made thin and light in weight. A main pipe rail is manufactured by transformation induced plastic type strength steel. After the main pipe rail is processed, residual austenite is generated by heat treatment, and the reduction processing of stress concentration of a branch hole and a main pipe rail side flow passage crossing portion is performed. Further, it is preferable that an induced plastic transformation is generated on the inner surface of the main pipe rail by autofrettage processing, and compression residual stress is left.

Abstract: The invention relates to a method for producing a siderurgical product made of carbon steel having a high copper content, according to which: —a liquid steel having the composition: 0.0005%?1%; 0.5?Cu?10%; 0?Mn?2%; 0?Si?5% 0?Ti?0.5%; 0?Nb?0.5%; 0?Ni?5%; 0?Al?2%, the remainder being iron and impurities, is produced;—said liquid steel is poured directly in the form of a thin strip having a thickness of no more than 10 mm;—the strip is subjected to forced cooling and/or is surrounded by a non-oxidizing atmosphere while having a temperature of more than 1000? C.; —said thin strip is hot rolled at a reduction rate of at least 10%, the temperature at the end of the rolling process being such that all of the copper is still in a solid solution in the ferrite and/or austenite matrix;—and the strip is coiled. The invention also relates to a siderurgical product obtained according to said method.

Abstract: A thick-walled seamless steel pipe for line pipe which has a high strength and improved toughness and corrosion resistance in spite of the thick wall and which is suitable for use as a riser and flow line has a chemical composition comprising, in mass percent, C: 0.02-0.08%, Si: at most 0.5%, Mn: 1.5-3.0%, Al: 0.001-0.10%, Mo: greater than 0.4%-1.2%, N: 0.002-0.015%, at least one of Ca and REM in a total amount of 0.0002-0.007%, and a remainder of Fe and impurities, with the impurities having the content of P: at most 0.05%, S: at most 0.005%, and O: at most 0.005%, the chemical composition satisfying the inequality: 0.8?[Mn]×[Mo]?2.6, wherein [Mn] and [Mo] are the numbers equivalent to the contents of Mn and Mo, respectively, in mass percent.

Abstract: A steel sheet excellent in mechanical strength, workability and thermal stability and suited for use as a raw material in such fields of manufacturing automobiles, household electric appliances and machine structures and of constructing buildings, and a manufacturing method thereof. are provided. The steel sheet is a hot-rolled steel sheet of carbon steel or low-alloy steel, the main phase of which is ferrite, and is characterized in that the average ferrite crystal grain diameter D (?m) at the depth of ¼ of the sheet thickness from the steel sheet surface satisfies the relations respectively defined by the formulas (1) and (2) given below and the increase rate X (?m/min) in average ferrite crystal grain diameter at 700° C. at the depth of ¼ of the sheet thickness from the steel sheet surface and said average crystal grain diameter D (?m) satisfy the relation defined by the formula (3) given below: 1.2?D?7 ??formula (1) D?2.7+5000/(5+350·C+40·Mn)2 ??formula (2) D·X?0.

Abstract: A ferrous seal sliding part excellent in heat crack resistance, seizure resistance and abrasion resistance is provided. The ferrous seal sliding part has a seal sliding surface, wherein the seal sliding surface has a quench hardened layer having a structure in which a martensite parent phase forms a solid solution with carbon of 0.15 to 0.6 wt % and contains cementite dispersed therein in a content of 3 to 50% by volume.

Abstract: The present invention relates to A high strength steel sheet having a structure which is mainly composed of MD structure (Micro Duplex structure) comprising a ferrite matrix, and as a secondary phase, martensite or martensite and retained austenite, finely dispersed in said matrix, wherein the proportion that the MD structure occupies in the whole structure is 90% or more, wherein the proportion that the secondary phase present in the whole structure occupies in the whole structure is from 10 to 60%, wherein the secondary phase in the MD structure is present in ferrite grains and at grain boundary, in which the proportion of the secondary phase present in the ferrite grains is 50% or more, and wherein the average grain size of the secondary phase in the whole structure is 3 ?m or less. The secondary phase is constituted of martensite, or martensite and retained austenite.

Abstract: A welding structural steel product exhibiting a superior heat affected zone toughness, comprising, in terms of percent by weight, 0.03 to 0.17% C, 0.01 to 0.5% Si, 0.4 to 2.0% Mn, 0.005 to 0.2% Ti, 0.0005 to 0.1% Al, 0.008 to 0.030% N, 0.0003 to 0.01% B, 0.001 to 0.2% W, at most 0.03% P, at most 0.03% S, at most 0.005% O, and balance Fe and incidental impurities while satisfying conditions of 1.2?Ti/N?2.5, 10?N/B?40, 2.5?Al/N?7, and 6.5?(Ti+2Al+4B)/N?14, and having a microstructure essentially consisting of a complex structure of ferrite and pearlite having a grain size of 20 ?m or less. The method includes the steps of preparing a slab of the above-described composition, heating the slab to 1,100° C. to 1,250° C. for 60-180 minutes, hot rolling the heated slab in an austenite recrystallization range at a 40% or more rolling reduction followed by controlled cooling.

Abstract: The high carbon steel wire rod contains 0.65% to 1.20% of C, 0.05% to 1.2% of Si, 0.2% to 1.0% of Mn, and 0.35% or less (including 0%) of Cr, further contains P and S each in an amount restricted to 0.02% or less, where 80% or more of the metal structure is constituted by a pearlite structure; and an average tensile strength TS and an average lamellar spacing ? of the high carbon steel wire rod show the relation of TS?8700/?{square root over ( )}(?/Ceq)+290 in which Ceq=% C+% Mn/5+% Cr/4. The high carbon steel wire rod can omit a patenting treatment before or during wire drawing, is superior in wire drawability, and exhibits a low drawing resistance in a wire drawing die in an as-hot-rolled state.

Abstract: Low carbon carburizing (surface hardening) and higher carbon through hardening steels primarily containing molybdenum, vanadium and nickel and, to a lesser amount, chromium used for rolling contact bearings, gears and other similar applications where high hardness at elevated temperatures is required. The alloy steel includes, in % by weight: 0.05% to 1.25% C; up to 1.25% Cr; 0.40% to 4% Mn; up to 4.0% Mo; up to 2.0% V; 1.0% to 3.0% Ni; 4% to 8% (Mo+V+Ni+Cr); less than 0.20% Si; and balance Fe plus incidental additions and impurities. The method for providing a steel having improved hardness at elevated temperatures includes the steps of: (a) providing an alloy including, in % by weight: less than 1.25% Cr, 0.4% to 4% Mn, up to 4% Mo, up to 2% V, 1 to 3% Ni, 4% to 8% (Mo+V+Ni+Cr), less than 0.2% Si, a C content selected from one of 0.05% to 0.40% C defining a carburizing steel or greater than 0.40% to 1.

Abstract: Coil winding method for steel bars providing, at the outlet of the rolling mill (2), cooling stages by means of WB (4?, 4?, 4??) and equallsation in air so as to perform “soft” hardening on the bar which generates a microstructure consisting, on the surface, of martensite and bainite and, in the center, of ferrite and pearlite, and winding of the bar in the form of a compact coil by means of a coil winder (5). In the position wound on the coil, the bar cools slowly with tempering of the bainite and martensite formed on the surface. This is followed by a straightening stage, jo performed during the coil unwinding phase, and a natural ageing stage, maintaining the bar at ambient temperature.

Abstract: The invention provides a method of fabricating a steel part, the method comprising the steps of: preparing and casting a steel having the following composition in percentage by weight: 0.06%?C?0.25%; 0.5%?Mn?2%; traces?Si?3%; traces?Ni?4.5%; traces?Al?3%; traces?Cr?1.2%; traces?Mo?0.30%; traces?V?2%; traces?Cu?3.5%; and satisfying at least one of the following conditions: 0.5%?Cu?3.5%; 0.5%?V?2%: 2?Ni?4.5% and 1%?Al?2%; ?the remainder being iron and impurities resulting from preparation; hot deforming the cast steel at least once at a temperature in the range 1100° C. to 1300° C. in order to obtain a blank of the part; controlled cooling of the blank for the part in still air or forced air; and heating the steel to perform precipitation annealing before or after machining the part from said blank. The invention also provides a part obtained by the method.

Abstract: A hot worked low alloy tool steel plate can be machined into mold base parts useful for holding tooling used in plastic injection molding. The tool steel alloy preferably exhibits desired strength, toughness, ductility, weldability, uniform hardness and dimensional stability. A process for manufacture of the steel plate includes hot working, hot roller leveling, air cooling and tempering to desired hardness.

Abstract: A high-strength forged part is disclosed which comprises a base phase structure, comprising 30% or more of ferrite in terms of a space factor, and a second phase structure, comprising bainite and/or martensite, and retained austenite having an average grain diameter of 5 ?m or less and a content represented by 50×[C]<[V?R]<150×[C], wherein [V?R] represents a space factor of the retained austenite (?R) and [C] represents the mass % of C in the forged part. Furthermore, a high-strength forged part is disclosed which comprises a base phase structure, comprising 50% or more of tempered bainite or tempered martensite in terms of a space factor, and a second phase structure, comprising martensite and 3% to 30% retained austenite in terms of a space factor, wherein the portion of the retained austenite and martensite having an aspect ratio of 2 or less is 25% or less in terms of a space factor.

Abstract: A method of manufacturing a clutch housing having a boss portion and a drum portion integrally provided with the boss portion, is characterized by steps of integrally forming the boss portion and the drum portion by hot forging, and forced-cooling at least a portion of the boss portion, continuous to the integrally forming step.

Abstract: 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.

Abstract: A flat rolled, high strength, formable steel product has a yield strength of at least about 100 ksi. The product has sufficient formability such that it can withstand a longitudinal or transverse 180° bend of less than 1.0 times its thickness and is preferably comprised of a high strength, low alloy steel composition containing a vanadium-nitride microalloy. The steel product is preferably produced by cold rolling a first steel product having a yield strength of at least about 70 ksi and a n-value from about 0.1 to about 0.16. Cold rolling of the first steel product reduces its thickness and increases its yield strength to at least 100 ksi.

Abstract: A high strength steel sheet having (2-1) a base phase structure, the base phase structure being tempered martensite or tempered bainite and accounting for 50% or more in terms of a space factor relative to the whole structure, or the base phase structure comprising tempered martensite or tempered bainite which accounts for 15% or more in terms of a space factor relative to the whole structure and further comprising ferrite, the tempered martensite or the tempered bainite having a hardness which satisfies the relation of Vickers hardness (Hv)?500[C]+30[Si]+3[Mn]+50 where [ ] represents the content (mass %) of each element, and (2-2) a second phase structure comprising retained austenite which accounts for 3 to 30% in terms of a space factor relative to the whole structure and optionally further comprising bainite and/or martensite, the retained austenite having a C concentration (C?R) of 0.8% or more.

Abstract: A method for processing a hot formed, high-tensile-strength steel having an ultimate tensile strength (UTS) of at least about 730 MPa (105 ksi) and excellent toughness to retain essentially all the strength and toughness is provided. This processing is needed for the fabrication of high strength fittings that are used in the construction of linepipe for transport of natural gas, crude oil, as well as other applications. Furthermore, the hot formed high strength steel may be weldable with a Pcm of less than or equal to 0.35.

Abstract: There are proposed a track link production method capable of providing markedly improved wear life with good cost performance and a track link produced by this method. To this end, the track link production method includes a heat treatment process (Steps 4, 5) of applying quenching and low temperature tempering treatment to a whole link material after hot forging (Step 2), and is designed such that desired machining is applied to the link material (Step 3) before the heat treatment process (Steps 4, 5) and such that after the heat treatment process (Steps 4, 5), tempering (Step 6) and finish machining (Step 7) are sequentially applied to some of the parts which have undergone the machining process, the some parts including at least parts where high dimensional accuracy is required.

Abstract: A high-strength steel sheet comprises carbon: 0.06 to 0.25 mass %, Si: 0.5 to 3.5 mass % and Mn: 0.7 to 4 mass %. Its mother structure is ferrite, its second phase structure comprises martensite and the residual austenite and the second phase structure measured by image analysis has an area fraction of 25% or less based on the total structure. The steel sheet satisfies the following requirements (1) to (3): (1) the volume fraction (Vt?hd R) of the residual austenite is 5% or more; (2) the ratio (SF?R/Vt?R) of the area fraction (SF?R) of the residual austenite within ferrite to Vt?R is 0.65 or more; and (3) the ratio [?2/(?1+?R)] of the space factor (?2) of martensite to the second phase structure (?1+?R) is 0.25 to 0.60. The steel sheet has excellent balance between strength and local elongation, and a low yield ratio.

Abstract: A method of manufacturing a high strength steel sheet containing, in mass %, C: 0.02 to 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%. The method includes performing hot rough rolling either directly or after heating to a temperature of at most 1300° C., commencing hot finish rolling either directly or after reheating or holding, completing finish rolling at a temperature of at least 780° C., performing coiling after cooling to a temperature of 750° C. or below at an average cooling rate of at least 3° C./second, heating to an annealing temperature of at least 700° C. and then cooling to a temperature of 600° C. or below at an average cooling rate of at least 3° C./second, then holding in a temperature range of 450-600° C. for at least 10 seconds, and performing hot dip galvanizing after cooling.

Abstract: A weldable structural steel product having TiN and ZrN precipitates, which contains, in terms of percent by weight, 0.03 to 0.17% C, 0.01 to 0.5% Si, 0.4 to 2.0% Mn, 0.005 to 0.2% Ti, 0.0005 to 0.1% Al, 0.001 to 0.03% Zr, 0.008 to 0.030% N, 0.0003 to 0.01% B, 0.001 to 0.2% W, at most 0.03% P, at most 0.03% S, at most 0.01% O, and balance Fe and incidental impurities while satisfying conditions of 1.2?Ti/N?2.5, 0.3?Zr/N?2.0, 10?N/B?40, 2.5?Al/N?7, and 6.8?(Ti+Zr+2Al+4B)/N?17, and having a microstructure essentially consisting of a complex structure of ferrite and pearlite having a grain size of 20 ?m or less.

Abstract: A ferritic steel sheet wherein a mean value of X-ray random intensity ratios of a group of {100}<011> to {223}<110> orientations is 3.0 or more and a mean value of X-ray random intensity ratios of three crystal orientations of {554}<225>, {111}<112>, and {111}<110> is 3.5 or less and further at least one of the r values in a rolling direction and a direction at a right angle of that is 0.7 or less.

Abstract: A steel material and a steel pipe made by using the same are provided which are to be used in severe oil well environments. Such a highly tough oil well steel pipe can be produced by rolling the base material, quenching the rolling product from the austenite region and tempering the same so that the relationship between the content of Mo [Mo] in the carbides precipitated at austenite grain boundaries and the austenite grain size (according to ASTM E 112) can be defined by the formula (a) given below. In this manner, steel pipes suited for use even under oil well environments becoming more and more severe can be produced while satisfying the requirements that the cost should be rationalized, the productivity improved and energy saved.

Abstract: A weldable structural steel product having fine complex precipitates of TiN and MnS is provided which contains, in terms of percent by weight, 0.03 to 0.17% C, 0.01 to 0.05% Si, 1.0 to 2.5% Mn, 0.05 to 0.2% Ti, 0.0005 to 0.1% Al, 0.008 to 0.030% N, 0.0003 to 0.01% B, 0.001 to 0.2% W, at most 0.03% P, 0.003 to 0.05% S, at most 0.005% O, and balance Fe and incidental impurities while satisfying conditions of 1.2?Ti/N?2.5, 10?N/B?40, 2.5?Al/N?7, 6.5?(Ti+2Al+4B)/N?14, and 220?Mn/S?400. The steel has a microstructure consisting essentially of a complex structure of ferrite and pearlite having a grain size of 20 ?m or less.

Abstract: In a method of making a hardened sheet metal article, at least one pot-shaped depression is formed in a sheet metal blank. Thereafter, the sheet metal blank is hot formed in a press mold to a sheet metal article, and the sheet metal article is hardened. The press mold provides hereby a calibration of the depression to provide the final shape.

Abstract: A method of post-solidification processing to minimize the content of extremely coarse grain-refining precipitates that may form during solidification is low-alloy and alloy high-strength steels containing approximately 0.09-0.17% by weight C so as to provide improved toughness in a wrought and heat-treated product. The method entails cooling an as-cast steel at a reduced rate in a furnace held at a temperature in excess of the equilibrium solution temperature for AlN in austenite. The steel is maintained at this temperature for a sufficient amount of time to effect the dissolution of coarse AlN precipitates in the microstructure, and the so-treated steel is then cooled at any desired rate to room temperature or to a hot-rolling temperature.

Abstract: The invention relates to a method for producing hot strip which features good forming ability and increased strength. This is achieved in that a hot strip (W) which is produced in particular from continuous casting in the shape of reheated slabs or slabs obtained directly from the casting heat, from thin slabs or cast strip, based on a steel comprising (in mass %) C: 0.001-1.05%; Si: ?1.5%; Mn: 0.05-3.5%; Al: ?2.

Abstract: The present invention provides a high-strength thin steel sheet drawable and excellent in a shape fixation property and a method of producing the same. For the steel sheet, on a plane at the center of the thickness of a steel sheet, the average ratio of the X-ray strength in the orientation component group of {100}<011> to {223}<110> to random X-ray diffraction strength is 2 or more and the average ratio of the X-ray strength in three orientation components of {554}<225>, {111}<112> and {111}<110> to random X-ray diffraction strength is 4 or less. The arithmetic average of the roughness Ra of at least one of the surfaces is 1 to 3.5 &mgr;m; the surfaces of the steel sheet are covered with a composition having a lubricating effect; and the friction coefficient of the steel sheet surfaces at 0 to 200° C. is 0.05 to 0.2.

Abstract: According to the invention, a high-strength hot rolled steel sheet having an excellent shape fixability as hot-rolled and an excellent fatigue durability after the forming, excellent weldability and phosphatability and a tensile strength of not less than 590 MPa level can be obtained by comprising C: not less than 0.02 mass % but not more than 0.2 mass %, Si: not less than 0.5 mass % but not more than 2.0 mass %, Mn: not less than 1.0 mass % but not more than 3.0 mass %, Al: not less than 0.01 mass % but not more than 0.1 mass %, N: not less than 0.002 mass % but not more than 0.006 mass %, P: not more than 0.03 mass %, S: not more than 0.01 mass % and solid-soluted (C+N): not less than 0.

Abstract: A steel sheet composition contains appropriate amounts of C, Si, Mn, P, S, Al and N and 0.5 to 3.0% Cu. A composite structure of the steel sheet has a ferrite phase or a ferrite phase and a tempered martensite phase as a primary phase, and a secondary phase containing retained austenite in a volume ratio of not less than 1%. In place of the Cu, at least one of Mo, Cr, and W may be contained in a total amount of not more than 2.0%. This composition is useful in production of a high-ductility hot-rolled steel sheet, a high-ductility cold-rolled steel sheet and a high-ductility hot-dip galvanized steel sheet having excellent press formability and excellent stain age hardenability as represented by a &Dgr;TS of not less than 80 MPa, in which the tensile strength increases remarkably through a heat treatment at a relatively low temperature after press forming.

Abstract: A method for manufacturing a steel sheet comprising continuously casting a steel containing 0.04 to 0.2 wt. % C, 0.25 to 2 wt. % Si, 0.5 to 2.5 wt. % Mn, and 0.1 wt. % or less Al to form a slab; hot-rolling by rough-rolling the slab to form a sheet bar and finish-rolling the sheet bar with a reduction in thickness at the final stand of less than 30%, the finish-rolling being completed at a temperature from the Ar3 transformation point to the Ar3 transformation point +60° C.; primary-cooling the hot-rolled steel sheet, the primary cooling being started within 1 second after the completion of hot-rolling and conducting the cooling at a cooling speed of higher than 200° C./sec down to a temperature of Ar3 −30° C. to the Ar1 transformation point; slow cooling or air-cooling the primary-cooled steel sheet at a temperature of the Ar3 transformation point to the Ar1 transformation point at 10° C.

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: Dual phase steel sheet is made using a time/temperature cycle including a soak at about 1340-1425F and a hold at 850-920F, where the steel has the composition in weight percent, carbon: 0.02-0.20; aluminum: 0.010-0.150; titanium: 0.01 max; silicon: 0.5 max; phosphorous: 0.060 max; sulfur: 0.030 max; manganese: 1.5-2.40; chromium: 0.03-1.50; molybdenum: 0.03-1.50; with the provisos that the amounts of manganese, chromium and molybdenum have the relationship: Mn+6Cr+10Mo)=at least 3.5%. The sheet is preferably in the form of a strip treated in a continuous galvanizing or galvannealing line, and the product is predominantly ferrite and martensite.

Abstract: An apparatus for cooling a hot rolled steel strip comprising a transfer means arranged behind a final finishing mill, the transfer means comprising a plurality of transfer rolls for transferring the steel strip; at least one upper surface cooling means arranged at an upper surface side of the transfer means for cooling the steel strip by ejecting cooling water to an upper surface of the steel strip, the upper surface cooling means being capable of moving freely up and down and having a water breaking means at least at an outlet side of the cooling apparatus and at a position corresponding to the transfer rolls; and at least one lower surface cooling means arranged at a lower surface side of the transfer means relative to the upper surface cooling means and the steel strip to be transferred, for cooling the hot strip by ejecting cooling water at a lower surface of the steel strip.

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: Disclosed is a welding structural steel product exhibiting a superior heat affected zone toughness, comprising, in terms of percent by weight, 0.03 to 0.17% C, 0.01 to 0.5% Si, 0.4 to 2.0% Mn, 0.005 to 0.2% Ti, 0.0005 to 0.1% Al, 0.008 to 0.030% N, 0.0003 to 0.01% B, 0.001 to 0.2% W, at most 0.03% P, at most 0.03% S, at most 0.005% O, and balance Fe and incidental impurities while satisfying conditions of 1.2≦Ti/N≦2.5, 10≦N/B≦40, 2.5≦Al/N≦7, and 6.5≦(Ti+2Al+4B)/N≦14, and having a microstructure essentially consisting of a complex structure of ferrite and pearlite having a grain size of 20 &mgr;m or less.

Abstract: The objective of the present invention is to provide a forging method that improves workability in machining, by turning the metallographical structure of products subject to impact load to a fine ferrite-perlite structure, without adopting the method of quenching and tempering, to obtain, as strength, a yield point (YP value) exceeding that obtained by the method of quenching and tempering, and making the tensile strength (TS) smaller compared with the method of quenching and tempering. A material to be forged has at least one kind of group 5 metal added thereto and is heated to a temperature suitable for hot forging. After forging to prescribed shape, cooling, and holding for a prescribed set time in a furnace at a tempering temperature, the material is further cooled to normal temperature by natural cooling.

Abstract: The invention relates to a higher-strength steel strip or steel sheet comprising a predominantly ferritic-martensitic microstructure with a martensite content of between 4 and 20%, wherein the steel strip or steel sheet, apart from Fe and impurities due to smelting, comprises (in % by weight) 0.05-0.2% C, ≦1.0% Si, 0.8-2.0% Mn, ≦0.1% P, ≦0.015% S, 0.02-0.4% Al, ≦0.005% N, 0.25-1.0% Cr, 0.002-0.01% B. Preferably the martensite content is approximately 5% to 20% of the predominantly martensitic-ferritic microstructure. Such a higher-strength steel strip or steel sheet made from a dual phase steel comprises good mechanical/technological properties even after being subjected to an annealing process which includes an overageing treatment. Furthermore, the invention relates to a method for producing steel strip or steel sheet according to the invention.

Abstract: A method of producing ultra-fine grain structure for an unalloyed or low-alloyed steel is characterized in that it includes as a combination steps wherein the steel is heated (1, 2) to a temperature (T1) above Ac3 temperature for transforming the structure thereof completely austenitic whereby both temperature level (T1) and holding time (d1) at the temperature (T1) are restricted for hindering austenitic grain growth, the steel is cooled (3) without any deformation below Tnr temperature, rolling (4a, 4b) is started below Tnr temperature and is continued within the temperature range between Tnr and Ac3 in which the structure of the steel is essentially austenitic but with no recrystallization of austenite, and the steel is cooled further (5) below Ar3 and Ar1 temperatures. The method of the invention is suitable to be used at the final storage of production, especially, for improving some properties, like hardness, tensile strength and impact toughness, of a steel.