Abstract: A hot-dip galvanized steel sheet includes: a predetermined chemical composition; and a steel structure represented by: in terms of area ratio, polygonal ferrite: 10% or less; upper bainite: 20% or less; retained austenite: 5% or less; and martensite: 70% or more, in which: martensite having Fe carbides at a number density of 1×106/mm2 or more is contained by 50% or more, in terms of area ratio, with respect to the entire amount of martensite; and the steel structure has an average effective crystal grain diameter of 5.0 ?m or less.

Abstract: There is provided a high strength hot rolled steel sheet including a predetermined chemical composition. A structure includes, by area ratio, 80% or more of polygonal ferrite, a total of 5% or less of martensite and austenite, and a total of 5% or less of pearlite and cementite, and a remainder is at least one selected from bainitic ferrite and bainite. When a standard deviation of micro-hardness of 50 arbitrary pieces of the polygonal ferrite present within a range of ±100 ?m from a central plane in a sheet thickness direction is ?HV, the ?HV is 30 or smaller. A grain of the polygonal ferrite contains 5×107 pieces/mm2 or more of Ti-containing carbide, and in 50% or more of the Ti-containing carbide, the aspect ratio which is a ratio of a length of a long side to a length of a short side is less than 3. The tensile strength is 540 MPa or higher.

Abstract: A high-strength cold-rolled steel sheet is provided that has a chemical composition that consists of, by mass %, C: 0.050 to 0.40%, Si: 0.01 to 3.0%, Mn: 1.0 to 5.0%, sol. Al: 0.001 to 1.0%, Ti: 0.005 to 0.20%, B: 0.0005 to 0.010%, P: 0.1% or less, S: 0.01% or less, O: 0.1% or less, N: 0.01% or less, Cr: 0 to 1.0%, Mo: 0 to 1.0%, Ni: 0 to 1.0%, Cu: 0 to 1.0%, Sn: 0 to 0.50%, Nb: 0 to 0.20%, V: 0 to 0.50%, W: 0 to 0.50%, Ca: 0 to 0.01%, Mg: 0 to 0.01%, Bi: 0 to 0.01%, Sb: 0 to 0.10%, Zr: 0 to 0.01%, and REM: 0 to 0.01%, with the balance being Fe and impurities, and that satisfies the formulas [sol. Bs/B?0.50] and [sol. Bq/B>0.50] (where, B: B amount in the steel; sol. Bs: soluble B amount in a surface layer portion of the steel; and sol. Bq: soluble B amount in the steel interior).

Abstract: A high-strength steel sheet includes a specific chemical composition, and a microstructure represented by, in area %, martensite: 5% or more; ferrite: 20% or more; and perlite: 5% or less. An average diameter of martensite grain is 4 ?m or less in equivalent circle diameter. A ratio of the number of bulging type martensite grains to the number of martensite grains on grain boundary triple points of a matrix is 70% or more, wherein: the bulging type martensite grain is on one of the grain boundary triple points of the matrix; and at least one of grain boundaries of the bulging type martensite grain, the grain boundaries connecting two adjacent grain boundary triple points of the bulging type martensite grain and grains of the matrix, has a convex curvature to an outer side with respect to line segments connecting the two adjacent grain boundary triple points. An area ratio represented by VM/A0 is 1.

Abstract: A hot-rolled steel sheet according to the present embodiment has a chemical composition containing, in mass %: C: 0.07 to 0.30%, Si: more than 1.0 to 2.8%, Mn: 2.0 to 3.5%, P: 0.030% or less, S: 0.010% or less, Al: 0.01 to less than 1.0%, N: 0.01% or less, O: 0.01% or less, and one or more types selected from the group consisting of Sb, Sn and Te in a total amount of 0.03 to 0.30%, with a balance being Fe and impurities, and satisfying Formula (1). The micro-structure of the hot-rolled steel sheet includes ferrite and pearlite in a total amount of 50 area % or more. The tensile strength of the hot-rolled steel sheet is 900 MPa or less. Si+Mn?3.20??(1) Where, a content (mass %) of a corresponding element is substituted for each symbol of an element in Formula (1).

Abstract: In a high strength hot-dip galvannealed hot-rolled steel sheet that has an excellent hole expansibility suitable for a stretch flanging and preferably has a high yield ratio and a tensile strength of at least 650 MPa, a hot-rolled steel sheet used as a base material for plating has a chemical composition comprising: in mass %, C: from at least 0.01 and at most 0.20%; Si: at most 0.50%; Mn: from at least 0.01% to at most 1.30%; P: at most 0.05%; S: at most 0.01%; N: at most 0.01%; Al: at most 0.50%; and Ti: from at least 0.05% to at most 0.50%, and a steel structure consisting of a polygonal ferrite having at least 80 area % and the remainder containing one kind or two or more kinds selected from bainitic ferrite, bainite, pearlite, and cementite.

Abstract: A process of producing a hydrophobic organosilica sol which comprises aging a reaction mixture at 0 to 100.degree. C. in the state that an alkali present in the reaction mixture is removed or is neutralized with an acid in an equivalent amount or more, thereby forming a silylation-treated silica sol having a hydrophobic colloidal silica dispersed therein, the reaction mixture comprising: (a) a hydrophilic colloidal silica having a specific surface area of 5.5 to 550 m.sup.2 /g in SiO.sub.2 concentration of 5 to 55% by weight, (b) a silylating agent of a disiloxane compound and/or monoalkoxysilane compound in a millimolar ratio of 0.03 to 2 in terms of Si atom per 100 m.sup.2 of a surface of the hydrophilic colloidal silica, and (c) a medium, as a residue thereof, comprising a mixed solvent comprising a hydrophobic organic solvent having a solubility of water of 0.1 to 12% by weight and an alcohol having 1 to 3 carbon atoms in a weight ratio of 0.

Abstract: A propanol sol of silica having a specific surface area of 25 to 550 m.sup.2 /g, the sol having an SiO.sub.2 concentration of 10 to 50% by weight of SiO.sub.2 and a residual content of a medium containing 7.5% by weight or less of water based on the SiO.sub.2 content and 90% by weight or more of propanol, is prepared by an improved process involving replacing the aqueous medium in an acidic aqueous sol of silica containing 5 to 50% by weight of SiO.sub.2 and a medium having a water content of 15% by weight or more with propanol by an atmospheric distillation method in which a concentration of 5 to 50% by weight of SiO.sub.2 in the sol and 1 to 85% by weight of methanol in the medium in the sol is maintained when the medium in the sol during the replacement contains 15 to 0.5% by weight of water.