Abstract: Provided is an abrasion-resistant steel plate excellent in both abrasion resistance and wide bending workability. An abrasion-resistant steel plate comprises a specific chemical composition, wherein a volume fraction of martensite at a depth of 1 mm from a surface of the abrasion-resistant steel plate is 90 % or more, hardness at a depth of 1 mm from the surface is 500 HBW 10/3000 to 650 HBW 10/3000 in Brinell hardness, and a transverse direction hardness difference is 30Hv10 or less in Vickers hardness, the transverse direction hardness difference being defined as a difference in the hardness at a depth of 1 mm from the surface between two points adjacent at intervals of 10 mm in a transverse direction of the abrasion-resistant steel plate.

Abstract: Provided is an abrasion-resistant steel plate excellent in both abrasion resistance and wide bending workability. An abrasion-resistant steel plate comprises a specific chemical composition, wherein a volume fraction of martensite at a depth of 1 mm from a surface of the abrasion-resistant steel plate is 90% or more, a number density of TiC precipitates of 0.5 ?m or more in equivalent circular diameter at a depth of 1 mm from the surface is 400/mm2 or more, hardness at a depth of 1 mm from the surface is 360 HBW 10/3000 or more in Brinell hardness, and a transverse direction hardness difference is 30Hv10 or less in Vickers hardness, the transverse direction hardness difference being defined as a difference in the hardness at a depth of 1 mm from the surface between two points adjacent at intervals of 10 mm in a transverse direction of the abrasion-resistant steel plate.

Abstract: Provided is a steel pipe for a linepipe having high compressive strength, a heavy wall thickness and sour gas resistance. The steel pipe has the composition which contains by mass % 0.02 to 0.06% C, 0.01 to 0.5% Si, 0.8 to 1.6% Mn, 0.012% or less P, 0.0015% or less S, 0.01 to 0.08% Al, 0.005 to 0.050% Nb, 0.005 to 0.025% Ti, 0.0005 to 0.0035% Ca, 0.0020 to 0.0060% N, and Fe and unavoidable impurities as a balance. The steel pipe has metal microstructure where a fraction of bainite is 80% or more, a fraction of M-A constituent is 2% or less and an average grain size of bainite is 5 ?m or less.

Abstract: A stainless cladding steel plate with excellent sea water corrosion resistance includes a cladding metal including, in mass %, C: not more than 0.030%, Si: 0.02 to 1.50%, Mn: 0.02 to 2.0%, P: not more than 0.040%, S: not more than 0.030%, Ni: 22.0 to 25.0%, Cr: 22.0 to 26.0%, Mo: 3.5 to 5.0% and N: 0.10 to 0.25%, the balance being Fe and inevitable impurities, the cladding metal satisfying relation (1) and being such that amounts of chromium and molybdenum present as precipitates are not more than 0.3 mass % and not more than 0.2 mass %, respectively, Cr+3.3Mo+16N?40 ??(1) wherein chemical symbols indicate amounts in mass % of the respective elements.

Abstract: Provided are a steel pipe for a linepipe with high compressive strength and a heavy wall thickness, and a method of manufacturing the same. Lowering of yield stress caused by a Bauschinger effect can be suppressed by optimizing the metal microstructure of a steel plate without requiring particular forming conditions in forming the steel pipe, and without requiring heat treatment after pipe making. A steel pipe has the composition which contains by mass % 0.03 to 0.10% C, 0.30% or less Si, 1.00 to 2.00% Mn, 0.015% or less P, 0.003% or less S, 0.080% or less Al, 0.005 to 0.035% Nb, 0.005 to 0.020% Ti, and Fe and unavoidable impurities as a balance. The steel pipe has metal microstructure where a fraction of bainite is 60% or more, a fraction of rolled ferrite is 5% or less, and a fraction of M-A constituent (MA) is 3% or less.

Abstract: A base metal for high-toughness clad plate having excellent toughness at a welded joint contains, in terms of mass %, C: 0.030 to 0.10%, Si: 0.10 to 0.30%, Mn: 1.00 to 1.60%, P: 0.015% or less, S: 0.003% or less, V: less than 0.010%, and at least one selected from Mo: 0.05 to 0.50%, Nb: 0.010 to 0.060%, Ti: 0.005 to 0.020%, Al: 0.040% or less, Ca: 0.0010 to 0.0040%, and N: 0.0030 to 0.0060%, the balance being Fe and unavoidable impurities, in which a percent ductile fracture is 85% or more in a ?20° C. DWTT test and vE?20° C. is 100 J or more at a HAZ 3 mm position.

Abstract: Provided is a steel pipe for a linepipe having high compressive strength, a heavy wall thickness and sour gas resistance. The steel pipe has the composition which contains by mass % 0.02 to 0.06% C, 0.01 to 0.5% Si, 0.8 to 1.6% Mn, 0.012% or less P, 0.0015% or less S, 0.01 to 0.08% Al, 0.005 to 0.050% Nb, 0.005 to 0.025% Ti, 0.0005 to 0.0035% Ca, 0.0020 to 0.0060% N, and Fe and unavoidable impurities as a balance. The steel pipe has metal microstructure where a fraction of bainite is 80% or more, a fraction of M-A constituent is 2% or less and an average grain size of bainite is 5 ?m or less.

Abstract: Provided are a steel pipe for a linepipe having a heavy wall thickness and excellent fracture toughness in a base material, and methods of producing the same. A welded heat affected zone is achieved by suppressing lowering of yield stress caused by a Bauschinger effect by optimizing the metal microstructure of a steel plate. A steel pipe has a composition which contains by mass % 0.03 to 0.08% C, 0.10% or less Si, 1.00 to 2.00% Mn, 0.010% or less P, 0.0030% or less S, 0.06% or less Al, 0.005 to 0.020% Nb, 0.005 to 0.025% Ti, 0.0010 to 0.0060% N, and Fe and unavoidable impurities as a balance. Ti(%)/N(%) is a value which falls within a range of 2 to 4, and a Ceq value is 0.30 or more.

Abstract: Provided are a steel pipe for a linepipe with high compressive strength and a heavy wall thickness, and a method of manufacturing the same. Lowering of yield stress caused by a Bauschinger effect can be suppressed by optimizing the metal microstructure of a steel plate without requiring particular forming conditions in forming the steel pipe, and without requiring heat treatment after pipe making. A steel pipe has the composition which contains by mass % 0.03 to 0.10% C, 0.30% or less Si, 1.00 to 2.00% Mn, 0.015% or less P, 0.003% or less S, 0.080% or less Al, 0.005 to 0.035% Nb, 0.005 to 0.020% Ti, and Fe and unavoidable impurities as a balance. The steel pipe has metal microstructure where a fraction of bainite is 60% or more, a fraction of rolled ferrite is 5% or less, and a fraction of M-A constituent (MA) is 3% or less.