Provided is an HPF member having excellent bending characteristics and a hot-dip aluminum plated layer formed on a surface of a base steel sheet. The base steel sheet includes, in terms of wt %, 0.18-0.25% of C, 0.1-0.5% of Si, 0.9-1.5% of Mn, 0.03% or less of P, 0.01% or less of S, 0.01-0.05% of Al, 0.05-0.5% of Cr, 0.01-0.05% of Ti, 0.001-0.005% of B, 0.009% or less of N, the balance Fe and other impurities; a ferrite phase having a thickness within 50 m is continuously or discontinuously formed inside a surface portion of the base steel sheet; the fraction of the surface portion occupied by the ferrite phase is 5% or less; and carbide materials having a size of 1 m or less are scattered and distributed in the surface portion of the base steel sheet so as to occupy 90% or more of the overall carbide distribution.

A method for producing a coated steel sheet by reheating a steel slab containing 0.15-0.25 wt % of carbon (C), more than 0 wt % but not more than 1.5 wt % of silicon (Si), 1.5-2.5 wt % of manganese (Mn), more than 0 wt % but not more than 1.8 wt % of aluminum (Al), 0.3-1.0 wt % of chromium (Cr), more than 0 wt % but not more than 0.03 wt % of titanium (Ti), more than 0 wt % but not more than 0.03 wt % of niobium (Nb), and the balance of iron (Fe) and unavoidable impurities. Hot-rolling, cooling and coiling the steel slab, thereby producing a hot-rolled steel sheet. Pickling the hot-rolled steel sheet, then cold rolling. Annealing the cold-rolled steel sheet at a temperature between 820 C. and 870 C., followed by cooling at a finish-cooling temperature between 350 C. and 450 C.; tempering the cooled steel sheet at a temperature between 450 C. and 550 C.; and hot-dip galvanizing the tempered steel sheet.

The invention relates to a method for producing a hot-rolled strip composed of a bainitic multi-phase steel and having a ZnMgAl coating, comprising the following steps: melting a steel melt containing (in weight percent): C: 0.04-0.11, Si: <=0.7, Mn: 1.4-2.2, Mo: 0.05-0.5, Al: 0.015-0.1, P: up to 0.02, S: up to 0.01, B: up to 0.006, and at least one element from the group Nb, V, Ti in accordance with the following condition: 0.02<=Nb+V+Ti<=0.20, the remainder being iron including unavoidable steel-accompanying elements resulting from the melting process, casting the steel melt into a preliminary material, in particular a slab or a block or a thin slab, hot rolling the preliminary material into a hot-rolled strip having a final rolling temperature in the range of 800 to 950? C., cooling the hot-rolled strip to a winding temperature less than 650? C., winding the hot-rolled strip at a winding temperature less than 650? C., cooling the wound hot-rolled strip to room temperature in still air, wherein the microstructure of the wound hot-rolled strip then has a bainite fraction greater than 50% after the hot rolling, heating the hot-rolled strip to a temperature greater than 650? C. and less than Ac3, in particular less than Ac1+50? C., cooling the hot-rolled strip to zinc bath temperature, hot-dip coating the heated hot-rolled strip in a zinc alloy molten bath containing (in weight percent): Al: 1.0-2.0, Mg: 1.0-2.0, the remainder being zinc and unavoidable impurities. The invention further relates to the hot-rolled strip produced in accordance with the method above and to shaped, dynamically highly loadable components, in particular motor vehicle parts, that are produced from said hot-rolled strip and that are resistant to corrosive and abrasive influences.

This steel sheet for containers includes a steel sheet, a Sn coated layer that is formed on at least one surface of the steel sheet, and a chemical treatment layer that is formed on the Sn coated layer. The Sn coated layer contains 300 mg/m.sup.2 to 5,600 mg/m.sup.2 of Sn in terms of an amount of metal Sn, and the chemical treatment layer contains 5 mg/m.sup.2 to 30 mg/m.sup.2 of a Zr compound in terms of an amount of metal Zr, an average roughness Ra of an outermost surface of the chemical treatment layer obtained with a scanning probe microscope is 10 nm to 100 nm. A variation amount in a yellowness index measured at one measurement point on the outermost surface of the chemical treatment layer is defined as YI represented by Equation (1), an average of absolute values of the YI obtained at a plurality of the measurement points included in a unit area of the outermost surface is 5.0 or less.

YI=YIYI.sub.0(1) where YI: the yellowness index measured after the steel sheet for containers is subjected to a retort treatment at a temperature of 130 C. for 5 hours, YI.sub.0: the yellowness index measured before the retort treatment

A cold-rolled steel sheet for vitreous enameling has a predetermined chemical composition, in which a number density of FeMnNb-based composite oxides having a diameter of 0.2 m to 10 m is 210.sup.2 particle/mm.sup.2 to 110.sup.4 particle/mm.sup.2; a fatigue limit ratio is higher than 0.42 after performing a heat treatment with an applied tensile strain of 10% at a heating temperature of 830 C. for a holding time of 5 minutes; voids are formed between the metallographic structure and the FeMnNb-based composite oxides, and an equivalent circle diameter of the voids is 0.1 m to 0.6 m; and when each of the voids is approximated as a triangle and a long side of the triangle is set as a base, a value obtained by dividing a length of the base by a height of the triangle is 1.0 to 15.

Provided is an ultra-high strength hot-rolled steel sheet which is mainly used for components requiring high strength and excellent bending workability. The ultra-high strength hot-rolled steel sheet comprises: 0.1 to 0.25 wt % of C; 0.01 to 0.2 wt % of Si; 0.5 to 2.0 wt % of Mn; 0.005 to 0.02 wt % of P; 0.001 to 0.01 wt % of S; and a balance of Fe and other inevitable impurities. The ultra-high strength hot-rolled steel sheet further comprises 0.001 to 0.35 wt % of at least one element selected from the group consisting of Ti, Nb, Mo, Cr, and B, and the following Relational Expression 1 is satisfied, relational Expression 69.2-311.5[C]-0.1[Si]-4.0[Mn]-5.3[Cr]-2.6[Ni]-6.6[Ti]-660.6 [B]-39[P]0, where [C], [Si], [Mn], [Cr], [Ni], [Ti], [B], and [P] refer to wt % of the content of each element.

This relates to a process for manufacturing a recovery annealed coated steel substrate for packaging applications and a packaging steel product produced thereby.

A method of manufacturing a high strength steel sheet includes subjecting a steel having a chemical composition including C: 0.08% to 0.20%, Si: 0.3% or less, Mn: 0.1% to 3.0%, P: 0.10% or less, S: 0.030% or less, Al: 0.10% or less, N: 0.010% or less, V: 0.20% to 0.80%, and the remainder composed of Fe and incidental impurities on a percent by mass basis to a hot rolling process composed of heating, rough rolling, finish rolling, cooling, and coiling into the shape of a coil at a predetermined coiling temperature, wherein the heating is performed at a temperature of 1,100 C. or higher for 10 min or more, the rough rolling is performed at a finish rough rolling temperature of 1,000 C. or higher, the finish rolling is performed at a finishing temperature of 850 C. or higher, in which a reduction ratio in a temperature range of 1,000 C. or lower is 96% or less, a reduction ratio in a temperature range of 950 C. or lower is 80% or less, the cooling after completion of the finish rolling is performed at an average cooling rate of (30[V]) C./s or more in relation to the V content [V] (percent by mass) in a temperature range from the finishing temperature to 750 C. and at an average cooling rate of (10[V]) C./s or more in relation to the V content [V] (percent by mass) in a temperature range from 750 C. to the coiling temperature, and the coiling temperature is 500 C. or higher and (70050[V]) C. or lower in relation to the V content [V] (percent by mass).

A high-manganese hot-rolled galvanized steel sheet having no surface defects and improved galvanizing and alloying characteristics is manufactured by using a high-manganese hot-rolled steel sheet. Provided are the high-manganese hot-rolled galvanized steel sheet and a method of manufacturing the high-manganese hot-rolled galvanized steel sheet. The high-manganese hot-rolled galvanized steel sheet includes: a hot-rolled steel sheet including 5 wt % to 35 wt % manganese; and a zinc coating layer formed on the hot-rolled steel sheet, wherein an internal oxide layer is formed in an internal region of the hot-rolled steel sheet facing the zinc coating layer.

A base steel sheet has a hot-dip galvanized layer formed on a surface thereof, in which, in a steel sheet structure in a range of thickness to thickness centered around thickness of a sheet thickness from a surface, a volume fraction of a retained austenite phase is 5% or less, and a total volume fraction of phases of bainite, bainitic ferrite, fresh martensite, and tempered martensite is 40% or more, an average effective crystal grain diameter is 5.0 m or less, a maximum effective crystal grain diameter is 20 m or less, and a decarburized layer with a thickness of 0.01 m to 10.0 m is formed on a surface layer portion, in which a density of oxides dispersed in the decarburized layer is 1.010.sup.12 to 1.010.sup.16 oxides/m.sup.2, and an average grain diameter of the oxides is 500 nm or less.