Abstract: This wear-resistant steel plate includes, in terms of mass %, C: not less than 0.13% and not more than 0.18%, Si: not less than 0.5% but less than 1.0%, Mn: not less than 0.2% and not more than 0.8%, P: not more than 0.020%, S: not more than 0.010%, Cr: not less than 0.5% and not more than 2.0%, Mo: not less than 0.03% and not more than 0.30%, Nb: more than 0.03% but not more than 0.10%, Al: not less than 0.01% and not more than 0.20%, B: not less than 0.0005% and not more than 0.0030%, and N: not more than 0.010%, with a remainder being Fe and unavoidable impurities, wherein an element composition is such that HI is 0.7 or greater and Ceq exceeds 0.50, and an HB value (Brinell hardness) at 25° C. is not less than 360 and not more than 440.

Abstract: The present invention, among other things, relates to a method for producing a workpiece by press hardening a semi-finished product, which is distinguished by the fact that the semi-finished product consists of a steel which has a high content of silicon of at least 0.9 wt. %, with a simultaneously small content of manganese of less than 0.9 wt. %, a small carbon content of less than 0.25 wt. %, and a high chromium content of more than 1.20 wt. %, and which by heating is brought to a state in which the structure of the steel that is used is at least partially transformed to austenite, also optionally fully transformed to austenite, and the thus-heated semi-finished product is hot shaped so that after the hot deformation shaping, a structure is present in the workpiece that has a complex phase structure with predominantly martensite and ferrite fractions. In addition, a workpiece is described, which is produced according to this method, as well as uses of such a workpiece.

Abstract: The ultrahigh-strength steel sheet contains, in mass %, C: 0.05-0.25%, Si: 1.00-2.5%, Mn: 2.0-4.0%, P: 0.1% or below (not inclusive of 0%), S: 0.05% or below (not inclusive of 0%), Al: 0.01-0.15%, Ti: 0.003-0.10%, N: 0.01% or below (not inclusive of 0%), the balance comprising iron with inevitable impurities, and is a composite structure steel sheet comprising 10-50 area % ferrite and 50 area % or above martensite, in which the average circle-equivalent grain diameter of ferrite grains is 2.0 ?m or below, the average aspect ratio of ferrite grains is 2.0 or below, and the tensile strength is 1,100 MPa or above. Accordingly, the ultrahigh-strength steel sheet is excellent in hydrogen embrittlement resistance and workability.

Abstract: A high-strength hot-dip galvanized steel sheet that even on the premise of ordinary CGL heat cycle, has a low yield stress and excels in resistance to natural aging and baking hardenability without reliance on the use of expensive Mo; and a process for producing the same. The constituent composition thereof comprises 0.01 to less than 0.08% C, 0.2% or less Si, more than 1.0 to 1.8% Mn, 0.10% or less P, 0.03% or less S, 0.1% or less Al, 0.008% or less N and more than 0.5% Cr so that the relationship 1.95?Mn(mass %)+1.3Cr(mass %)?2.8 is satisfied and comprising the balance iron and unavoidable impurities. The structure thereof has a ferrite phase and a martensite phase of 2 to 15% area ratio, and the cumulative area ratio of pearlite phase and/or bainite phase is 1.0% or less. In the production of this hot-dip galvanized steel sheet, the temperature and cooling rate are controlled during the annealing/plating operation subsequent to cold rolling.

Abstract: A high tensile-strength galvanized steel sheet includes C: at least 0.05% but less than 0.12%, Si: at least 0.01% but less than 0.35%, Mn: 2.0% to 3.5%, P: 0.001% to 0.020%, S: 0.0001% to 0.0030%, Al: 0.005% to 0.1%, N: 0.0001% to 0.0060%, Cr: more than 0.5% but not more than 2.0%, Mo: 0.01% to 0.50%, Ti: 0.010% to 0.080%, Nb: 0.010% to 0.080%, and B: 0.0001% to 0.0030%, the remainder being Fe and unavoidable impurities, wherein the high tensile-strength galvanized steel sheet has a microstructure that contains 20% to 70% by volume ferrite having an average grain size of 5 ?m or less. The high tensile-strength galvanized steel sheet has a tensile strength of at least 980 MPa, and excellent formability and weldability.

Abstract: The steel according to the invention is characterized in that, in order to keep its weight content of molybdenum below 0.45%, its chemical composition, besides the iron and the inevitable residual impurities that result from the smelting of the steel, corresponds to the following analysis, given as percentages by weight: 0.3?C %?0.5 0.20?Mo %<0.45 0.4?Mn %?1.0 0.4?Cr %?2.0 0.04?Ni %?0.8 0.02?Nb %?0.045 0.03?V %?0.30 0.02?Ti %?0.05, with Ti>3.5 N 0.003?B %?0.005% S %?0.015 P %?0.015, and optionally 0.05?Si %?0.20; Al %?0.05 and N %?0.015. By cold forming a hot-rolled wire rod resulting from continuous casting, it is possible to obtain, after heat treatment, “ready-to-use” coined parts, such as cap screws for example for the automotive industry, that offer a tensile strength from 1200 to more than 1500 MPa while having a good hydrogen embrittlement resistance, and this with a specially controlled “raw material” production cost.

Abstract: The present invention inexpensively provides with high productivity and good yield a steel rod superior in drawability and a steel wire superior in twistability using the same as a material, that is, draws a high strength steel rod superior in ductility where the chemical components contain C: 0.80 to 1.20%, Si: 0.1 to 1.5%, Mn: 0.1 to 1.0%, Al: 0.01% or less, Ti: 0.01% or less, one or both of W: 0.005 to 0.2% and Mo: 0.003 to 0.

Abstract: The invention provides a steel pipe excellent in deformation characteristics, most notably a steel pipe for expandable-pipe oil well and a low-yield-ratio line pipe, and a method of producing the same without conducting water cooling requiring large-scale heat treatment equipment, namely a method of producing a steel pipe excellent in deformation characteristics whose microstructure is a two-phase structure including a martensite-austenite constituent at an area fraction of 2 to 10% and a soft phase, which method comprises: heating at Ac1+10° C. to Ac1+60° C. and thereafter cooling a precursor steel pipe which contains, in mass %, C: 0.04 to 0.10% and Mn: 1.00 to 2.50%, is limited to Si: 0.80% or less, P: 0.03% or less, S: 0.01% or less, Al: 0.10% or less and N: 0.01% or less, further contains one or more of Ni: 1.00% or less, Mo: 0.60% or less, Cr: 1.00% or less and Cu: 1.00% or less, where content of Mn and content of one or more of Cr, Ni, Mo and Cu satisfy Mn+Cr+Ni+2Mo+Cu?2.

Abstract: A steel sheet undergone precipitation strengthening and refinement in crystal grain size by containing at least one element of 0.005% to 0.05% of Nb, 0.005% to 0.05% of Ti, and 0.0005% to 0.005% of B as a chemical composition is produced through continuous annealing. A steel containing at least one element of Nb, Ti, and B is hot rolled, cooled at a cooling rate of 40° C./s or less, and coiled at 550° C. or higher to facilitate precipitation of cementite after recrystallization annealing. As a result, a steel sheet for a can having a tensile strength of 450 to 550 MPa, a total elongation of 20% or more, and a yield elongation of 5% or less is produced.

Abstract: A method for producing a plate of steel which is resistant to abrasion and whose chemical composition includes, by weight: 0.24%?C<0.35%; 0%?Si?2%; 0%?Al?2%; 0.5%?Si+Al?2%; 0%?Mn?2.5% 0%?Ni?5%; 0%?Cr?<5% 0%?Mo?1%; 0%?W?2%; 0.1%?Mo+W/2?1%; 0%?B?0.02%; 0%?Ti?1.1%; 0%?Zr?2.2%; 0.35%<Ti+Zr/2?1.1%; 0%?S?0.15%; N<0.03%, optionally up to 1.5% of copper; optionally at least one element selected from Nb, Ta and V at contents such that Nb/2 +Ta/4+V?0.5%; optionally at least one element selected from among Se, Te, Ca, Bi, Pb at contents which are less than or equal to 0.1%; and the balance being iron and impurities resulting from the production operation. The chemical composition further complying with the following relationships: C*=C?Ti/4?Zr/8+7×N/8?0.095% and 1.05×Mn+0.54×Ni+0.50×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%.

Abstract: This hot rolled steel contains, in terms of mass %, C: 0.01 to 0.1%, Si: 0.01 to 0.1%, Mn: 0.1 to 3%, P: not more than 0.1%, S: not more than 0.03%, Al: 0.001 to 1%, N: not more than 0.01%, Nb: 0.005 to 0.08%, and Ti: 0.001 to 0.2%, with a remainder being iron and unavoidable impurities, wherein a formula: [Nb]×[C]?4.34×10?3 is satisfied, a grain boundary density of solid solution C is not less than 1 atom/nm2 and not more than 4.5 atoms/nm2, and a grain size of cementite grains precipitated at grain boundaries within the steel sheet is not more than 1 um. This method for manufacturing a hot rolled steel sheet includes: heating a steel slab having the same composition as the above hot rolled steel sheet at a temperature that is not less than a temperature of SRTmin (° C.) and not more than 1,170° C.; performing rough rolling at a finishing temperature of not less than 1,080° C. and not more than 1,150° C.

Abstract: A high strength cold-rolled steel sheet and a high strength plated steel sheet which have an excellent surface appearance required for outer panels of automobiles and which have an extremely high r value in a direction at 45° with respect to the rolling direction and which have excellent press formability and a tensile strength of at least 340 MPa and a process for their manufacture are provided. The steel sheets have a chemical composition consisting essentially of, in mass %, C: 0.0005-0.025%, Si: at most 0.2%, Mn: 0.3-2.5%, P: at most 0.15%, S: at most 0.02%, N: at most 0.006%, sol. Al: less than 0.005%, Ti: 0.005-0.05%, and Nb: 0.020-0.200% with the mass ratio (Nb/Ti) of the contents of Nb and Ti being at least 2, and a remainder of Fe and impurities, and they have an r value in a direction at 45° with respect to the rolling direction (r45) of at least 1.80 and/or a mean r value (0 of at least 1.60, and a tensile strength of at least 340 MPa.

Abstract: The present invention provides high strength hot rolled steel plate for line-pipes superior in low temperature toughness, and a method of production of the same, containing, by mass %, C: 0.01 to 0.1%, Si: 0.05 to 0.5%, Mn: 1 to 2%, P: ?0.03%, S: ?0.005%, O: ?0.003%, Al: 0.005 to 0.05%, N: 0.0015 to 0.006%, Nb: 0.005 to 0.08%, and Ti: 0.005 to 0.02%, where N?14/48×Ti>0% and Nb—93/14×(N?14/48×Ti)>0.005%, and a balance of Fe and unavoidable impurities, said steel plate characterized in that its microstructure is a continuously cooled transformed structure, a reflected X-ray intensity ratio {211}/{111} of the {211} plane and {111} plane parallel to the plate surface in the texture at the center of plate thickness is 1.1 or more, and an in-grain precipitate density of the precipitates of Nb and/or Ti carbonitrides is 1017 to 1018/cm3.

Abstract: A steel pipe with excellent expandability, comprises, by mass %, C: 0.1 to 0.45%, Si: 0.3 to 3.5%, Mn: 0.5 to 5%, P: less than or equal to 0.03%, S: less than or equal to 0.01%, soluble Al: 0.01 to 0.8% (more than or equal to 0.1% in case Si content is less than 1.5%), N: less than or equal to 0.05%, O: less than or equal to 0.01%, and balance being Fe and impurities, having a mixed microstructure comprising ferrite and one or more selected from fine pearlite, bainite and martensite, and has a tensile strength of more than or equal to 600 MPa and a uniform elongation satisfying the following formula u-el?28?0.0075 TS, wherein u-el is uniform elongation (%) and TS is tensile strength (MPa).

Abstract: The present invention provides an abrasion resistant steel having a hardness of HB400 to HB520, having little change of hardness during long term use, and superior in toughness, characterized by containing, by mass %, C: 0.21% to 0.30%, Si: 0.30 to 1.00%, Mn: 0.32 to 0.70%, P: 0.02% or less, S: 0.01% or less, Cr: 0.1 to 2.0%, Mo: 0.1 to 1.0%, B: 0.0003 to 0.0030%, Al: 0.01 to 0.1%, and N: 0.01% or less, further containing one or more of V: 0.01 to 0.1%, Nb: 0.005 to 0.05%, Ti: 0.005 to 0.03%, Ca: 0.0005 to 0.05%, Mg: 0.0005 to 0.05%, and REM: 0.001 to 0.

Abstract: The present invention provides hot rolled steel plate for spiral pipe superior in low temperature toughness, thick in gauge, for example, having a plate thickness of 14 mm or more, and having a high strength of the API-X65 standard or more spiral pipe and a method of production of the same, that is, steel plate containing, by mass %, C: 0.01 to 0.1%, Si: 0.05 to 0.5%, Mn: 1 to 2%, P?0.03%, S?0.005%, O?0.003%, Al: 0.005 to 0.05%, N: 0.0015 to 0.006%, Nb: 0.005 to 0.08%, Ti: 0.005 to 0.02%, N?14/48×Ti>0%, Nb?93/14×(N?14/48×Ti>0.005%, Mo: 0.01% to less than 0.1%, Cr: 0.01 to 0.3%, and Cu: 0.01 to 0.3%, and having a balance of Fe and unavoidable impurities, characterized in that an elongation rate of a microstructure unit in a cross-section in the pipe circumferential direction after pipemaking is 2 or less.

Abstract: A case hardening steel tube which has a hardness of 72-80 HRB and which gives a carburized layer with a high strength and high wear resistance and adequate resistance to impact fracture when it is formed into a final product by working and subsequent carburizing and quenching under relatively mild conditions is manufactured by forming a tube from a steel having a steel composition comprising, in mass percent, C: 0.1-0.25%, Si: 0.2-0.4%, Mn: 0.3-0.9%, P: at most 0.02%, S: 0.001-0.15%, Cr: 0.5-0.9%, Mo: 0.15-1%, Al: 0.01-0.1%, B: 0.0005-0.009%, N: less than 0.006%, and a remainder essentially of Fe, then subjecting the resulting steel tube to normalizing by soaking at a temperature of 880-980° C. followed by cooling at a cooling rate of at most 70° C. per minute, carrying out cold working of the normalized steel tube, and then annealing the cold worked steel tube at a temperature of 700-820° C.

Abstract: Low alloy steel for oil country tubular goods contains, in percentage by mass, 0.20% to 0.35% C, 0.05% to 0.5% Si, 0.05% to 0.6% Mn, at most 0.025% P, at most 0.01% S, 0.005% to 0.100% Al, 0.8% to 3.0% Mo, 0.05% to 0.25% V, 0.0001% to 0.005% B, at most 0.01% N, and at most 0.01% O, the balance comprising Fe and impurities, the steel satisfying Expression (1): 12V+1?Mo?0 (1) where the symbols of elements represent the contents of the elements in percentage by mass. In this way, the steel according to the present invention has high SSC resistance.

Abstract: A galvanized steel sheet having (a) a dual phase microstructure with a martensite phase and a ferrite phase and (b) a composition containing by percent weight: carbon in a range from about 0.01% to about 0.18%; manganese in a range from about 0.2% to about 3%; silicon ?about 1.2%; aluminum in a range from about 0.01% to about 0.1%; one or both of chromium and nickel in a range from about 0.1% to about 3.5%; calcium in a range from about 0.0003% to about 0.01%; phosphorus ?about 0.01%; sulfur ?about 0.03%; nitrogen ?about 0.02%; molybdenum ?about 1%; copper ?about 0.8%; one or more of niobium, titanium, and vanadium ?about 1%; and boron ?about 0.006% by weight; and with the balance of the composition being iron and incidental ingredients. In one embodiment, the steel sheet is both galvanized and galvannealed.

Abstract: An alloy composition of FeaBbSicPxCyCuz. Parameters meet the following conditions: 79?a?86 atomic %; 5?b?13 atomic %; 0?c?8 atomic %; 1?x?8 atomic %; 0?y?5 atomic %, 0.4?z?1.4 atomic %; and 0.08?z/x?0.8. Or, parameters meet the following conditions: 81?a?86 atomic %; 6?b?10 atomic %; 2?c?8 atomic %; 2?x?5 atomic %; 0?y?4 atomic %; 0.4?z?1.4 atomic %, and 0.08?z/x?0.8.

Abstract: Disclosed is a high-strength steel sheet which has a predetermined component composition, structurally has a ferrite matrix structure and bainitic and martensitic second phase structures, and has a ferrite fraction of from 50 to 86 percent by area, a bainite fraction of from 10 to 30 percent by area, and a martensite fraction of from 4 to 20 percent by area, relative to the entire structure, in which the bainite area fraction is larger than the martensite area fraction, the ferrite has an average grain size of 2.0 to 5.0 ?m, and the ratio of the average ferrite hardness (Hv) to the tensile strength (MPa) of the steel sheet is equal to or more than 0.25. The steel sheet excels both in TS-EL balance and TS-? balance at high strengths on the order of 590 to 780 MPa.

Abstract: An exemplary hot rolled steel sheet can included, in terms of percent by mass, C of 0.01 to 0.2%; Si of 0.01 to 2%; Mn of 0.1 to 2%; P of ?0.1%; S of ?0.03%; Al of 0.001 to 0.1%; N of ? 0.01%; and as a remainder, Fe and unavoidable impurities. For example, a microstructure can be substantially a homogeneous continuous-cooled microstructure, and an average grain size of the microstructure may be more than 8 ?m and 30 ?m or less. An exemplary method for manufacturing a hot rolled steel sheet can include subjecting a slab having the above composition to a rough rolling so as to obtain a rough rolled bar, subjecting the rough rolled bar to a finish rolling so as to obtain a rolled steel under conditions in which a finishing temperature is (Ar3 transformation point +50° C.) or more; and starting cooling the rolled steel after 0.5 seconds or more pass from the end of the finish rolling at a temperature of the Ar3 transformation point or more.

Abstract: The invention provides a Martensite wear-resistant cast steel with film Austenite for enhancement of toughness comprises 0.25˜0.34 wt % C, 1.40˜2.05 wt % Si, 0.90˜1.20 wt % Mn, 1.80˜2.50 wt % Cr, 0.0005˜0.005 wt % B, 0.01˜0.06 wt % Ti, 0.015˜0.08 wt % Rare Earth, 0.015˜0.06 wt % Al, less than 0.035 wt % S, less than 0.035 wt % P, and the balance of iron. The method of producing the cast steel includes smelting and heat-treatment, after smelting as normal operation, adding Ferro-Rare Earth and Ferro-Boron in the ladle in sequence, then high temperature normalizing, water quenching and low temperature tempering. TEM structure of the cast steel is martensite lath with film austenite between martensite laths. Cast steel of the invention exhibits high hardenability and toughness, and low cost without precious Molybdenum and Nickel, applied to a range of wear-resistant castings, especially to heavy-section castings, i.e. heavy-section tooth.

Abstract: A steel bar for a steering rack that contains 0.50 to 0.60% by mass of C, 0.05 to 0.5% by mass of Si, 0.2 to 1.5% by mass of Mn, 0.0005 to 0.003% by mass of B, 0.005 to 0.05% by mass of Ti, 0.0005 to 0.1% by mass of Al, and 0.002 to 0.02% by mass of N is provided. Given D as a diameter of the steel bar, then the steel bar is adjusted in such a manner that quenched and tempered structures in a portion of the steel bar at a depth of D/4 from a surface satisfy conditions I), II), and III) as follows: I) a sum of a tempered bainitic structure and a tempered martensitic structure accounts for 30 to 100% in area percentage; II) a regenerated perlite structure accounts for 0 to 50% in area percentage; and III) a sum of the tempered bainitic structure, the tempered martensitic structure, and the regenerated perlite structure accounts for 50 to 100% in area percentage.

Abstract: The present invention provides a steel plate having a low welding crack susceptibility and a yield strength of 800 MPa and a manufacturing method for the same. The steel plate having a low welding crack susceptibility comprises the following chemical components (wt. %: percent by weight): C: 0.03-0.08 wt. %, Si: 0.05-0.70 wt. %, Mn: 1.30-2.20 w.t %, Mo: 0.10-0.30 wt. %, Nb: 0.03-0.10 wt. %, V: 0.03-0.45 wt. %, Ti: 0.002-0.040 wt. %, Al: 0.02-0.04 wt. %, B: 0.0010-0.0020 wt. %, the balance being Fe and unavoidable impurities, and the welding crack susceptibility index meets the following formula: Pcm?0.20%. The thermo-mechanical controlled rolling and cooling processes is used to obtain an ultrafine bainite batten matrix structure, which increases the intensity, plasticity and toughness of the steel plate. The steel plate with a low welding crack susceptibility of the present invention has a yield strength of greater than 800 MPa, a tensile strength of greater than 900 MPa, a Charpy impact energy Akv (?20° C.

Abstract: High tensile strength steels that have both favorable delayed fracture resistance and a tensile strength of 600 MPa or higher and are suitably used in construction machinery, tanks, penstocks, and pipelines, as well as methods for manufacturing such steels are provided. The safety index of delayed fracture resistance (%) is 100×(X1/X0), where X0: reduction of area of a specimen substantially free from diffusible hydrogen, and X1: reduction of area of a specimen containing diffusible hydrogen.

Abstract: According to an exemplary embodiment of the present invention, a bake-hardening hot-rolled steel sheet with excellent workability can be provided. The exemplary steel sheet can contain, in terms of mass %, C of about 0.01 to 0.2%, Si of about 0.01 to 2%, Mn of about 0.1 to 2%, P of about 0.1% or less, S of about 0.03% or less, Al of about 0.001 to 0.1%, N of about 0.01% or less, Nb of about 0.005 to 0.05%, and as the remainder, Fe and unavoidable impurities. A microstructure of the steel sheet can be a polygonal ferrite and/or a continuous-cooled microstructure having an average particle diameter of about 2 ?m to 8 ?m, and the grain boundary abundance ratio of solute C and/or solute N may be about 0.28 or lower. An exemplary embodiment of the present invention can also be directed to a method for manufacturing a hot-rolled steel sheet. In this exemplary method, a slab containing aforementioned components can be heated to at least a temperature satisfying the equation of SRT (° C.)=6670/{2.

Abstract: A steel sheet excellent in FB performance and also excellent in fabrication performance after FB working and a manufacturing method of the same are provided. The steel sheet is a steel sheet having a composition containing from 0.1 to 0.5% of C, not more than 0.5% of Si and from 0.2 to 1.5% of Mn in terms of % by mass, with P and S being adjusted at proper ranges and having a structure having a ferrite having an average grain size of more than 10 ?m and less than 20 ?m and a cementite present in the ferrite grain having an average particle size of from 0.3 to 1.5 ?m. In this way, the steel sheet becomes a steel sheet excellent in FB performance, mold life and performance (side bend elongation) after FB working.

Abstract: A cold-rolled steel sheet that is suitable for battery cases and has low anisotropy is composed of, by mass %, C: ?0.0030%, Si: ?0.02%, Mn: 0.15 to 0.19%, P: ?0.020%, S: ?0.015%, N: ?0.0040%, Al: 0.020 to 0.070%, Nb: 1.00?Nb/C (atomic equivalent ratio)?5.0, B: 1 ppm?B-(11/14)N?15 ppm (in the expression, B and N denote the contents of the respective elements), and the balance: being Fe and inevitable impurities, and has a planar anisotropy ?r of the r-value in the range of ?0.10??r?0.10. In a process for producing the steel sheet, the cold rolling is performed at a rolling ratio of 70 to 87%, and then annealing is performed on a continuous annealing line at an annealing temperature of from the recrystallization temperature to 830° C.

Abstract: A steel composition and method from making a dual phase steel therefrom. The dual phase steel may have carbon of about 0.05% by weight to about 0.12 wt %; niobium of about 0.005 wt % to about 0.03 wt %; titanium of about 0.005 wt % to about 0.02 wt %; nitrogen of about 0.001 wt % to about 0.01 wt %; silicon of about 0.01 wt % to about 0.5 wt %; manganese of about 0.5 wt % to about 2.0 wt %; and a total of molybdenum, chromium, vanadium and copper less than about 0.15 wt %. The steel may have a first phase consisting of ferrite and a second phase having one or more of carbide, pearlite, martensite, lower bainite, granular bainite, upper bainite, and degenerate upper bainite. A solute carbon content in the first phase may be about 0.01 wt % or less.

Abstract: In a high-tensile steel plate according to the invention, the carbon equivalent Pcm represented in Expression (1) is from 0.180% to 0.220%, the surface hardness is a Vicker's hardness of 285 or less, the ratio of a Martensite Austenite constituent in the surface layer is not more than 10%, the ratio of a mixed structure of ferrite and bainite inside beyond the surface layer is not less than 90%, the ratio of the bainite in the mixed structure is not less than 10%, the thickness of the lath of bainite is not more than 1 ?m, the length of the lath is not more than 20 ?m, and the segregation ratio as the ratio of the Mn concentration in the center segregation part relative to the Mn concentration at a part in a depth equal to ¼ of the thickness of the plate from the surface is not more than 1.3. Pcm=C+Si/30+(Mn+Cu+Cr)/20+Ni/60+Mo/15+V/10+5B . . . (1) where the element symbols in Expression (1) represent the % by mass of the respective elements.

Abstract: The invention provides wire rod excellent in drawability and steel wire made from the wire rod as starting material with high productivity at good yield and low cost. A hard steel wire rod of a specified composition is hot rolled, the hot-rolled steel is coiled in a specified temperature range, and the coiled steel is subjected to patenting at a predetermined cooling rate, thereby affording a high-carbon steel wire excellent in workability. It is high-strength steel wire excellent in drawability comprising a pearlite structure of an area ratio of 97% or greater and the balance of non-pearlite structures including bainite, degenerate-pearlite and pro-eutectoid ferrite and having a pearlite block size of not less than 20 ?m and not greater than 45 ?m. The invention also provides a high-carbon steel wire excellent in ductility, which is manufactured by subjecting the wire rod to intermediate patenting and cold drawing and has a tensile strength of 2800 MPa or greater.

Abstract: This disclosure relates to a high strength cold rolled steel sheet composed of ferrite grains having an average grain diameter of 10 ?m or less, in which the average number per unit area of Nb(C, N) precipitates having a diameter of 50 nm or more is 7.0×10?2/?m2 or less, and a zone having a width of 0.2 to 2.4 ?m and an average area density of NbC precipitates of 60% or less of that of the central portion of the ferrite grains is formed along grain boundaries of the ferrite grains, for example, the steel sheet consisting of 0.004 to 0.02% of C, 1.5% or less of Si, 3% or less of Mn, 0.15% or less of P, 0.02% or less of S, 0.1 to 1.5% of sol.Al, 0.001 to 0.007% of N, 0.03 to 0.2% of Nb, by mass, and the balance of Fe and inevitable impurities. The steel sheet is most preferably used for automobile panel parts since it has the TS of 340 MPa or more and the superior surface strain resistance and press formability.

Abstract: The invention provides a cold-rolled steel sheet excellent in paint bake hardenability and ordinary-temperature non-aging property comprising, in mass %, C: 0.0005-0.0040%, Si: 0.8% or less, Mn: 2.2% or less, S: 0.0005-0.009%, Cr: 0.4-1.3%, O: 0.003-0.020%, P: 0.045-0.12%, B: 0.0002-0.0010%, Al: 0.008% or less, N: 0.001-0.007%, and a balance of Fe and unavoidable impurities. Ultra-low-carbon steel retaining solute N and containing added Cr, P, B and O is used to produce hot-rolled and cold-rolled steel sheet and hot-dip galvanized cold-rolled steel sheet that exhibit both high paint bake hardenability and ordinary-temperature non-aging property.

Abstract: A high-strength steel pipe excellent in weldability on site and a method for producing the steel pipe by improving the reliability of the low temperature toughness of a steel are provided. For example, the steel pipe includes elements to enhance hardenability for furthering high-strengthening and also improving toughness at a weld heat affected zone subjected to double or more layer welding. In the method, the steel is made to consist of a structure composed of bainite and/or martensite by containing prescribed amounts of C, Si, Mn, P, S, Ni, Mo, Nb, Ti, Al and N, and, as occasion demands, one or more of B, V, Cu, Cr, Ca, REM, and Mg, and regulating C, Si, Mn, Cr, Ni, Cu, V and Mo. Such elements enhancing hardenability, by a specific relational expression. The diameter of prior austenite grains may be regulated in a prescribed range.

Abstract: The present invention provides high strength thick-gauge electric-resistance welded steel pipe excellent in hardenability, hot workability, and fatigue strength and a method of production of the same, that is, thick-gauge electric-resistance welded steel pipe containing, by mass %, C: 0.25 to 0.4%, Si: 0.01 to 0.50%, Mn: 0.8 to 1.5%, P: 0.05% or less, S: 0.05% or less, Al: 0.05% or less, Ti: 0.005 to 0.05%, B: 0.0005 to 0.01%, N: 0.001 to 0.05%, and a balance of Fe and unavoidable impurities, having a critical cooling rate Vc expressed by equation <1> of less than 30° C./s, and having a ratio of thickness t and outside diameter D, t/D, of over 0.15 to 0.30 in range: log Vc=2.94?0.75???<1> where, ?=2.7C+0.

Abstract: A steel sheet for forming having low-temperature heat treatment property, in which heat treatment is performed within a range of lower temperature than a conventional steel sheet in the event of hot press forming or post-heat treatment after cold forming, a method of manufacturing the same, and a method of manufacturing parts using the same. The steel sheet has a composition of, by weight, carbon (C): 0.15 to 0.35%, silicon (Si): 0.5% or less, manganese (Mn): 1.5 to 2.2%, phosphorus (P): 0.025% or less, sulfur (S): 0.01% or less, aluminum (Al): 0.01 to 0.05%, nitrogen (N): 50 to 200 ppm, titanium (Ti): 0.005 to 0.05%, tungsten (W): 0.005 to 0.1%, and boron (B): 1 to 50 ppm, wherein Ti/N: less than 3.4, where Ti/N is the atomic ratio of the corresponding elements, Ceq expressed by the following formula ranges from 0.48 to 0.58, and temperature Ar3 ranges from 670° C. to 725° C. Wherein Ceq=C+Si/24+Mn/6+Ni/40+Cr/5+V/14 where C, Si, Mn, Ni, Cr and V indicate the contents (wt %) of the respective elements.

Abstract: The present invention aims at providing a method for production of a steel product which surely retains scale during cooling, storage, and transportation and permits scale to scale off easily at the time of mechanical descaling and pickling that precede the secondary fabrication. The steel product is produced by heating and hot rolling a steel billet and spraying the hot-rolled steel product with steam and/or water mist having a particle diameter no larger than 100 ?m, for surface oxidation.

Abstract: A high strength wire rod in which an area fraction of pro-eutectoid ferrite is 3% or less and an area fraction of pearlite structure is 90% or more, being obtained by subjecting a hard steel wire rod having specified composition to a molten salt patenting treatment directly after hot-rolling or after performing re-austenitization subsequent to hot-rolling.

Abstract: Provided is a hot-rolled thin steel sheet having a thickness of less than 6 mm and having high strength showing a tensile strength of 440 MPa or more, excellent formability, and excellent strength and toughness after heat treatment and a method of manufacturing the same. A steel base material containing 0.10 to 0.20% of C, and Si, Mn, Al, P, S, and N adjusted to suitable amount ranges, and 0.01 to 0. 15% of Ti and 0.0005 to 0.0050% of B is hot rolled so as to have a finishing temperature of finish rolling of 820 to 880° C.; after the completion of the rolling, the hot-rolled thin steel sheet is cooled to a surface temperature range of 550 to 650° C. at a surface cooling rate of 15 to 50° C./s; and the hot-rolled thin steel sheet is coiled at the temperature range.

Abstract: Disclosed is a hardfacing alloy capable of withstanding service abrasion of the order of silicious earth particles and weldable on industrial products, such as tool joints and stabilizers used in oil and gas well drilling, and other industrial products. The hardfacing alloy has a low coefficient of friction resulting from excellent metal to metal resistance and significant reduction in industrial wear on industrial products, such as casing wear. Other embodiments of the invention include tool joints having the hardbanding alloy welded to the outer cylindrical surface to its box and pin members and to stabilizer ribs on the stabilizer used in earth boring, such as boring for oil and gas, other industrial products, and methods of applying the hardfacing alloy to their surfaces.

Abstract: The invention provides a high strength cold rolled steel sheet comprising ferrite phases and second phases, in which the mean grain size of the ferrite phases is 20 ?m or less, the volume fraction of the second phase is 0.1% or more to less than 10%, the absolute value |?r| of in-plane anisotropy of r value is less than 0.15, and the thickness is 0.4 mm or more. The high strength cold rolled steel sheet of the present invention has a tensile strength of 370 to 590 MPa, and has excellent stretchability, dent resistance, surface precision, secondary working embrittlement, anti-aging, and surface appearance, therefore it is suitable for outer panels of automobile.

Abstract: A hot press-formed member having stable strength and toughness is manufactured from a high strength steel sheet by hot press forming. In the cooling stage during hot press forming, the cooling rate is at least the critical cooling rate until the Ms point is reached and it is then in the range of 25-150° C./s in the temperature range from the Ms point to 200° C. The Vickers hardness of the hot pressed member is less than the value of (maximum quenching hardness—10) and at least the value of (maximum quenching hardness—100).

Abstract: The invention relates to a high strength, air-hardening, temper-resistant steel, which can easily be welded and galvanized and exhibits excellent shaping properties, particularly for the construction of lightweight vehicles. The inventive steel comprises the following elements (contents in mass %): C0.07 to ?0.15, Al?0.05, Si 0.15 to ?0.30, Mn 1.60 to ?2.10, P?0.020, S?0.010, N 0.0030 to ?0.0150, Cr 0.50 to ?1.0, Mo 0.30 to ?0.60, Ti 0.010 to ?0.050, V 0.12 to ?0.20, B 0.0015 to ?0.0040, remainder iron including incidental steel-accompanying elements.

Abstract: A steel sheet excellent in FB performance-and also excellent in fabrication performance after FB working and a manufacturing method of the same are provided. The steel sheet is a steel sheet having a composition containing from 0.1 to 0.5% of C, not more than 0.5% of Si and from 0.2 to 1.5% of Mn in terms of % by mass, with P and S being adjusted at proper ranges, and having a structure in which a ferrite has an average grain size of from 1 to 10 ?m, cementite has a spheroidization ratio of 80% or more, and of the cementite, an amount Sgb of ferrite intergranular cementite which is defined by the following expression (1): Sgb(%)={Son/(Son+Sin)}×100 (wherein Son represents a total occupied area of cementite present on the ferrite grain boundary of the cementite present per unit area; and Snin represents a total occupied area of cementite present in a ferrite grain of the cementite present per unit area) is 40% or more.

Abstract: A wire rod which is mainly composed of pearlite and has an area fraction of 5% or less of a non-pearlite structure composed of pro-eutectoid ferrite, degenerate-pearlite or bainite in a section, or has an area fraction of 10% or less of a non-pearlite structure in a portion from the surface to a depth of 100 ?m.

Abstract: The present invention provides an induction-hardened hollow driving shaft that comprises, as a raw material, a steel pipe that contains, by mass %, 0.30 to 0.47% C, 0.5% or less Si, 0.3 to 2.0% Mn, 0.018% or less P, 0.015% or less S, 0.15 to 1.0% Cr, 0.001 to 0.05% Al, 0.005 to 0.05% Ti, 0.004% or less Ca, 0.01% or less N, 0.0005 to 0.005% B and 0.0050% or less O (oxygen) and the balance Fe and impurities and of which Beff defined by an equation (a) or (b) below is 0.0001 or more, wherein a prior austenite grain size number (JIS G0551) after the hardening is 9 or more. Here, in the case of Neff=N?14×Ti/47.9?0, Beff=B?10.8×(N?14×Ti/47.9)/14 . . . (a), and, in other cases, Beff=B . . . (b). According to the present invention, a hollow driving shaft that is simultaneously provided with excellent cold workability, hardenability, toughness and torsional fatigue strength and can exert stable fatigue lifetime can be obtained and can be widely utilized.

Abstract: The invention concerns a method for making hardenable steel plates by firing comprising: preparing a steel whereof the composition comprises, expressed in weight percent: 0.03=C=0.06, 0.50=Mn=1.10, 0.08:=Si=0.20, 0.015=Al=0.070, N=0.007, Ni=0.040, Cu=0.040, P=0.035, S=0.015, Mo=0.010, Ti=0.005; provided that it comprises boron in an amount such that 0.64=B/N=1.60 the rest consisting of iron and impurities resulting from production; casting a slab of said steel, then hot rolling of said slab to obtain a plate, the final rolling temperature being higher than the point Ar3; winding said plate at a temperature ranging between 500 and 700° C.; then cold rolling of said plate at a reduction rate ranging between 50 and 80%; continuous annealing heat treatment for a time interval less than 15 minutes; and strain hardening with a reduction rate ranging between 1.25 and 2.5%. The invention also concerns the hardenable plates and the parts obtainable therefrom.

Abstract: Disclosed herein is a Nb—Ti composite IF steel in which fine precipitates, such as CuS precipitates, having a size of 0.2 ?m or less are distributed. The distribution of fine precipitates in the Nb—Ti composite IF steel enhances the yield strength and lowers the in-plane anisotropy index. The nanometer-sized precipitates allow the formation of minute crystal grains. As a result, dissolved carbon is present in a larger amount in the crystal grain boundaries than within the crystal grains, which is advantageous in terms of room-temperature non-aging properties and bake handenability.

Abstract: A high carbon hot-rolled steel sheet, as a hot-rolled spheroidizing annealed material, having both excellent stretch-flange formability and excellent homogeneity of hardness in the sheet thickness direction is provided by a manufacturing method having the steps of: hot-rolling a steel containing 0.2 to 0.7% C by mass at finishing temperatures of (Ar3 transformation point?20° C.) or above to prepare a hot-rolled sheet; cooling the hot-rolled sheet to temperatures of 650° C. or below at cooling rates from 60° C./s or larger to smaller than 120° C./s; coiling the hot-rolled sheet after cooling at coiling temperatures of 600° C. or below; and annealing the coiled hot-rolled sheet at annealing temperatures from 640° C. or larger to Ac1 transformation point or lower.