Abstract: Provided are a hot dip galvanized steel sheet having a predetermined chemical composition, and a steel microstructure comprising, by vol %, ferrite: 0 to 50%, tempered martensite: 1% or more, retained austenite: 5% or more, fresh martensite: 0 to 15%, total of pearlite and cementite: 0 to 5%, and balance: bainite, when measuring by GDS, a maximum value of Al concentration of an Al rich layer present at an interface of the base steel sheet and the hot dip galvanized layer is 2.0 mass % or more and an Sis/Sib right under the interface is 0.90 or less, a number density of recessed parts with a depth of more than 2 ?m at the interface is 2.0/100 ?m or less per interface length, and a tensile strength is 980 MPa or more, and a method for producing the same.

Abstract: This steel sheet has a predetermined chemical composition, a tensile strength is 780 MPa or greater, a total of the area ratio of ferrite and an area ratio of bainite is 10% or greater and 90% or less, a total of an area ratio of martensite and an area ratio of tempered martensite is 10% or greater and 90% or less, and a total of an area ratio of pearlite and an area ratio of residual austenite is 0% or greater and 10% or less, a number proportion of crystal grains of ferrite and bainite having an area of 6 ?m2 or less is 40% or greater to a total number of crystal grains of the ferrite and the bainite, and a number proportion of crystal grains of ferrite and bainite having an area of 50 ?m2 or greater is 5% or less to the total number of crystal grains of the ferrite and the bainite, and a maximum Mn content in a region up to 0.

Abstract: Provided are a steel sheet having a predetermined chemical composition, and a steel microstructure comprising, by vol %, ferrite: 1 to 50%, ratio of nonrecrystallized ferrite in the ferrite: 0 to 50%, tempered martensite: 1% or more, retained austenite: 5% or more, fresh martensite: 0 to 10%, total of pearlite and cementite: 0 to 5%, and balance: bainite, and, when analyzing the surface by an EPMA, an area ratio of regions with an AlS/SiS ratio of 0.2 or less is 50% or less, and a tensile strength is 980 MPa or more, and a method for producing the same.

Abstract: A scroll compressor includes a movable scroll, a fixed scroll having a suction passage, a suction pipe, and a suction check valve to open and close an open end of the suction pipe. The suction check valve includes a valve body, a valve seat, and a compression spring to bias the valve body toward the open end of the suction pipe. The valve body includes a first bottom portion, and a first circumferential wall extending toward the valve seat along a peripheral portion of the first bottom portion. The valve seat includes a second bottom portion, and a second circumferential wall extending toward the valve body along a peripheral portion of the second bottom portion. One of the first and second circumferential walls has an outside diameter smaller than an inside diameter of an open end of the other one of the first and second circumferential walls.

Abstract: A cold rolled steel sheet having a predetermined chemical composition, and a steel microstructure comprising, by area %, martensite: 90.0 to 99.5%, ferrite: 0 to 5%, retained austenite: 0.5 to 7.0%, and balance: bainite wherein a ratio of tempered martensite to the total martensite is 80 to 100%, a maximum value of curvature 1/R obtained by measuring the shape at a total width×length 300 mm region and expressed by the following formula (1) is 0.010 or less, and a tensile strength of 1470 MPa or more: 1 / R = MAX ? { ? "\[LeftBracketingBar]" ? 1 ? "\[RightBracketingBar]" , ? "\[LeftBracketingBar]" ? 2 ? "\[RightBracketingBar]" } .

Abstract: Provided are a hot dip galvanized steel sheet comprising a base steel sheet wherein the base steel sheet has a predetermined composition and contains ferrite: 0% to 50%, retained austenite: 0% to 30%, tempered martensite: 5% or more, fresh martensite: 0% to 10%, and pearlite and cementite in total: 0% to 5%, remaining structures consist of bainite, when defining a region having a hardness of 90% or less of the hardness at a position of ¼ thickness to the base steel sheet side from an interface of the base steel sheet and a hot dip galvanized layer as a “soft layer”, there is a soft layer having a thickness of 10 ?m or more at the base steel sheet side from the interface, the soft layer contains tempered martensite, and an increase rate in a thickness direction of an area % of tempered martensite from the interface to the inside of the base steel sheet inside the soft layer is 5.0%/?m or less, and a method for producing the same.

Abstract: A hot dip galvanized steel sheet includes a base steel sheet and a hot dip galvanized layer on at least one surface of the base metal steel sheet, wherein the base steel sheet has a predetermined chemical composition, and contains, by volume fraction, ferrite: 0% to 50%, retained austenite: 0% to 30%, tempered martensite: 5% or more, fresh martensite: 0% to 10%, and pearlite and cementite in total: 0% to 5%, when there are remaining structures, the remaining structures consist of bainite, a concentration of B atoms at prior austenite grain boundaries is 2.0 atm % or more, and an average effective crystal grain size is 7.0 ?m or less, and a method for producing the same.

Abstract: Provided are: a steel sheet having a high strength and excellent hydrogen embrittlement resistance; and a method of producing the same. The steel sheet has prescribed chemical composition and structure, in which a standard deviation ? of Mn concentration satisfies ??0.15 Mnave (wherein, Mnave represents an average Mn concentration) and a region with a Mn concentration of higher than (Mnave+1.3?) has a circle-equivalent diameter of less than 10.0 ?m. The method of producing the steel sheet includes: the hot rolling step that includes finish rolling a slab having a prescribed chemical composition under prescribed conditions; the step of coiling the thus obtained hot-rolled steel sheet at a coiling temperature of 450 to 700° C.; and the step of cold rolling the hot-rolled steel sheet and subsequently annealing this steel sheet at 800 to 900° C.

Abstract: A hot dip galvanized steel sheet includes a base steel sheet and a hot dip galvanized layer on at least one surface of the base metal steel sheet, wherein the base steel sheet has a predetermined chemical composition, and contains, by volume fraction, ferrite: 0% to 50%, retained austenite: 0% to 30%, tempered martensite: 5% or more, fresh martensite: 0% to 10%, and pearlite and cementite in total: 0% to 5%, when there are remaining structures, the remaining structures consist of bainite, a concentration of B atoms at prior austenite grain boundaries is 2.0 atm % or more, and an average effective crystal grain size is 7.0 ?m or less, and a method for producing the same.

Abstract: A high-strength steel sheet includes a chemical composition including: by mass %, C: 0.080 to 0.500%, Si: 2.50% or less, Mn: 0.50 to 5.00%, P: 0.100% or less, S: 0.0100% or less, Al: 0.001 to 2.500%, N: 0.0150% or less, O: 0.0050% or less, and the balance: Fe and inevitable impurities. The high-strength steel sheet satisfying a predetermined formula has a microstructure in a region from ?t to ?t from a steel sheet surface. The microstructure includes: by volume %, 20% or more of acicular ferrite, 20% or more of an island-shaped hard structure including residual austenite, 2% to 25% of residual austenite, and 20% or less of aggregated ferrite.

Abstract: A zinc-plated steel sheet includes a steel sheet having a predetermined chemical composition and a zinc-plated layer. In the steel sheet, steel microstructures in a range of ? thickness to ? thickness, having the center at ¼ thickness from a steel sheet surface, include, by vol %, ferrite: 0% to 10%, bainite: 0% to 30%, tempered martensite: 50% or more, fresh martensite: 0% to 10%, retained austenite: more than 10% and 30% or less, and pearlite: 0% to 5%. In the zinc-plated steel sheet, the amount of hydrogen emitted when the steel sheet is heated to 200° C. from room temperature after removal of the zinc-plated layer is 0.40 ppm or less per mass of the steel sheet, the tensile strength is 1470 MPa or more, and no cracking occurs in a U-shape bending test where a stress equivalent to 1000 MPa is applied for 24 hours.

Abstract: Provided are a steel sheet having a predetermined chemical composition, and a steel microstructure comprising, by vol %, ferrite: 1 to 50%, ratio of nonrecrystallized ferrite in the ferrite: 0 to 50%, tempered martensite: 1% or more, retained austenite: 5% or more, fresh martensite: 0 to 10%, total of pearlite and cementite: 0 to 5%, and balance: bainite, and, when analyzing the surface by an EPMA, an area ratio of regions with an AlS/SiS ratio of 0.2 or less is 50% or less, and a tensile strength is 980 MPa or more, and a method for producing the same.

Abstract: Provided are a hot dip galvanized steel sheet comprising a base steel sheet and a hot dip galvanized layer on at least one surface of the base metal steel sheet, wherein the base steel sheet has a predetermined chemical composition and contains, by volume fraction, ferrite: 0% to 50%, retained austenite: 6% to 30%, bainite: 5% or more, tempered martensite: 5% or more, fresh martensite: 0% to 10%, and pearlite and cementite in total: 0% to 5%, a number density of tempered martensite with a circle equivalent diameter of 5.0 ?m or more is 20/1000 ?m2 or less, and an area ratio of fresh martensite with a circle equivalent diameter of 2.0 ?m or more after imparting 5% plastic strain is 10% or less, and a method for producing the same.

Abstract: This steel sheet has a predetermined chemical composition, in which a microstructure at a ¼ depth position of a sheet thickness from a surface of the steel sheet contains, by volume fraction, ferrite: 0% to 50%, residual austenite: 6% to 30%, bainite: 5% to 60%, tempered martensite: 5% to 50%, fresh martensite: 0% to 10%, and pearlite: 0% to 5%, at the ¼ depth position of the sheet thickness from the surface, a number proportion of the residual austenite having an aspect ratio of 2.0 or more to an entire residual austenite is 50% or more, and a number density of inclusions and precipitates having a grain size of 1 ?m or more is 30/mm2 or less, and at a 1/20 depth position of the sheet thickness from the surface, an average interval between Mn-concentrated portions in a direction perpendicular to a rolling direction is 300 ?m or less, and a standard deviation of Mn concentrations in the residual austenite is 0.40% or less.

Abstract: Provided are: a steel sheet having a high strength and excellent stretch formability; and a method of producing the same. The steel sheet has prescribed chemical composition and structure, in which the integration degree of the (111)<112> orientation of ferrite is 3.0 or higher, and the integration degree of the (252)<2-11> orientation of martensite and tempered martensite is 5.0 or lower. The method of producing the steel sheet includes: the step of continuously casting a molten steel having the prescribed chemical composition, and performing 5 to 40% rolling reduction at a temperature of 800° C. to lower than 1,200° C. in a period after the continuous casting until cooling to room temperature; the hot rolling step of performing hot rolling with a finishing temperature of 650 to 950° C.; the step of coiling the resulting hot-rolled steel sheet at a coiling temperature of 400 to 700° C.; the step of retaining the hot-rolled steel sheet at (coiling start temperature+20° C. to 100° C.

Abstract: A zinc-plated steel sheet of an aspect of the present invention includes a steel sheet having a predetermined chemical composition and a zinc-plated layer. In the steel sheet, steel microstructures in a range of ? thickness to ? thickness, having the center at ¼ thickness from a steel sheet surface, include, by vol %, ferrite: 0% to 10%, bainite: 0% to 20%, tempered martensite: 70% or more, fresh martensite: 0% to 10%, retained austenite: 0% to 10%, and pearlite: 0% to 5%. In the zinc-plated steel sheet, the amount of hydrogen emitted when the steel sheet is heated to 200° C. from a room temperature after removal of the zinc-plated layer is 0.40 ppm or less per mass of the steel sheet, the tensile strength is 1470 MPa or more, and no cracking occurs in a U-shape bending test where a stress equivalent to 1000 MPa is applied for 24 hours.

Abstract: This steel sheet has a predetermined chemical composition, in which a steel structure of an inside of the steel sheet contains, by volume fraction, soft ferrite: 0% to 30%, retained austenite: 3% to 40%, fresh martensite: 0% to 30%, a sum of pearlite and cementite: 0% to 10%, and a remainder includes hard ferrite, a number proportion of the retained austenite having an aspect ratio of 2.0 or more in the total retained austenite is 50% or more, a soft layer having a thickness of 1 to 100 ?m from a surface in a sheet thickness direction is present, in ferrite contained in the soft layer, a volume fraction of grains having an aspect ratio of 3.0 or more is 50% or more, a volume fraction of retained austenite in the soft layer is 80% or less of the volume fraction of the retained austenite in the inside of the steel sheet, and a peak of an emission intensity at a wavelength indicating Si appears in a range of more than 0.2 ?m and 10.0 ?m or less from the surface.

Abstract: A steel sheet wherein a steel structure of an inside of the steel sheet contains, by volume fraction, soft ferrite: 0% to 30%, retained austenite: 3% to 40%, fresh martensite: 0% to 30%, a sum of pearlite and cementite: 0% to 10%, and a remainder including hard ferrite. In the steel sheet, in a ? to ? thickness range, a proportion of retained austenite having an aspect ratio of 2.0 or more is 50% or more, and a soft layer having a thickness of 1 to 100 ?m from a surface in a sheet thickness direction is present. When an emission intensity at a wavelength indicating Si is analyzed in the sheet thickness direction from the surface by a radio-frequency glow discharge analysis method, a peak of the emission intensity appears in a range of more than 0.2 ?m and 5.0 ?m or less from the surface.

Abstract: Provided are: a steel sheet having a high strength and excellent hydrogen embrittlement resistance; and a method of producing the same. The steel sheet has prescribed chemical composition and structure, in which a standard deviation ? of Mn concentration satisfies ??0.15 Mnave (wherein, Mnave represents an average Mn concentration) and a region with a Mn concentration of higher than (Mnave+1.3?) has a circle-equivalent diameter of less than 10.0 ?m. The method of producing the steel sheet includes: the hot rolling step that includes finish rolling a slab having a prescribed chemical composition under prescribed conditions; the step of coiling the thus obtained hot-rolled steel sheet at a coiling temperature of 450 to 700° C.; and the step of cold rolling the hot-rolled steel sheet and subsequently annealing this steel sheet at 800 to 900° C.

Abstract: Provided are a steel sheet having a predetermined chemical composition and having the following steel structure, and a method of manufacturing the steel sheet. (1) In area ratio %, ferrite: 0 to 5%, martensite: 90 to 100%, a ratio of tempered martensite to total martensite: 80 to 100%, and retained austenite: 0.5 to 6.0% are contained. (2) The number density of inclusions satisfying the maximum diameter?3 ?m is 40 inclusions/mm2 or less. (3) When the number density of the inclusions satisfying the maximum diameter?3 ?m in each section is calculated, the number density in the section where the number density of inclusions is in the top 10% is 80 inclusions/mm2 or less. (4) Formula (A) is satisfied. V??/V??0.1??(A) V?: Initial retained austenite, V??: Retained austenite after deep cooling at ?196° C. (5) The tensile strength is 1470 MPa or more.