Abstract: Disclosed is, as a high-strength steel plate of API X80 grade or higher with a thickness of 38 mm or more, a thick steel plate for structural pipes or tubes that exhibits high strength in the rolling direction and excellent Charpy properties at its mid-thickness part without addition of large amounts of alloying elements. The thick steel plate for structural pipes or tubes disclosed herein has: a specific chemical composition; a microstructure at its mid-thickness part that is a dual-phase microstructure of ferrite and bainite with an area fraction of the ferrite being less than 50%, and that contains ferrite grains with a grain size of 15 ?m or less in an area fraction of 80% or more with respect to the whole area of the ferrite; a tensile strength of 620 MPa or more; and a Charpy absorption energy vE?20+ C. at ?20° C. at the mid-thickness part of 100 J or more.

Abstract: An object is to provide a steel plate having excellent deformability in the central portion in the thickness direction and a method for manufacturing the steel plate. A steel plate having a chemical composition containing, by mass %, C: 0.01% to 0.15%, Si: 0.01% to 1.00%, Mn: 0.10% to 2.00%, P: 0.010% or less, S: 0.0050% or less, Al: 0.002% to 0.100%, Ni: 5.0% to 10.0%, N: 0.0010% to 0.0080%, and with a balance being Fe and incidental impurities and a percentage reduction of area of 30% or more in a tensile test in the thickness direction performed on the central portion in the thickness direction.

Abstract: Disclosed is, as a high-strength steel plate of API X80 grade or higher with a thickness of 38 mm or more, a steel plate for structural pipes or tubes that exhibits excellent resistance to PWHT and excellent toughness at the heat-affected zone, particularly at the butting faces joined by welding, without addition of large amounts of alloying elements. The steel plate for structural pipes or tubes disclosed herein has a specific chemical composition, in which the steel plate has mechanical properties including: (a) a 0.5% yield strength of 555 MPa or more; (b) a tensile strength of 625 MPa or more; and (c) a Charpy absorption energy vE?10° C. at ?10° C. at its mid-thickness part of 250 J or more, and maintains the mechanical properties (a) to (c) even after subjection to heat treatment at 650° C. for 2 hours.

Abstract: A high-strength steel having a specified chemical composition, wherein parameter Peff is 0.050% or more, the relationship (TS0?TS)/TS0?0.050 is satisfied, wherein TS is defined as tensile strength determined at a temperature of 350° C. after aging has been performed under the condition of a Larson-Miller Parameter (LMP) of 15700, and wherein TS0 is defined as tensile strength determined at a temperature of 350° C. before the aging is performed, and having a toughness represented by a vE?20 of 100 J or more in a weld heat-affected zone, which is formed when welding is performed.

Abstract: Disclosed is, as a high-strength steel plate of API X80 grade or higher with a thickness of 38 mm or more, a thick steel plate for structural pipes or tubes that exhibits high strength in the rolling direction, excellent Charpy properties at its mid-thickness part, and high material homogeneity without addition of large amounts of alloying elements. The thick steel plate for structural pipes or tubes disclosed herein has: a specific chemical composition; a microstructure mainly composed of bainite; a tensile strength of 620 MPa or more; a Charpy absorption energy vE?20° C. at ?20° C. at the mid-thickness part of 100 J or more; a variation of Vickers hardness in a plate thickness direction ?HV10,t of 50 or less; and a variation of Vickers hardness in a plate widthwise direction ?HV10,c of 50 or less.

Abstract: High-strength steel having a specified chemical composition, wherein X (%) calculated by using equation (1): X=0.35Cr+0.9Mo+12.5Nb+8V??(1) is 0.75% or more, wherein the symbols of chemical elements in equation (1) respectively denote the contents (mass %) of the corresponding chemical elements and wherein the symbol of a chemical element which is not included is assigned a value of 0, a microstructure having a bainite phase fraction of 50% or more, a dislocation density of 1.0×1015/m2 or more after aging has been performed under the condition of a Larson-Miller parameter (LMP) of 15000, and a yield strength of 550 MPa or more before and after the aging is performed, as well as methods of manufacturing such high-strength steel, is disclosed. The high-strength steel can be used as a raw material for manufacturing large diameter steel pipe having the strength properties required for its use in steam transportation.

Abstract: A high strength/highstrength, high toughness steel sheet having tensile strength, Charpy impact absorption energy, and ductile fracture rate are equal to or greater than specified values comprises, in mass %, 0.03-0.08% of C, 0.01-0.50% of Si, 1.5-2.5% of Mn, 0.001-0.010% of P, 0.0030% or less of S, 0.01-0.08% of Al, 0.010-0.080% of Nb, 0.005-0.025% of Ti, 0.001-0.006% of N, at least one substance selected from among 0.01-1.00% of Cu, 0.01-1.00% of Ni, 0.01-1.00% of Cr, 0.01-1.00% of Mo, 0.01-0.10% of V, and 0.0005-0.0030% of B, and a remainder of Fe and unavoidable impurities. At a position at ½ the sheet thickness, the area ratio of island-like martensite is less than 3%, the area ratio of bainite is 90% or more, and the average particle size of cementite within the bainite is 0.5 ?m or less.

Abstract: A high strength/highstrength, high toughness steel sheet having tensile strength, Charpy impact absorption energy, and ductile fracture rate are equal to or greater than specified value comprises, in mass %, 0.03-0.08% of C, 0.01-0.50% of Si, 1.5-2.5% of Mn, 0.001-0.010% of P, 0.0030% or less of S, 0.01-0.08% of Al, 0.010-0.080% of Nb, 0.005-0.025% of Ti, 0.001-0.006% of N, at least one substance selected from among 0.01-1.00% of Cu, 0.01-1.00% of Ni, 0.01-1.00% of Cr, 0.01-1.00% of Mo, 0.01-0.10% of V, and 0.0005-0.0030% of B, and a remainder of Fe and unavoidable impurities. At a position at ½ the sheet thickness, the area ratio of island-like martensite is less than 3%, the area ratio of bainite is 90% or more, and the average particle size of cementite within the bainite is 0.5 ?m or less.

Abstract: Disclosed is, as a high-strength steel plate of API X80 grade or higher with a thickness of 38 mm or more, a thick steel plate for structural pipes or tubes that exhibits high strength in the rolling direction and excellent Charpy properties at its mid-thickness part without addition of large amounts of alloying elements. The thick steel plate for structural pipes or tubes disclosed herein has: a specific chemical composition; a microstructure at its mid-thickness part that is a dual-phase microstructure of ferrite and bainite with an area fraction of the ferrite being less than 50%, and that contains ferrite grains with a grain size of 15 ?m or less in an area fraction of 80% or more with respect to the whole area of the ferrite; a tensile strength of 620 MPa or more; and a Charpy absorption energy vE?20+ C. at ?20° C. at the mid-thickness part of 100 J or more.

Abstract: Disclosed is, as a high-strength steel plate of API X80 grade or higher with a thickness of 38 mm or more, a steel plate for structural pipes or tubes that exhibits excellent resistance to PWHT and excellent toughness at the heat-affected zone, particularly at the butting faces joined by welding, without addition of large amounts of alloying elements. The steel plate for structural pipes or tubes disclosed herein has a specific chemical composition, in which the steel plate has mechanical properties including: (a) a 0.5% yield strength of 555 MPa or more; (b) a tensile strength of 625 MPa or more; and (c) a Charpy absorption energy vE?10° C. at ?10° C. at its mid-thickness part of 250 J or more, and maintains the mechanical properties (a) to (c) even after subjection to heat treatment at 650° C. for 2 hours.

Abstract: Disclosed is, as a high-strength steel plate of API X100 grade or higher, a steel plate for structural pipes or tubes that exhibits high strength in a rolling direction and that has only a small difference between strength in a rolling direction and strength in a direction perpendicular to the rolling direction (exhibiting high material homogeneity) without addition of large amounts of alloying elements. The steel plate for structural pipes or tubes disclosed herein has: a specific chemical composition; a microstructure mainly composed of bainite and containing martensite austenite constituent in an area fraction of less than 3.0%; a tensile strength in the rolling direction of 760 MPa or more; and TSC?TSL being 30 MPa or less in terms of absolute value, where TSC denotes a tensile strength in a direction perpendicular to the rolling direction.

Abstract: Disclosed is, as a high-strength steel plate of API X80 grade or higher with a thickness of 38 mm or more, a thick steel plate for structural pipes or tubes that exhibits high strength in the rolling direction and excellent Charpy properties at its mid-thickness part without addition of large amounts of alloying elements. The thick steel plate for structural pipes or tubes disclosed herein has: a specific chemical composition; a microstructure at its mid-thickness part that is a dual-phase microstructure of ferrite and bainite with an area fraction of the ferrite being less than 50%, and that contains ferrite grains with a grain size of 15 ?m or less in an area fraction of 80% or more with respect to the whole area of the ferrite; a tensile strength of 620 MPa or more; and a Charpy absorption energy vE?20+ C. at ?20° C. at the mid-thickness part of 100 J or more.

Abstract: High-strength steel having a specified chemical composition wherein the ratio of Ti to N, Ti/N, is 2.0 to 4.0, and X (%), as calculated by equation (1): X=0.35Cr+0.9Mo+12.5Nb+8V (1) is 0.90% or more, wherein the symbols of chemical elements in equation (1) respectively denote the contents (mass %) of the corresponding chemical elements and wherein the symbol of a chemical element which is not included is assigned a value of 0, a microstructure having a bainite phase fraction of 70% or more, and a tensile strength of 760 MPa or more at a temperature of 350°C., methods for manufacturing such high-strength steel, and methods for manufacturing steel pipe from such high-strength steel, is disclosed.

Abstract: A high-strength steel having a specified chemical composition, wherein parameter Peff is 0.050% or more, the relationship (TS0?TS)/TS0?0.050 is satisfied, wherein TS is defined as tensile strength determined at a temperature of 350° C. after aging has been performed under the condition of a Larson-Miller Parameter (LMP) of 15700, and wherein TS0 is defined as tensile strength determined at a temperature of 350° C. before the aging is performed, and having a toughness represented by a vE?20 of 100 J or more in a weld heat-affected zone, which is formed when welding is performed.

Abstract: Disclosed is, as a high-strength steel plate of API X80 grade or higher with a thickness of 38 mm or more, a steel plate for structural pipes or tubes that exhibits excellent resistance to PWHT and excellent toughness at the heat-affected zone, particularly at the butting faces joined by welding, without addition of large amounts of alloying elements. The steel plate for structural pipes or tubes disclosed herein has a specific chemical composition, in which the steel plate has mechanical properties including: (a) a 0.5% yield strength of 555 MPa or more; (b) a tensile strength of 625 MPa or more; and (c) a Charpy absorption energy vE?10° C. at ?10° C. at its mid-thickness part of 250 J or more, and maintains the mechanical properties (a) to (c) even after subjection to heat treatment at 650° C. for 2 hours.

Abstract: Disclosed is, as a high-strength steel plate of API X100 grade or higher, a steel plate for structural pipes or tubes that exhibits high strength in a rolling direction and that has only a small difference between strength in a rolling direction and strength in a direction perpendicular to the rolling direction (exhibiting high material homogeneity) without addition of large amounts of alloying elements. The steel plate for structural pipes or tubes disclosed herein has: a specific chemical composition; a microstructure mainly composed of bainite and containing martensite austenite constituent in an area fraction of less than 3.0%; a tensile strength in the rolling direction of 760 MPa or more; and TSC?TSL being 30 MPa or less in terms of absolute value, where TSC denotes a tensile strength in a direction perpendicular to the rolling direction.

Abstract: Disclosed is, as a high-strength steel plate of API X80 grade or higher with a thickness of 38 mm or more, a thick steel plate for structural pipes or tubes that exhibits high strength in the rolling direction, excellent Charpy properties at its mid-thickness part, and high material homogeneity without addition of large amounts of alloying elements. The thick steel plate for structural pipes or tubes disclosed herein has: a specific chemical composition; a microstructure mainly composed of bainite; a tensile strength of 620 MPa or more; a Charpy absorption energy vE?20° C. at ?20° C. at the mid-thickness part of 100 J or more; a variation of Vickers hardness in a plate thickness direction ?HV10,t of 50 or less; and a variation of Vickers hardness in a plate widthwise direction ?HV10,c of 50 or less.

Abstract: High-strength steel having a specified chemical composition, wherein X (%) calculated by using equation (1): X=0.35Cr+0.9Mo+12.5Nb+8V??(1) is 0.75% or more, wherein the symbols of chemical elements in equation (1) respectively denote the contents (mass %) of the corresponding chemical elements and wherein the symbol of a chemical element which is not included is assigned a value of 0, a microstructure having a bainite phase fraction of 50% or more, a dislocation density of 1.0×1015/m2 or more after aging has been performed under the condition of a Larson-Miller parameter (LMP) of 15000, and a yield strength of 550 MPa or more before and after the aging is performed, as well as methods of manufacturing such high-strength steel, is disclosed. The high-strength steel can be used as a raw material for manufacturing large diameter steel pipe having the strength properties required for its use in steam transportation.

Abstract: A self-stop circuit has a nonvolatile storage element (20), and a write terminal (50) and an erase circuit (30) for controlling the amount of electric charges charged in or discharged from the nonvolatile storage element (20). A determination circuit (40) determines that the amount of electric charges accumulated in the nonvolatile storage element (20) falls below a threshold, so as to detect an elapsed time. Thereby, the end of the lifespan of a product is detected and the operation of the product is stopped or modified after the end of the lifespan. When the operation is desired to be restored, electric charges are injected into the nonvolatile storage element (20) again, or a cancel signal is supplied through an external terminal (53) to the determination circuit (40).

Abstract: A power supply potential and a ground potential are supplied to a test-use power supply pad and a test-use ground pad, respectively. The power supply potential supplied to the test-use power supply pad is transferred to power supply lines and then to each circuit block via a test-use power supply line and a potential transfer circuit including a diode device. A voltage drop is caused by each of the diode devices. To cope with the voltage drop, however, respective sizes of the diode devices and resistance components of the potential transfer circuits are configured so that a uniform voltage drop is generated at each of the power supply lines.