Abstract: There are provided a high-strength hot-rolled steel sheet securing low-temperature toughness and having excellent stretch flangeability by controlling a structural fraction and a hardness difference among structures, and a manufacturing method thereof. A hot-rolled steel sheet contains: C: 0.01 to 0.2%; Si: 0.001 to 2.5% or less; Mn: 0.10 to 4.0% or less; P: 0.10% or less; S: less than 0.03%; Al: 0.001 to 2.0%; N: less than 0.01%; Ti: (0.005+48/14[N]+48/32[S]) % or more and 0.3% or less; Nb: 0 to 0.06%; Cu: 0 to 1.2%; Ni: 0 to 0.6%; Mo: 0 to 1%; V: 0 to 0.2%; Cr: 0 to 2%; Mg: 0 to 0.01%; Ca: 0 to 0.01%; REM: 0 to 0.1%; and B: 0 to 0.002%, and has: an texture in which, at a central portion of a sheet thickness located between ? to ? thickness positions of the sheet thickness from a surface of the steel sheet, an average value of X-ray random intensity ratios of a group of {100}<011> to {223}<110> orientations of a sheet plane is 6.

Abstract: A high-strength cold-rolled steel sheet having excellent stretch flangeability and precision punchability containing predetermined components and a balance being composed of iron and inevitable impurities, in which in a range of ? to ? in sheet thickness from the surface of the steel sheet, an average value of pole densities of the {100}<011> to {223}<110> orientation group represented by respective crystal orientations of {100}<011>, {116}<110>, {114}<110>, {113}<110>, {112}<110>, {335}<110>, and {223}<110> is 6.5 or less, and a pole density of the {332}<113> crystal orientation is 5.0 or less, and a metal structure contains, in terms of an area ratio, greater than 5% of pearlite, the sum of bainite and martensite limited to less than 5%, and a balance composed of ferrite.

Abstract: In a hot-rolled steel sheet, an average pole density of an orientation group of {100}<011> to {223}<110>, which is represented by an arithmetic average of pole density of each orientation of {100}<011>, {116}<110>, {114}<110>, {112}<110>, and {223}<110> in a center portion of a sheet thickness which is a range of the sheet thickness of ? to ? from a surface of the steel sheet, is 1.0 or more and 4.0 or less, the pole density of a crystal orientation of {332}<113> is 1.0 or more and 4.8 or less, an average grain size in a center in the sheet thickness is 10 ?M or less, and a microstructure includes, by a structural fraction, pearlite more than 6% and ferrite in the balance.

Abstract: In a hot-rolled steel sheet, an average pole density of an orientation group {100}<011> to {223}<110>, which is represented by an arithmetic mean of pole densities of orientations {100}<011>, {116}<110>, {114}<110>, {112}<110>, and {223}<110> is 1.0 to 4.0 and a pole density of a crystal orientation {332}<113> is 1.0 to 4.8, in a thickness center portion which is a thickness range of ? to ? from the surface of the steel sheet; an average grain size in the thickness center portion is less than or equal to 10 ?m and a grain size of cementite precipitating in a grain boundary of the steel sheet is less than or equal to 2 ?m; and an average grain size of precipitates containing TiC in grains is less than or equal to 3 nm and a number density per unit volume is greater than or equal to 1×1016 grains/cm3.

Abstract: The present invention provides a bainite-containing-type high-strength hot-rolled steel sheet. The steel sheet, containing C: greater than 0.07 to 0.2%, Si: 0.001 to 2.5%, Mn: 0.01 to 4%, P: 0.15% or less, S: 0.03% or less, N: 0.01% or less, Al: 0.001 to 2% and a balance being composed of Fe and impurities, has an average value of pole densities of the {100}<011> to {223}<110> orientation group at a sheet thickness center portion being a range of ? to ? in sheet thickness from the surface of the steel sheet is 4.0 or less, and a pole density of the {332}<113> crystal orientation is 4.8 or less, an average crystal grain diameter is 10 ?m or less and vTrs is ?20° C. or lower, and a microstructure is composed of 35% or less in a structural fraction of pro-eutectoid ferrite and a balance of a low-temperature transformation generating phase.

Abstract: This invention provides a branched polycarbonate resin obtained from a dihydric phenol compound, a branching agent, monohydric phenols and phosgene by an interfacial polymerization reaction method in the presence of an alkali aqueous solution and an organic solvent, the branched polycarbonate resin having features that: (i) the branching agent content (X) thereof is over 0.70 mol % but 1.50 mol % or less, (ii) the branching agent content (X) and the melt tension (Y) thereof at 280° C. satisfy the following expression (1), 3.8X?2.4?Y?3.8X+4.5 (1), and (iii) the entire N content in the branched polycarbonate resin is 0 to 7 ppm.

Abstract: A resin composition comprising an aromatic polycarbonate resin having excellent transparency and flame retardancy. The resin composition comprises 100 parts by weight of an aromatic polycarbonate resin having a branched structure with a branching ratio of 0.7 to 1.1 mol % (component A) and 0.005 to 12 parts by weight of at least one flame retardant.

Abstract: A resin composition comprising an aromatic polycarbonate resin and having excellent transparency and flame retardancy. The resin composition comprises 100 parts by weight of the aromatic polycarbonate resin having a branched structure with a branching ratio of 0.7 to 1.1 mol % (component A) and 0.005 to 12 parts by weight of a flame retardant.

Abstract: The invention seeks to provide a branched polycarbonate resin having a high branching agent content, which has a good melt tension, virtually causes no drawdown and permits stable molding when it is molded in extrusion molding, blow molding, injection molding, vacuum molding, etc., and a process for producing the same. This invention provides a branched polycarbonate resin obtained from a dihydric phenol compound, a branching agent, monohydric phenols and phosgene by an interfacial polymerization reaction method in the presence of an alkali aqueous solution and an organic solvent, the branched polycarbonate resin having features that: (i) the branching agent content (X) thereof is over 0.70 mol % but 1.50 mol % or less, (ii) the branching agent content (X) and the melt tension (Y) thereof at 280° C. satisfy the following expression (1), 3.8X?2.4?Y—3.8X+4.5??(1), and (iii) the entire N content in the branched polycarbonate resin is 0 to 7 ppm.

Abstract: There are provided a polycarbonate copolymer (A) which has excellent light resistance and heat resistance and comprises an aromatic dihydroxy component comprising 5 to 95 mol % of fluorene-skeleton-containing dihydroxy compound (1) having a specific structure and 95 to 5 mol % of ordinary bisphenol type dihydroxy compound (2), the content of fluorene-9-one in the copolymer being not higher than 15 ppm; and a polycarbonate composition comprising 0.01 to 5 parts by weight of ultraviolet absorber (B) based on 100 parts by weight of the copolymer (A), and the composition comprising the copolymer.

Abstract: There are provided a polycarbonate copolymer (A) which has excellent light resistance and heat resistance and comprises an aromatic dihydroxy component comprising 5 to 95 mol % of fluorene-skeleton-containing dihydroxy compound (1) having a specific structure and 95 to 5 mol % of ordinary bisphenol type dihydroxy compound (2), the content of fluorene-9-one in the copolymer being not higher than 15 ppm; and a polycarbonate composition comprising 0.01 to 5 parts by weight of ultraviolet absorber (B) based on 100 parts by weight of the copolymer (A), and the composition comprising the copolymer.