Abstract: The present invention provides a duplex stainless steel having excellent resistance to alkalis and particularly corrosion resistance against high-temperature concentrated alkali solutions and excellent weldability. The duplex stainless steel has a chemical composition comprising, in mass %, C: at most 0.03%, Si: at most 0.5%, Mn: at most 2.0%, P: at most 0.04%, S: at most 0.003%, Cr: at least 25.0% to less than 28.0%, Ni: at least 6.0% to at most 10.0%, Mo: at least 0.2% to at most 3.5%, N: less than 0.5%, W: at most 3.0%, and a remainder of Fe and impurities.

Abstract: The galling resistance of a threaded joint for steel pipes which satisfies the standards for an API round threaded joint and which has a pin with triangular male threads and a box with triangular female threads which threadingly engage with the male threads and an unthreaded sleeve positioned at the end of the box is improved. The unthreaded sleeve is shortened or removed so that the length of the unthreaded sleeve in the axial direction of the box becomes at most ½ (including 0) of the value specified by the above standards. The shape of the box specified by the above standards may be modified by providing a swoosh portion at the end of the box and/or by making the bevel angle at the end of the female threads ±15 degrees of the flank angle of the female threads.

Abstract: An assembly for producing a threaded connection, including first and second tubular components with an axis of revolution, each including at one end a male threaded zone produced on the external circumferential surface, the ends each finishing in a terminal surface forming a direct drive dog clutch device to fix the first and second tubular components in rotation, and including a third tubular component which also has an axis of revolution and includes at each end on its internal circumferential surface two female threaded zones, one of the two male threaded zones being capable of cooperating with one of the two female threaded zones while the other male threaded zone can co-operate with the other female threaded zone. The male end of the first tubular component and the corresponding female end of the third tubular component include a mechanism for free rotation.

Abstract: An austenitic stainless steel sheet for springs having both a high strength and excellent formability has a chemical composition comprising C: 0.01-0.15%, Si: at most 3.0%, Mn: at most 3.0%, Cr: 10.0-30.0%, Ni: 4.0-20.0%, N: at most 0.40%, and a remainder of Fe and impurities, and it has a metallurgical structure such that the austenite content ?s (%) in the surface region of the steel sheet and the austenite content ?c (%) in the center region of the sheet thickness satisfy (?s+?c)/2?55 and ?s/?c?0.10, with the remaining structure being primarily strain-induced martensite.

Abstract: It is an object of the present invention to provide an eddy current testing method capable of securely detecting a high hardness part locally occurring in a metal material having magnetism, and capable of securely checking whether the high hardness part has been removed after execution of a repairing treatment for removing the high hardness part. In the eddy current testing method according to the present invention, a frequency of the AC current for energizing the differential coil 1 is set so that a phase difference between a magnetism variation signal of the metal material P and a liftoff signal detected by the differential coil is equal to or larger than 135°, and a local high hardness part occurring in the metal material is detected based on an amplitude and a phase of a detection signal outputted from the differential coil.

Abstract: A method of producing steel for a steel pipe excellent in sour-resistance performance comprises controlling the amount of Ca addition charged into a molten steel in a ladle according to a N content in the molten steel prior to Ca addition. Non-metallic inclusions in the steel are mainly composed of Ca, Al, 0 and S, and a CaO content in the inclusions is in the range of 30 to 80%, the ratio of the N content in the steel to the CaO content in the inclusions satisfying equation (1), and a CaS content in the inclusions satisfies equation (2), 0.28?[N]/(% CaO)?2.0??(1) (% CaS)?25%??(2) where [N] represents the mass content (ppm) of N in the steel, (% CaO) represents the mass content (%) of CaO in the inclusions, and (% CaS) represents the mass content (%) of CaS in the inclusions.

Abstract: An anti-seizure agent for hot steel working that exhibits excellent wettability and surface film-adherability comprises: an inorganic component (first component); sodium hydroxide (second component); water-soluble resins and/or water-soluble surfactants (third component); and water. With the mass of the sum of the first component, the second component, and the third component as 100 mass %, the anti-seizure agent contains: 96.5 mass % or more and 99.98 mass % or less of the first component; 0.01 mass % or more and 2.0 mass % or less of the second component; and 0.01 mass % or more and 1.5 mass % or less of the third component, and the inorganic component is one or more selected from a group consisting of Al2O3, SiO2, CaO, B2O3, K2O, and Na2O. A coating layer formed after application solidly adheres to the steel and does not come off in the environment of both cold and hot working.

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: The present invention provides a manufacturing apparatus of a hot-rolled steel sheet capable of cooling control of a steel sheet even when disposing a cooling device capable of cooling from inside a finishing mill. The manufacturing apparatus of a hot-rolled steel sheet comprises: an immediate rapid-cooling device capable of spraying cooling water, at least a part thereof being disposed inside a final stand in the row of hot finishing mills; a device for measuring a temperature on an entry side of a final stand; a device for measuring a steel sheet passing speed; a device for predicting a rapid-cooling stopping temperature which calculates a predicted rapid-cooling stopping temperature; and an immediate rapid-cooling control device which corrects the water supply volume or water supply pressure of the immediate rapid-cooling device such that the predicted rapid-cooling stopping temperature matches a targeted rapid-cooling stopping temperature.

Abstract: The present invention provide a manufacturing method of a hot-rolled steel sheet capable of providing a target temperature for temperature of a rolled material in a final stand in a row of hot finishing mills, even when disposing a cooling device capable of cooling from inside the row of hot finishing mills. The method comprises: rapidly cooling the rolled material by spraying cooling water at inside of the final stand on a lower process side of the final stand in the row of hot finishing mills; obtaining an entry-side surface temperature of the rolled material on an entry side of the final stand; and calculating a target surface temperature on the entry side of the final stand, from a target surface temperature on the exit side of the final stand, based on generated heat and temperature reductions by contact of work rolls with the rolled material and by air cooling.

Abstract: A method of making an UOE steel pipe having excellent deformability and low-temperature toughness includes providing a steel composition with a controlled composition consisting essentially of C: 0.03-0.07%, Si: 0.05-0.50%, Mn: 1.6-2.2%, P: at most 0.020%, S: at most 0.003%, Cu: 0.20-0.60%, Cr: at most 0.10%, Ni: 0.20-0.80%, Nb: 0.005-0.030%, Ti: 0.005-0.030%, N: at most 0.0070%, Al: 0.005-0.060%, and a remainder of Fe and impurities, a hardenability index Pcm of at most 0.22%, Cu+Cr+Ni is 0.4-1.5%, and Nb+Mo+V is at most 0.05%. The pipe has a yield strength in the longitudinal direction of at least 480 MPa, a yield-tensile ratio of at most 85% and a Charpy absorbed energy of the heat affected zone at ?40° C. of at least 40 J.

Abstract: A plug includes a front edge portion having a convex curvature; a cylindrical portion having a truly or nearly cylindrical shape; a trunk portion having an outer diameter gradually increasing toward a rear edge thereof; a mandrel joint provided in a rear edge portion of the plug; a lubricant ejection hole running through the trunk portion from the mandrel joint that opens on the surface of the cylindrical portion; and a coating comprising oxides and Fe that is formed on the base metal surface of each of the front edge portion as well as the trunk portion by arc spraying using an iron wire. In this way, the plug can prevent inner surface flaws from occurring in a hollow blank that is deformed by piercing-rolling, and can extend its life without requiring a long time for making it.

Abstract: A SiC single crystal wafer on which a good quality epitaxial film by suppressing defects derived from the wafer can be grown has an affected surface layer with a thickness of at most 50 nm and a SiC single crystal portion with an oxygen content of at most 1.0×1017 atoms/cm3. This SiC single crystal wafer is manufactured from a high purity SiC bulk single crystal obtained by the solution growth method using raw materials with an oxygen content of at most 100 ppm and a non-oxidizing atmosphere having an oxygen concentration of at most 100 ppm.

Abstract: A method for producing a carbonitrided member comprising the steps of carburizing a steel part having a composition of, by mass percent, C: 0.10 to 0.35%, Si: 0.15 to 1.0%, Mn: 0.30 to 1.0%, Cr: 0.40 to 2.0%, S: 0.05% or less with the balance being Fe and impurities in a carburizing atmosphere of 900 to 950° C. The carburized steel part is carbonitrided in a carbonitriding atmosphere with the temperature of 800 to 900° C. and the nitrogen potential of 0.2 to 0.6%. The carbonitrided steel part is qhenched and then shot peened. The shot peening treatment may be further performed while heating to a temperature not higher than 350° C. or immediately after heating to a temperature not higher than 350° C. After quenching, the shot peening treatment may be further performed after tempering in the temperature range exceeding 250° C. and not higher than 350° C.

Abstract: A method of producing an ultrathin-wall metal tube by a cold drawing method includes a diameter-expanding drawing method, in which an entry solid die, the diameter of which increases, remains constant or decreases from the engaging entry side toward the finishing exit side, and a delivery solid die, the diameter of which decreases at least in the vicinity of the engaging entry, are arranged in series and in an abutting relation on the same pass line. A tapered plug, the diameter of which increases from the engaging entry side toward the finishing exit side, floats along the pass line, whereby in the entry solid die region, the wall thickness is reduced while the mid-wall diameter of a hollow shell is being expanded between the solid die and the plug, and in the delivery solid die region, the tapered plug floats by performing reduction working of the outside diameter.

Abstract: The high-strength Ni-based alloy tube for nuclear power use consists, by mass percent, of C: 0.04% or less, Si: 0.10 to 0.50%, Mn: 0.05 to 0.50%, Ni: 55 to 70%, Cr: more than 26% and not more than 35%, Al: 0.005 to 0.5%, N: 0.02 to 0.10%, and one or more kinds of Ti: 0.01 to 0.5% and Nb: 0.02 to 1.0%, the balance being Fe and impurities. For this alloy tube, the grain size is as fine as grain size No. 6 or higher in JIS G 0551. It is preferable that the high-strength Ni-based alloy tube be manufactured by the process of preparing a Ni-based alloy stock through a remelting process, hot forging, heating to 1000 to 1160° C., hot extruding at a working ratio such that an extrusion ratio is 4 or higher, and performing solution annealing and thermal treatment.

Abstract: A starting material to be extruded made of a high alloy comprising, in mass %, Cr: 20 to 30% and Ni: more than 22% and 60% or less is heated to a temperature predetermined according to the contents of Mo and W and is subjected to a hot-extrusion process, the heating temperature T (° C.) satisfying a relationship of Formula (1), (2), or (3), which is expressed in terms of the average cross-sectional area A (mm2) of the starting material to be extruded, the extrusion ratio EL (?), and the extrusion speed V (mm/s). As a result, a high-alloy seamless tube can be produced without generating cracking and/or seam flaws. When 0%?Mo+0.5W<4%: T?1343?0.001322×A?1.059×EL?0.129×V??(1) When 4%?Mo+0.5W<7%: T?1316?0.001322×A?1.059×EL?0.129×V??(2) When 7%?Mo+0.5W: T?1289?0.001322×A?1.059×EL?0.

Abstract: A steel tube for an airbag which has a low alloy cost and a strength of at least 1000 MPa and vTrs100 of ?80° C. or below and a process for its manufacture which can minimize the number of times that softening annealing treatment is performed in a cold drawing step are provided. Stable properties are obtained even when quench hardening is carried out by high frequency induction heating on a large scale. The steel tube has a steel composition which comprisise, in mass percent, C: 0.05-0.20%, Si: 0.10-0.50%, Mn: 0.10-1.00%, P: at most 0.025%, S: at most 0.005%, Al: 0.005-0.10%, Ca: 0.0005-0.0050%, Nb: 0.005-0.050%, Ti: 0.005-0.050%, Cu: 0.01-0.50%, Ni: 0.01-0.50%, Cr: 0.01-0.50%, B: 0.0005-0.0050%, N: 0.002-0.010%, and a remainder of Fe and unavoidable impurities.

Abstract: A method for measuring flatness of a sheet material in which a light and dark pattern composed by a light portion and a dark portion is projected onto a surface of the sheet material running in a longitudinal direction, a pattern image is acquired by photographing the light and dark pattern by an image pickup device having an image pickup visual field larger than a width of the sheet material, and the flatness of the sheet material is measured by analyzing the acquired pattern image. A staggered pattern is used for the projecting step and for light to be specularly reflected for receipt by the image pickup device. Calculating the flatness also includes steps of setting a shape measurement line, averaging picture element concentrations, calculating a distribution of the concentrations, and calculating the flatness based on surface shape using the distribution.

Abstract: A Ni—Cr alloy tube demonstrating an excellent corrosion resistance in a high temperature water environment can be provided, wherein the difference between uniform lattice strains of the surface layer thereof satisfies the following formulas (1) and (2). S?0.002??(1) S=D500?D?200??(2) wherein the meanings of the individual symbols in the above described formulas are as follows: S: The difference between uniform lattice strains (?) of the surface layer D500: The {111} interplanar spacing (?) at a depth of 500 nm from the material surface D?200: The average value of the {111} interplanar spacings (?) at the depth of 200 nm or less from the material surface.