An oriented electrical steel sheet according to an embodiment of the present invention includes, in a unit of wt %, Si at 1.0 wt % to 5.0 wt %, C at 0.005 wt % or less (excluding 0 wt %), Mn at 0.001 wt % to 0.1 wt %, Cu at 0.001 wt % to 0.1 wt %, S at 0.001 wt % to 0.020 wt %, Se at 0.001 wt % to 0.050 wt %, Al at 0.0005 wt % to 0.010 wt %, N at 0.0005 wt % to 0.005 wt %, and the remainder of Fe and inevitable impurities.

The oriented electrical steel sheet according to the embodiment of the present invention satisfies Equation 1.

16≤(10×[Mn]+[Cu])/([S]+[Se])+(0.02−[Al])/[N]≤20  [Equation 1]

(In Equation 1, [Mn], [Cu], [S], [Se], [Al], and [N] represent contents (wt %) of Mn, Cu, S, Se, Al, and N, respectively.)

A hot-rolled strip steel product having a chemical composition consisting of, in terms of weight percentages (wt. %): 0.025%-0.070% C, 0%-1.10% Si, 0.50%-2.0% Mn, <0.020% P, <0.050% S, <0.010% N, 0%-0.60% Cr, 0%-0.20% Ni, 0%-0.25% Cu, 0%-0.20% Mo, 0%-0.15% Al, 0%-0.050% Nb, 0.020%-0.20-% V, 0.020%-0.15% Ti, 0%-0.0010% B, remainder Fe and inevitable impurities, wherein the strip steel product has a microstructure comprising of, in terms of volume percentages (vol. %), ferrite ≥90%, wherein the ferrite structure comprises 10%-50% quasi-polygonal ferrite and a reminder of ferrite structure is polygonal ferrite and/or bainite: and wherein the steel strip product has an average ferrite grain size of <10 μm, an average hole expansion ratio of ≥50%, a yield strength (Rp0.2%) longitudinal to rolling direction of ≥660 MPa and a tensile strength of ≥760 MPa.

A steel for mining chain and a manufacturing method thereof, wherein the steel has compositions by weight percentage: C: 0.20-0.28%, Si: 0.01-0.40%, Mn: 0.50-1.50%, P≤0.015%, S≤0.005%, Cr: 0.30-2.00%, Ni: 0.50-2.00%, Mo: 0.10-0.80%, Cu: 0.01-0.30%, Al: 0.01-0.05%, Nb: 0.001-0.10%, V: 0.001-0.10%, H≤0.00018%, N≤0.0150%, O≤0.0020%, and the balance is Fe and inevitable impurities. The manufacturing method comprises steps of smelting, refining and vacuum treatment, casting, heating, forging or rolling, and quenching and tempering heat treatment processes. The steel in the present invention has high strength and good impact toughness, good elongation and reduction of area. The steel can also resist stress corrosion cracking and have good weather resistance, wear resistance and fatigue resistance, which can be used in scenarios where the steel having high strength and toughness is required, such as construction machinery and marine engineering.

A hot rolled and annealed steel sheet having a composition including, by weight percent: C: 0.1-0.25%, Mn: 3.00-5.00%, Si: 0.80-1.60%, B: 0.0003-0.004%, S≤0.010%, P≤0.020%, N≤0.008% the remainder of the composition being iron and unavoidable impurities resulting from the smelting, and having a microstructure consisting of, in surface fraction: more than 20% of recrystallized ferrite, the balance being non-recrystallized ferrite, more than 15% of said recrystallized ferrite having grain size larger than 5 μm and a density of carbides at grain boundary of recrystallized ferrite less than 5 carbides per 10 μm of grain boundary length

A cold rolled and heat-treated steel sheet having a composition including, by weight percent C: 0.12-0.25% Mn: 3.0-8.0%, Si: 0.70-1.50%, Al: 0.3-1.2%, B: 0.0002-0.004%, S≤0.010%, P≤0.020%, N≤0.008%, the remainder of the composition being iron and unavoidable impurities resulting from the smelting, and having a microstructure consisting of, in surface fraction: between 5% and 45% of ferrite, between 25% and 85% of partitioned martensite, the partitioned martensite having a carbides density strictly less than 2×10.sup.6/mm.sup.2, between 10% and 30% of retained austenite, less than 8% of fresh martensite, a part of the fresh martensite being combined with retained austenite in the shape of martensite-austenite islands in total surface fraction less than 10%.

The invention relates to a process for producing an at least partly quenched and tempered sheet steel component, where the process comprises the following steps: providing a sheet steel, at least partly austenitizing the sheet steel at a temperature of at least Ac1, at least partly hardening the at least partly austenitized sheet steel to give an at least partly hardened sheet steel component, where the at least partly austenitized sheet steel is cooled to a temperature below Ms, at least partly annealing the at least partly hardened sheet steel component at a temperature of less than Ac1 for producing an at least partly quenched and tempered sheet steel component. A further subject of the invention is an at least partly quenched and tempered sheet steel component.

A high-strength cold-rolled steel sheet comprises: a chemical composition that contains C, Si, Mn, P, S, N, Al, Ti, Nb, and B with a balance consisting of Fe and inevitable impurities, and satisfies [mol % N]/[mol % Ti]<1; and a steel microstructure in which: an area fraction of ferrite is 30% or more and 60% or less; a total area fraction of tempered martensite and bainite is 35% or more and 65% or less; an area fraction of quenched martensite is 15% or less; an area fraction of retained austenite is 1% or more and 10% or less; an area fraction of low-Mn ferrite having a Mn concentration of 0.8×[% Mn] or less is 5% or more and 40% or less; a result of subtracting the area fraction of the low-Mn ferrite from the area fraction of the ferrite is 10% or more; an area fraction of a residual microstructure is less than 3%; and an average grain size of the low-Mn ferrite is 10 μm or less.

Disclosed in the present invention is a manufacturing method for a carbon steel and austenitic stainless-steel rolling clad plate, comprising the steps of: (1) obtaining a blank material of a carbon steel layer and a blank material of a stainless-steel layer; (2) assembling blank materials; (3) cladding and rolling; (4) cold rolling; (5) first annealing; and (6) second annealing. The carbon steel and austenitic stainless-steel rolling clad plate has two unique annealing processes, so that the clad plate has the performance advantages of the austenitic stainless-steel and the carbon steel. In addition, further disclosed in the present invention is a carbon steel and austenitic stainless-steel rolling clad plate manufactured by this method.

The present invention provides a rare-earth sintered magnet that is characterized in that: R (R indicates one or more elements selected from rare-earth elements, wherein Nd is essential), T (T indicates one or more elements selected from iron-group elements, wherein Fe is essential), X (X indicates one or two elements selected from B and C, wherein B is essential), M.sup.1 (M.sup.1 indicates one or more elements selected from Al, Si, Cr, Mn, Cu, Zn, Ga, Ge, Mo, Sn, W, Pb, and Bi), 0.1 mass % or less of O, 0.05 mass % or less of N, and 0.07 mass % or less of C are contained; the average crystal grain size is 4.0 μm or less; and relational expression (1) 0.26×D+97≤Or≤0.26×D+99 is satisfied assuming that the degree of orientation is Or [%] and that the average crystal grain size is D [μm]. With this rare-earth sintered magnet, it is possible to achieve superior magnetic characteristics in which both high Br and high H.sub.cJ are achieved.

The present disclosure relates to a zinc plated steel sheet having excellent fatigue strength of electrical resistance spot welds and a method for manufacturing the same. According to an aspect of the present disclosure, a zinc plated steel sheet includes a base steel sheet and a zinc-based plating layer formed on a surface of the base steel sheet, wherein a concentration profile of one or two of oxygen, and silicon and manganese measured in a depth direction from the surface of the base steel sheet has a maximum point in the depth direction from the surface, and an absolute value of a difference between a depth at which the maximum point of the concentration profile of oxygen is formed and a depth at which the maximum point of the concentration profile of one of silicon and manganese is formed is 0.5 μm or less.