Abstract: A ferritic stainless steel sheet comprises: a predetermined chemical composition, wherein a difference between a maximum value and a minimum value of Vickers hardness in a thickness direction is HV 50 or less.

Abstract: A ferritic stainless steel sheet has a predetermined chemical composition and thickness, and has an area ratio of crystal grains of 45 ?m or more in grain size of 20% or less.

Abstract: Provided is a ferritic stainless steel sheet excellent in shape of weld zone and corrosion resistance of a weld zone with a material of a different kind formed by performing welding with austenitic stainless steel. A ferritic stainless steel sheet having a chemical composition containing, by mass %, C: 0.003% to 0.020%, Si: 0.01% to 1.00%, Mn: 0.01% to 0.50%, P: 0.040% or less, S: 0.010% or less, Cr: 20.0% to 24.0%, Cu: 0.20% to 0.80%, Ni: 0.01% to 0.60%, Al: 0.01% to 0.08%, N: 0.003% to 0.020%, Nb: 0.40% to 0.80%, Ti: 0.01% to 0.10%, Zr: 0.01% to 0.10%, and the balance being Fe and inevitable impurities, in which relational expression (1) below is satisfied: 3.0?Nb/(2Ti+Zr+0.5Si+5Al)?1.5??(1), here, in relational expression (1), each of the atomic symbols denotes the content (mass %) of the corresponding chemical element.

Abstract: Provided is a hot-rolled and annealed ferritic stainless steel sheet excellent in surface quality after bending work has been performed. A hot-rolled and annealed ferritic stainless steel sheet has a thickness of 5.0 mm or more and a chemical composition containing, by mass %, C: 0.001% to 0.025%, Si: 0.05% to 0.70%, Mn: 0.05% to 0.50%, P: 0.050% or less, S: 0.01% or less, Cr: 10.0% to 18.0%, Ni: 0.01% to 1.00%, Al: 0.001% to 0.10%, N: 0.001% to 0.025%, Ti: 0.01% to 0.40%, and a balance of Fe and inevitable impurities, in which a difference between maximum and minimum values of an average crystal grain diameter determined by using measuring method 1 is 50 ?m or less, and in which a difference between maximum and minimum values of a crystal grain elongation rate determined by using measuring method 2 is 5.0 or less.

Abstract: A ferritic stainless steel sheet comprises: a predetermined chemical composition, wherein a difference between a maximum value and a minimum value of Vickers hardness in a thickness direction is HV 50 or less.

Abstract: Provided is a hot-rolled and annealed ferritic stainless steel sheet excellent in surface quality after bending work has been performed. A hot-rolled and annealed ferritic stainless steel sheet has a thickness of 5.0 mm or more and a chemical composition containing, by mass %, C: 0.001% to 0.025%, Si: 0.05% to 0.70%, Mn: 0.05% to 0.50%, P: 0.050% or less, S: 0.01% or less, Cr: 10.0% to 18.0%, Ni: 0.01% to 1.00%, Al: 0.001% to 0.10%, N: 0.001% to 0.025%, Ti: 0.01% to 0.40%, and a balance of Fe and inevitable impurities, in which a difference between maximum and minimum values of an average crystal grain diameter determined by using measuring method 1 is 50 ?m or less, and in which a difference between maximum and minimum values of a crystal grain elongation rate determined by using measuring method 2 is 5.0 or less.

Abstract: The present invention provides a ferritic stainless steel sheet and a method for manufacturing the same. A ferritic stainless steel sheet has a composition containing C: 0.001 to 0.020%, Si: 0.05 to 0.35%, Mn: 0.05 to 1.00%, P: 0.04% or less, S: 0.01% or less, Al: 0.001 to 0.300%, Cr: 10.0 to 13.0%, Ni: 0.75 to 1.50%, Ti: 0.05 to 0.35%, and N: 0.001 to 0.020%, with the balance being Fe and inevitable impurities, in which ?I [AD] represented by formula (1) below is 65% or more, and a metal structure has an average crystal grain size of 45 ?m or less: ?I [%]=24Ni+12Mn+6Cu?18Si?12Cr?12Mo+188 (1), where Ni, Mn, Cu, Si, Cr, and Mo represent contents of the respective elements (percent by mass), and an element not contained represents 0.

Abstract: Provided is a ferritic stainless steel sheet excellent in shape of weld zone and corrosion resistance of a weld zone with a material of a different kind formed by performing welding with austenitic stainless steel. A ferritic stainless steel sheet having a chemical composition containing, by mass %, C: 0.003% to 0.020%, Si: 0.01% to 1.00%, Mn: 0.01% to 0.50%, P: 0.040% or less, S: 0.010% or less, Cr: 20.0% to 24.0%, Cu: 0.20% to 0.80%, Ni: 0.01% to 0.60%, Al: 0.01% to 0.08%, N:. 0.003% to 0.020%, Nb: 0.40% to 0.80%, Ti: 0.01% to 0.10%, Zr: 0.01% to 0.10%, and the balance being Fe and inevitable impurities, in which relational expression (1) below is satisfied: 3.0?Nb/(2Ti+Zr+0.5 Si+5 Al)?1.5 ??(1), here, in relational expression (1), each of the atomic symbols denotes the content (mass %) of the corresponding chemical element.

Abstract: A high-strength galvanized steel sheet has a chemical composition containing, by mass %, C: 0.16% or more and 0.24% or less, Si: 0.8% or more and 1.8% or less, Mn: 1.0% or more and 3.0% or less, P: 0.020% or less, S: 0.0040% or less, Al: 0.01% or more and 0.1% or less, N: 0.01% or less, Ca: 0.0001% or more and 0.0020% or less, and the balance including Fe and incidental impurities, and a microstructure, in which the total area ratio of a ferrite phase and a bainite phase with respect to the whole microstructure is 30% or more and 70% or less, in which the area ratio of a tempered martensite phase with respect to the whole microstructure is 20% or more and 40% or less, in which the area ratio of a retained austenite phase with respect to the whole microstructure is 10% or more and 20% or less, and in which the area ratio of a martensite phase with respect to the whole microstructure is 2% or more and 20% or less.

Abstract: There is provided a high-strength steel sheet having a tensile strength (TS) of 900 MPa or more and excellent elongation, stretch flangeability, and bendability in a component system in which an expensive alloy element is not intentionally added. A high-strength steel sheet includes a composition including, on a mass % basis, C: 0.15 to 0.40%, Si: 1.0 to 2.0%, Mn: 1.5 to 2.5%, P: 0.020% or less, S: 0.0040% or less, Al: 0.01 to 0.1%, N: 0.01% or less, and Ca: 0.0020% or less, with the balance including Fe and incidental impurities. The high-strength steel sheet has a microstructure including 40% to 70% of a ferrite phase and a bainite phase in total, 20% to 50% of a martensite phase, and 10% to 30% of a retained austenite phase in terms of an area fraction relative to the entire microstructure.

Abstract: A high-strength galvannealed steel sheet has a chemical composition containing, by mass %, C: 0.14% or more and 0.24% or less, Si: 0.8% or more and 1.8% or less, Mn: 1.0% or more and 3.0% or less, P: 0.020% or less, S: 0.0040% or less, Al: 0.01% or more and 0.1% or less, N: 0.01% or less, Ca: 0.0001% or more and 0.

Abstract: A cold-rolled steel sheet having a steel composition comprising, by mass %, 0.12% to 0.22% C, 0.8% to 1.8% Si, 1.8% to 2.8% Mn, 0.020% or less P, 0.0040% or less S, 0.005% to 0.08% Al, 0.008% or less N, 0.001% to 0.040% Ti, 0.0001% to 0.0020% B, 0.0001% to 0.0020% Ca, and Fe and incidental impurities. The steel sheet includes a microstructure in which ferrite and bainite phases are 50% to 70% of the total area, the average grain size of the ferrite and bainite phase is 1 to 3 ?m, a tempered martensite phase is 25% to 45% of the total area, the average grain size of the tempered martensite phase is 1 to 3 ?m, and a retained austenite phase is 2% to 10% of the total area.

Abstract: A slab has a steel composition including 0.020% to 0.065% of C, 0.1% or less of Si, 0.40% to less than 0.80% of Mn, 0.030% or less of P, 0.005% or less of S, 0.08% to 0.16% of Ti, 0.005% to 0.1% of Al, 0.005% or less of N, and the balance being Fe and incidental impurities, in which Ti*(=Ti?(48/14)×N) satisfies [Ti*?0.08] and [0.300?C/Ti*?0.375], is subjected to hot rolling to obtain a hot-rolled steel sheet in which the steel microstructure includes, in terms of area fraction, 95% or more of a ferrite phase; the average ferrite grain size is 10 ?m or less; the average grain size of Ti carbides precipitated in steel is 10 nm or less; and Ti in the amount of 80% or more of Ti* is precipitated as Ti carbides.

Abstract: A steel sheet has a microstructure including ferrite phase: 40% to 60%, bainite phase: 10% to 30%, tempered martensite phase: 20% to 40%, and retained austenite phase: 5% to 20% by volume fraction, and satisfying a condition that a ratio of tempered martensite phase having major axis length ?5 ?m to a total volume fraction of the tempered martensite phase is 80% to 100%.

Abstract: A high-strength cold-rolled steel sheet having excellent elongation, stretch flangeability, and bendability and a method for producing the same.

Abstract: There is provided a high-strength steel sheet having a tensile strength (TS) of 900 MPa or more and excellent elongation, stretch flangeability, and bendability in a component system in which an expensive alloy element is not intentionally added. A high-strength steel sheet includes a composition including, on a mass % basis, C: 0.15 to 0.40%, Si: 1.0 to 2.0%, Mn: 1.5 to 2.5%, P: 0.020% or less, S: 0.0040% or less, Al: 0.01 to 0.1%, N: 0.01% or less, and Ca: 0.0020% or less, with the balance including Fe and incidental impurities. The high-strength steel sheet has a microstructure including 40% to 70% of a ferrite phase and a bainite phase in total, 20% to 50% of a martensite phase, and 10% to 30% of a retained austenite phase in terms of an area fraction relative to the entire microstructure.

Abstract: A high strength hot-rolled steel sheet with a tensile strength of not less than 590 MPa which exhibits excellent bake hardenability and stretch-flangeability has a chemical composition including, in terms of mass %, C at 0.040 to 0.10%, Si at not more than 0.3%, Mn at 1.7 to 2.5%, P at not more than 0.030%, S at not more than 0.005%, Al at not more than 0.1% and N at 0.006 to 0.025%, and microstructure wherein a bainite phase represents not less than 60%, the total of a ferrite phase and a pearlite phase represents not more than 10%, and the bainite phase includes grains among which cementite grains have been precipitated at not less than 1.4×104 grains/mm2 and the cementite grains have an average grain diameter of not more than 1.5 ?m.

Abstract: A high-strength galvannealed steel sheet has a chemical composition containing, by mass %, C: 0.14% or more and 0.24% or less, Si: 0.8% or more and 1.8% or less, Mn: 1.0% or more and 3.0% or less, P: 0.020% or less, S: 0.0040% or less, Al: 0.01% or more and 0.1% or less, N: 0.01% or less, Ca: 0.0001% or more and 0.

Abstract: A high-strength galvanized steel sheet has a chemical composition containing, by mass %, C: 0.16% or more and 0.24% or less, Si: 0.8% or more and 1.8% or less, Mn: 1.0% or more and 3.0% or less, P: 0.020% or less, S: 0.0040% or less, Al: 0.01% or more and 0.1% or less, N: 0.01% or less, Ca: 0.0001% or more and 0.0020% or less, and the balance including Fe and incidental impurities, and a microstructure, in which the total area ratio of a ferrite phase and a bainite phase with respect to the whole microstructure is 30% or more and 70% or less, in which the area ratio of a tempered martensite phase with respect to the whole microstructure is 20% or more and 40% or less, in which the area ratio of a retained austenite phase with respect to the whole microstructure is 10% or more and 20% or less, and in which the area ratio of a martensite phase with respect to the whole microstructure is 2% or more and 20% or less.

Abstract: A high strength galvanized steel sheet includes a steel sheet which is a base sheet and a galvanized layer on a surface of the steel sheet, the steel sheet has a composition including, by mass %, 0.08 to 0.15% of C, 0.5 to 1.5% of Si, 0.5 to 1.5% of Mn, 0.1% or less of P, 0.01% or less of S, 0.01 to 0.1% of Al, 0.005% or less of N, and the balance Fe with inevitable impurities, and a microstructure composed of 75 to 90% of a ferrite phase as a main phase and 10 to 25% of a second phase including at least pearlite in terms of an area fraction with respect to the entire microstructure; an average grain size of the pearlite is 5 ?m or smaller; and the pearlite has an area fraction of 70% or greater with respect to the total area of the second phase.