Provided are an ultra-clean rare earth steel and an occluded foreign substance modification control method, the steel includes 10-200 ppm of rare earth elements, 50% or more occluded foreign substances in the steel are dispersed into RE-oxygen-sulfide with the average equivalent diameter D.sub.mean ranging from 1-5 μm in a spherical shape or a substantially spherical shape or a granular shape; according to the method, at least 80%, preferably at least 90%, of Al2O3 occluded foreign substances in the steel are modified into RE-oxygen-sulfide, compared with steel with the same components without rare earth, the total amount of the occluded foreign substances in the steel is reduced by 18% or higher, the cracking probability caused by occluded foreign substances such as Al2O3 in traditional pure steel is reduced, the mechanical performance such as the fatigue life of the steel is remarkably improved.

Provided are an ultra-clean rare earth steel and an occluded foreign substance modification control method, the steel includes 10-200 ppm of rare earth elements, 50% or more occluded foreign substances in the steel are dispersed into RE-oxygen-sulfide with the average equivalent diameter D.sub.mean ranging from 1-5 μm in a spherical shape or a substantially spherical shape or a granular shape; according to the method, at least 80%, preferably at least 90%, of Al2O3 occluded foreign substances in the steel are modified into RE-oxygen-sulfide, compared with steel with the same components without rare earth, the total amount of the occluded foreign substances in the steel is reduced by 18% or higher, the cracking probability caused by occluded foreign substances such as Al2O3 in traditional pure steel is reduced, the mechanical performance such as the fatigue life of the steel is remarkably improved.

Provided is a non-oriented electrical steel sheet having such a low Al concentration so that it is excellent in terms of the recycling efficiency of scrap iron and having a high magnetic flux density and low iron loss.

The non-oriented electrical steel sheet according to the present invention has a chemical composition containing C; 0.0050 mass % or less, Si; 1.5 mass % to 5.0 mass %, Mn; 0.2 mass % to 3.0 mass %, sol.Al; 0.0030 mass % or less, P; 0.2 mass % or less, S; 0.0050 mass % or less, N; 0.0040 mass % or less, T.Ca; 0.0010 mass % to 0.0080 mass %, T.O; 0.0100 mass % or less, REM; 0.0001 mass % to 0.0050 mass %, and a balance of Fe and inevitable impurities, in which a value of a mass-related fractional expression ((T.Ca+REM)/(T.O+S)), which is a relational expression for the masses of the four constituents described above, that is, T.Ca, REM, T.O, and S, is 0.4 or more.

Ti, N, Al, Mg, and Ca concentrations are controlled in order to prevent aggregation of TiN inclusions. Furthermore, not only is a Fe—Cr—Ni alloy having superior surface property provided, but also a method is proposed in which the Fe—Cr—Ni alloy is produced at low cost using commonly used equipment. The Fe—Cr—Ni alloy includes C≤0.05%, Si: 0.1 to 0.8%, Mn: 0.2 to 0.8%, P≤0.03%, S≤0.001%, Ni:16 to 35%, Cr: 18 to 25%, Al: 0.2 to 0.4%, Ti: 0.25 to 0.4%, N≤0.016%, Mg: 0.0015 to 0.008%, Ca≤0.005%, 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×% Ti≤0.0045 and the number of TiN inclusions not smaller than 5 μm is 20 to 200 pieces/cm.sup.2 at a freely selected cross section.

A non-heat treated steel bar according to the present disclosure has a chemical composition consisting of, in mass percent, C: 0.39 to 0.55%, Si: 0.10 to 1.00%, Mn: 0.50 to 1.50%, P: 0.010 to 0.100%, S: 0.040 to 0.130%, Cr: 0.05 to 0.50%, V: 0.05 to 0.40%, Ti: 0.10% to 0.25%, Al: 0.003 to 0.100%, and N: 0.020% or less, with the balance being Fe and impurities, and satisfying Formula (1). A number density of Al.sub.2O.sub.3-based inclusions in each of which Al.sub.2O.sub.3 is contained at 70.0% or more in mass % and √AREA is not less than 3 μm is 0.05 to 1.00/mm.sup.2.
0.60≤C+0.2Mn+0.25Cr+0.75V+0.81Mo≤1.00  (1)

A non-heat treated steel bar according to the present disclosure has a chemical composition consisting of, in mass percent, C: 0.39 to 0.55%, Si: 0.10 to 1.00%, Mn: 0.50 to 1.50%, P: 0.010 to 0.100%, S: 0.040 to 0.130%, Cr: 0.05 to 0.50%, V: 0.05 to 0.40%, Ti: 0.10% to 0.25%, Al: 0.003 to 0.100%, and N: 0.020% or less, with the balance being Fe and impurities, and satisfying Formula (1). A number density of Al.sub.2O.sub.3-based inclusions in each of which Al.sub.2O.sub.3 is contained at 70.0% or more in mass % and √AREA is not less than 3 μm is 0.05 to 1.00/mm.sup.2.
0.60≤C+0.2Mn+0.25Cr+0.75V+0.81Mo≤1.00  (1)

A cored wire for refining molten metal includes a reactive core material that is in the form of a solid rod. A non-reactive particulate material radially surrounds the solid core material, and an exterior metal jacket radially surrounds the particulate material. The particulate material may include wood or other material that when introduced into the molten metal, undergoes thermal decomposition to release carbon dioxide, hydrocarbons, or combinations thereof as a shroud around the core material.

A cored wire for refining molten metal includes a reactive core material that is in the form of a solid rod. A non-reactive particulate material radially surrounds the solid core material, and an exterior metal jacket radially surrounds the particulate material. The particulate material may include wood or other material that when introduced into the molten metal, undergoes thermal decomposition to release carbon dioxide, hydrocarbons, or combinations thereof as a shroud around the core material.

Provided is an FeNiCr alloy that has excellent surface characteristics and enables formation of a blackened coating having excellent blackening characteristics and peeling resistance. The FeNiCr alloy has a chemical composition containing, by mass %, C, Si, Mn, P, S, Cr, Ni, Mo, Co, Cu, N, Ti, Al, O, and H, the balance being Fe and inevitable impurities, and satisfying formulae (1) to (4): (1) T1=11[% N]+0.1; (2) T2=39[% N]1.0; (3) A1=7.5[% N]+0.1; (4) A2=42.5[% N]+1.0, where [% M] represents content (mass %) of element M in the alloy, and T1, T2, A1, and A2 satisfy relationships T1<[% Ti]<T2 and A1<[% A1]<A2.

A cored wire for refining molten metal includes a reactive core material that is in the form of a solid rod. A non-reactive particulate material radially surrounds the solid core material, and an exterior metal jacket radially surrounds the particulate material. The particulate material may include wood or other material that when introduced into the molten metal, undergoes thermal decomposition to release carbon dioxide, hydrocarbons, or combinations thereof as a shroud around the core material.