Abstract: A high-strength steel sheet with excellent delayed fracture resistance, having a tensile strength of 1700 MPa or larger, including a predetermined component composition, having a martensite structure whose ratio accounts for 95 area % or more of the entire metallographic structure, and having a transition metal carbide whose ratio accounts for 0.8 volume % or more of the entire metallographic structure.

Abstract: A hydrogen permeability testing device can measure hydrogen amount(s) entering a metal material by electrochemical hydrogen permeation. The device may include: a metal specimen having a hydrogen entry face through which hydrogen enters, a hydrogen detection face on which the entered hydrogen is detected, and a metal plating formed on the hydrogen detection face to detect the entered hydrogen; a reference and counter electrode for making an electrochemical reaction progress; an electrolytic vessel provided on a hydrogen detection face side, housing the reference and counter electrode, and containing an aqueous sodium silicate solution having a freezing point of ?0° C. and capable of suppressing residual current to ?10 nA/cm2 when an electric potential of the hydrogen detection face is ?1 to 1 V relative to the reference electrode; and a measurement unit which measures the amount of hydrogen based on a current value resulting from the electrochemical reaction.

Abstract: Disclosed herein is a duplex stainless steel material including a ferrite phase and an austenite phase, wherein the steel material contains, as metal component composition, at least one X-group element selected from 0.01 to 0.50 mass % of V, 0.0001 to 0.0500 mass % of Ti, 0.0005 to 0.0500 mass % of Nb, and 0.01 to 0.50 mass % of Ta. The steel material has composite inclusions or has composite inclusions and inclusions, in which each of the inclusions includes at least one of an oxide, a sulfide, and an oxysulfide; each of the composite inclusions includes one of the inclusions as a nucleus and includes an outer shell existing around the nucleus and having a carbide or a nitride containing Cr and the at least one X-group element, and the proportion of the number of the composite inclusions with respect to the total number of the inclusions is 30% or more.

Abstract: Disclosed is a high strength steel sheet having excellent hydrogen embrittlement resistance. The steel sheet has a tensile strength of 1180 MPa or more, and satisfies the following conditions: with respect to an entire metallographic structure thereof, bainite, bainitic ferrite and tempered martensite account for 85 area % or more in total; retained austenite accounts for 1 area % or more; and fresh martensite accounts for 5 area % or less (including 0 area %).

Abstract: This duplex stainless steel material is composed of a ferrite phase and an austenite phase, and has a component composition that contains 0.100% by mass or less of C, 0.10-2.00% by mass of Si, 0.10-2.00% by mass of Mn, 0.050% by mass or less of P, 0.0100% by mass or less of S, 0.001-0.050% by mass of Al, 1.0-10.0% by mass of Ni, 22.0-28.0% by mass of Cr, 2.0-6.0% by mass of Mo and 0.20-0.50% by mass of N, while containing 0.01-0.50% by mass of Ta and/or 0.1-1.0% by mass of Ge, with the balance made up of Fe and unavoidable impurities.

Abstract: Disclosed is a high-strength cold-rolled steel sheet having improved stretch-flange formability and excellent hydrogen embrittlement resistance. In addition to Fe, C, Si, Mn, P, S, N, and Al, the steel sheet contains V or at least one element of Nb, Ti and Zr. The contents of the at least one element of Nb, Ti and Zr, if present, satisfy the expression of [% C]?[% Nb]/92.9×12?[% Ti]/47.9×12?[% Zr]/91.2×12>0.03. The steel sheet has an area ratio of tempered martensite of 50% or more with ferrite as the remainder. The number of precipitates having a circle-equivalent diameter of 1 to 10 nm is 20 particles or more per 1 ?m2 of the tempered martensite. The number of precipitates containing V or the at least one element of Nb, Ti and Zr and having a circle-equivalent diameter of 20 nm or more is 10 particles or less per 1 ?m2 of the tempered martensite.

Abstract: The present invention is the thin steel sheet containing C, Si, Mn, P, S, Al, Mo, Ti, B, and N wherein a value Z calculated by the equation described below is 2.0-6.0, an area ratio against all the structure is 1% or above for retained austenite and 80% or above for total of bainitic ferrite and martensite, a mean axis ratio of the retained austenite crystal grain is 5 or above, and tensile strength is 980 MPa or above where Value Z=9×[C]+[Mn]+3×[Mo]+490×[B]+7×[Mo]/{100×([B]+0.001),and the thin steel sheet has 980 MPa or above tensile strength and enhanced hydrogen embrittlement resistance properties.

Abstract: An aluminum alloy material having an excellent sea water corrosion resistance comprises an aluminum alloy substrate whose ten-points average surface roughness Rz, which is the average of five greatest peak-to-valley separations on the surface, is controlled at 0.3 ?m or over, an organic phosphonic primer film formed on a surface of the aluminum alloy substrate, and a fluorine resin paint film formed on the primer film and having a dry average thickness of 1 to 100 ?m. A plate heat exchanger having an excellent sea water corrosion resistance is also provided wherein the aluminum alloy material is used as a heat transfer unit using sea water as cooling water.

Abstract: Disclosed are an aluminum alloy material and a plate heat exchanger using the aluminum alloy material, both of which have superior corrosion resistance. Specifically, the aluminum alloy material includes an aluminum alloy base material having an anodic oxide layer with an average thickness of 1 to 20 ?m as its surface layer, an organic phosphonic acid primer coating arranged on the surface of the aluminum alloy base material, and a fluorocarbon resin coating arranged on the surface of the organic phosphonic acid primer coating and having an average thickness of 1 to 100 ?m after drying.

Abstract: Disclosed is a high strength steel sheet having excellent hydrogen embrittlement resistance. The steel sheet has a tensile strength of 1180 MPa or more, and satisfies the following conditions: with respect to an entire metallographic structure thereof, bainite, bainitic ferrite and tempered martensite account for 85 area % or more in total; retained austenite accounts for 1 area % or more; and fresh martensite accounts for 5 area % or less (including 0 area %).

Abstract: Disclosed is a high-strength cold-rolled steel sheet which has improved stretch-flange formability while keeping excellent hydrogen embrittlement resistance. The cold-rolled steel sheet comprises 0.03 to 0.30% by mass of C, 3.0% by mass or less (including 0% by mass) of Si, more than 0.1% by mass and not more than 2.8% by mass of Mn, 0.1% by mass or less of P, 0.005% by mass or less of S, 0.01% by mass or less of N, and 0.01 to 0.50% by mass of Al. The cold-rolled steel sheet additionally comprises V in an amount of 0.001 to 1.00% by mass or one or more elements selected from Nb, Ti and Zr in the total amount of 0.01% by mass or more, with the remainder being made up by iron and unavoidable impurities, wherein the contents of one or more elements selected from Nb, Ti and Zr fulfils the requirement represented by the following formula: [% C]?[% Nb]/92.9×12?[% Ti]/47.9×12?[% Zr]/91.2×12>0.03.

Abstract: The invention relates to an ultrahigh-strength thin steel sheet excellent in the hydrogen embrittlement resistance, the steel sheet including, by weight %, 0.10 to 0.60% of C, 1.0 to 3.0% of Si, 1.0 to 3.5% of Mn, 0.15% or less of P, 0.02% or less of S, 1.5% or less of Al, 0.003 to 2.0% of Cr, and a balance including iron and inevitable impurities; in which grains of residual austenite have an average axis ratio (major axis/minor axis) of 5 or more, the grains of the residual austenite have an average minor axis length of 1 ?m or less, and the grains of the residual austenite have a nearest-neighbor distance between the grains of 1 ?m or less.

Abstract: The present invention is the thin steel sheet containing C, Si, Mn, P, S, Al, Mo, Ti, B, and N wherein a value Z calculated by the equation described below is 2.0-6.0, an area ratio against all the structure is 1% or above for retained austenite and 80% or above for total of bainitic ferrite and martensite, a mean axis ratio of the retained austenite crystal grain is 5 or above, and tensile strength is 980 MPa or above. Value Z=9×[C]+[Mn]+3×[Mo]+490×[B]+7×[Mo]/{100×([B]+0.001)} Thus a high strength thin steel sheet with 980 MPa or above tensile strength and enhanced hydrogen embrittlement resistance properties can be provided. Also, in accordance with the present invention, the hot-rolled steel sheet for cold-rolling capable of manufacturing the high strength thin steel sheet with good productivity and having improved cold-rollability can be provided.

Abstract: Disclosed are an aluminum alloy material and a plate heat exchanger using the aluminum alloy material, both of which have superior corrosion resistance. Specifically, the aluminum alloy material includes an aluminum alloy base material having an anodic oxide layer with an average thickness of 1 to 20 ?m as its surface layer, an organic phosphonic acid primer coating arranged on the surface of the aluminum alloy base material, and a fluorocarbon resin coating arranged on the surface of the organic phosphonic acid primer coating and having an average thickness of to 100 ?m after drying.

Abstract: The invention relates to an ultrahigh-strength thin steel sheet excellent in the hydrogen embrittlement resistance, the steel sheet including, by weight %, 0.10 to 0.60% of C, 1.0 to 3.0% of Si, 1.0 to 3.5% of Mn, 0.15% or less of P, 0.02% or less of S, 1.5% or less of Al, 0.003 to 2.0% of Cr, and a balance including iron and inevitable impurities; in which grains of residual austenite have an average axis ratio (major axis/minor axis) of 5 or more, the grains of the residual austenite have an average minor axis length of 1 ?m or less, and the grains of the residual austenite have a nearest-neighbor distance between the grains of 1 ?m or less.

Abstract: An aluminium alloy material having an excellent sea water corrosion resistance comprises an aluminium alloy substrate whose ten-points average surface roughness Rz, which is the average of five greatest peak-to-valley separations on the surface, is controlled at 0.3 um or over, an organic phosphonic primer film formed on a surface of the aluminium alloy substrate, and a fluorine resin paint film formed on the primer film and having a dry average thickness of 1 to 100 ?m. A plate heat exchanger having an excellent sea water corrosion resistance is also provided wherein the aluminium alloy material is used as a heat transfer unit using sea water as cooling water.

Abstract: The purpose of the present invention is to provide a high strength thin steel sheet that has high hydrogen embrittlement resisting property. In order to achieve the above purpose, a high strength thin steel sheet having high hydrogen embrittlement resisting property comprises: C: 0.10 to 0.25%; Si: 1.0 to 3.0%; Mn: 1.0 to 3.5%; P: 0.15% or less; S: 0.02% or less; and Al: 1.5% or less (higher than 0%) in terms of percentage by weight, with balance of iron and inevitable impurities; and the metal structure comprises: residual austenite; 1% by area or more in proportion to the entire structure; bainitic ferrite and martensite: 80% or more in total; and ferrite and pearlite: 9% or less (may be 0%) in total, while the mean axis ratio (major axis/minor axis) of said residual austenite grains is 5 or higher, and the steel has tensile strength of 1180 MPa or higher.

Abstract: The present invention provides a high strength thin steel sheet that has high hydrogen embrittlement resisting property and high workability. The high strength thin steel sheet having high hydrogen embrittlement resisting property has a metallurgical structure after stretch forming process to elongate 3% comprises: (i) 1% or more residual austenite; 80% or more in total of bainitic ferrite and martensite; and 9% or less (may be 0%) in total of ferrite and pearlite in terms of proportion of area to the entire structure, wherein the mean axis ratio (major axis/minor axis) of the residual austenite grains is 5 or higher, or (ii) 1% or more residual austenite in terms of proportion of area to the entire structure; mean axis ratio (major axis/minor axis) of the residual austenite grains is 5 or higher; mean length of minor axes of the residual austenite grains is 1 ?m or less; minimum distance between the residual austenite grains is 1 ?m or less; and the steel has tensile strength of 1180 MPa or higher.