Disclosed are a non-oriented electrical steel sheet with excellent magnetic properties and a manufacturing method thereof, wherein the mass percentage of the chemical components thereof are: C: 0-0.005%; Si: 2.1-3.2%, Mn: 0.2-1.0%, P: 0-0.2%, Al: 0.2-1.6%, N: 0-0.005%, Ti: 0-0.005%, Cu: 0-0.2%, and the balance of Fe and inevitable impurities; and at the same time, (the S content for forming MnS+the S content for forming CuxS)/the S content in the steel is required to be less than or equal to 0.2. The process for manufacturing the non-oriented electrical steel sheet of the present invention is simple and convenient, the chemical components of the steel are easy to control, the manufacturing process is stable, and the technical requirements are easy to realize.

Embodiments include a method of making steel with low carbon content which includes preparing a heat of molten steel composition in a steelmaking furnace to a tapping temperature ranging from 2912 to 3060 degrees F. and tapping into a ladle the molten steel composition having an oxygen level is about 700 to 1000 ppm. The molten steel composition is then transported to a ladle metallurgy furnace, where the molten steel composition is further heated and one or more elements are added to the molten steel composition. The molten steel composition is then transported from the ladle metallurgy furnace to a vacuum tank degasser. The molten steel composition is then decarburized and one or more elements are added to the molten steel composition at the vacuum tank degasser for deoxidization and desulphurization. The molten steel composition is then transported to a ladle metallurgy furnace to further adjust chemistry and temperature.

Embodiments include a method of making steel with low carbon content which includes preparing a heat of molten steel composition in a steelmaking furnace to a tapping temperature ranging from 2912 to 3060 degrees F. and tapping into a ladle the molten steel composition having an oxygen level is about 700 to 1000 ppm. The molten steel composition is then transported to a ladle metallurgy furnace, where the molten steel composition is further heated and one or more elements are added to the molten steel composition. The molten steel composition is then transported from the ladle metallurgy furnace to a vacuum tank degasser. The molten steel composition is then decarburized and one or more elements are added to the molten steel composition at the vacuum tank degasser for deoxidization and desulphurization. The molten steel composition is then transported to a ladle metallurgy furnace to further adjust chemistry and temperature.

A spring steel having a superior fatigue life, and a manufacturing method for the same. The chemical components thereof are as follows in weight percentage: C: 0.52-0.62%, Si: 1.20-1.45%, Mn: 0.25-0.75%, Cr: 0.30-0.80%, V: 0.01-0.15%, Nb: 0.001-0.05%, N: 0.001-0.009%, O: 0.0005-0.0040%, P: ≤0.015%, S: ≤0.015%, and Al: ≤0.0045%, with the remainder being Fe and incidental impurities, wherein the following condition is also met 0.02≤(2Nb+V)/(20N+C)≤0.40. The spring steel of the present invention has a microstructure of tempered troostite+tempered sorbite, a prior austenite grain size less than 80 um, a size of alloy nitride and carbide precipitates being 5-60 nm, and a maximum width of single-grain inclusions being less than 30 pm. The spring steel has a handling strength greater than 2020 MPa, superior ductility and toughness (the reduction of area≥40%), and a fatigue life≥800,000 times, thereby meeting application requirements of high-stress springs in industries, such as automobiles, machinery, and the like.

A method for producing metal powders by gas atomization is provided, including providing a metal charge; melting the metal charge inside an electric-arc furnace, controlling its composition until a molten metal bath having a desired composition is obtained; tapping the bath from the furnace, collecting it inside a ladle; refining the bath under controlled atmosphere, vacuum, or overpressure condition; atomizing the refined bath by feeding it into a gas atomizer, inside which a molten metal bath flow is produced, and impinging the molten metal bath flow with an atomization inert gas stream for the atomization of the molten metal bath into metal powders; and extracting the obtained metal powders from the gas atomizer.

A method for producing metal powders by gas atomization is provided, including providing a metal charge; melting the metal charge inside an electric-arc furnace, controlling its composition until a molten metal bath having a desired composition is obtained; tapping the bath from the furnace, collecting it inside a ladle; refining the bath under controlled atmosphere, vacuum, or overpressure condition; atomizing the refined bath by feeding it into a gas atomizer, inside which a molten metal bath flow is produced, and impinging the molten metal bath flow with an atomization inert gas stream for the atomization of the molten metal bath into metal powders; and extracting the obtained metal powders from the gas atomizer.

Provided are a high-strength steel sheet having a specified chemical composition, in which a Mn-segregation degree in a region within 100 m from a surface thereof in a thickness direction is 1.5 or less, in a plane parallel to the surface of the steel sheet in a region within 100 m from the surface of the steel sheet in the thickness direction, the number of oxide-based inclusion grains having a grain long diameter of 5 m or more is 1000 or less/100 mm.sup.2, a proportion of the number of oxide-based inclusion grains having a chemical composition containing alumina of 50 mass % or more, silica of 20 mass % or less, and calcia of 40 mass % or less to the total number of oxide-based inclusions having a grain long diameter of 5 m or more is 80% or more, a specified metallographic structure, and a TS of 980 MPa or more, a high-strength galvanized steel sheet, and a manufacturing method thereof.

Provided are a high-strength steel sheet having a specified chemical composition, in which a Mn-segregation degree in a region within 100 m from a surface thereof in a thickness direction is 1.5 or less, in a plane parallel to the surface of the steel sheet in a region within 100 m from the surface of the steel sheet in the thickness direction, the number of oxide-based inclusion grains having a grain long diameter of 5 m or more is 1000 or less/100 mm.sup.2, a proportion of the number of oxide-based inclusion grains having a chemical composition containing alumina of 50 mass % or more, silica of 20 mass % or less, and calcia of 40 mass % or less to the total number of oxide-based inclusions having a grain long diameter of 5 m or more is 80% or more, a specified metallographic structure, and a TS of 980 MPa or more, a high-strength galvanized steel sheet, and a manufacturing method thereof.

Ti, N, Al, Mg, and Ca concentrations are controlled in order to prevent aggregation of TiN inclusions. Furthermore, not only is a FeCrNi alloy having superior surface property provided, but also a method is proposed in which the FeCrNi alloy is produced at low cost using commonly used equipment. The FeCrNi alloy includes C0.05%, Si: 0.1 to 0.8%, Mn: 0.2 to 0.8%, P0.03%, S0.001%, Ni:16 to 35%, Cr: 18 to 25%, Al: 0.2 to 0.4%, Ti: 0.25 to 0.4%, N0.016%, Mg: 0.0015 to 0.008%, Ca0.005%, O: 0.0002 to 0.005%, freely selected Mo: 0.5 to 2.5% in mass % and Fe and inevitable impurities as the remainder, wherein Ti and N satisfy % N% Ti0.0045 and the number of TiN inclusions not smaller than 5 m is 20 to 200 pieces/cm.sup.2 at a freely selected cross section.

Ti, N, Al, Mg, and Ca concentrations are controlled in order to prevent aggregation of TiN inclusions. Furthermore, not only is a FeCrNi alloy having superior surface property provided, but also a method is proposed in which the FeCrNi alloy is produced at low cost using commonly used equipment. The FeCrNi alloy includes C0.05%, Si: 0.1 to 0.8%, Mn: 0.2 to 0.8%, P0.03%, S0.001%, Ni:16 to 35%, Cr: 18 to 25%, Al: 0.2 to 0.4%, Ti: 0.25 to 0.4%, N0.016%, Mg: 0.0015 to 0.008%, Ca0.005%, O: 0.0002 to 0.005%, freely selected Mo: 0.5 to 2.5% in mass % and Fe and inevitable impurities as the remainder, wherein Ti and N satisfy % N% Ti0.0045 and the number of TiN inclusions not smaller than 5 m is 20 to 200 pieces/cm.sup.2 at a freely selected cross section.