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.

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.

The purpose of the present invention is to provide a method for eluting Ca from steelmaking slag such that a large amount of Ca can be eluted from the steelmaking slag into an aqueous solution containing carbon dioxide. The present invention executes, in this order: a step for removing an iron-containing compound from steelmaking slag by performing magnetic separation on the steelmaking slag; and a step for bringing the steelmaking slag subjected to magnetic separation into contact with an aqueous solution containing carbon dioxide. In addition, the aqueous solution containing carbon dioxide and the steelmaking slag are brought into contact with each other while the steelmaking slag is being pulverized or the surface of the steelmaking slag is being ground.

The purpose of the present invention is to provide a method for eluting Ca from steelmaking slag such that a large amount of Ca can be eluted from the steelmaking slag into an aqueous solution containing carbon dioxide. The present invention executes, in this order: a step for removing an iron-containing compound from steelmaking slag by performing magnetic separation on the steelmaking slag; and a step for bringing the steelmaking slag subjected to magnetic separation into contact with an aqueous solution containing carbon dioxide. In addition, the aqueous solution containing carbon dioxide and the steelmaking slag are brought into contact with each other while the steelmaking slag is being pulverized or the surface of the steelmaking slag is being ground.

A molten steel refining method includes throwing a powder to molten steel while heating the powder with a flame formed by combustion of a hydrocarbon gas at the leading end of a top blowing lance. The lance height of the top blowing lance (the distance between the static bath surface of the molten steel and the leading end of the lance) is controlled to 1.0 to 7.0 m, and the dynamic pressure P of a jet flow ejected from the top blowing lance calculated from equation (1) below is controlled to 20.0 kPa or more and 100.0 kPa or less. P=.sub.g U.sup.2/2 . . . (1) wherein P is the dynamic pressure (kPa) of the jet flow at an exit of the top blowing lance, .sub.g the density (kg/Nm.sup.3) of the jet flow, and U the velocity (m/sec) of the jet flow at the exit of the top blowing lance.

A molten steel refining method includes throwing a powder to molten steel while heating the powder with a flame formed by combustion of a hydrocarbon gas at the leading end of a top blowing lance. The lance height of the top blowing lance (the distance between the static bath surface of the molten steel and the leading end of the lance) is controlled to 1.0 to 7.0 m, and the dynamic pressure P of a jet flow ejected from the top blowing lance calculated from equation (1) below is controlled to 20.0 kPa or more and 100.0 kPa or less. P=.sub.g U.sup.2/2 . . . (1) wherein P is the dynamic pressure (kPa) of the jet flow at an exit of the top blowing lance, .sub.g the density (kg/Nm.sup.3) of the jet flow, and U the velocity (m/sec) of the jet flow at the exit of the top blowing lance.

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 m is 0.05 to 1.00/mm.sup.2.

0.60C+0.2Mn+0.25Cr+0.75V+0.81Mo1.00 (1)

A hot rolled steel sheet having a chemical composition consisting of, in mass %, C: 0.020-0.070%, Si: 0.05-1.70%, Mn: 0.60-2.50%, Al: 0.005-0.020%, N: >0.0030-0.0060%, P0.050%, S0.005%, Ti: 0.015-0.170%, Nb: 0-0.100%, V: 0-0.300%, Cu: 0-2.00%, Ni: 0-2.00%, Cr: 0-2.00%, Mo: 0-1.00%, B: 0-0.0100%, Ca: 0-0.0100%, Mg: 0-0.0100%, REM: 0-0.1000%, Zr: 0-1.000%, Co: 0-1.000%, Zn: 0-1.000%, W: 0-1.000%, Sn: 0-0.050%, the balance: Fe and impurities, wherein Ca+Mg+REM0.0005, a metal microstructure includes, in area %, ferrite: 5-70%, bainite: 30-95%, retained 2%, martensite 2%, pearlite 1%, ferrite+bainite95%, a number density of the precipitates in ferrite grains is 1.010.sup.16-50.010.sup.16/cm.sup.3, an average circle-equivalent diameter of the TiN precipitates in the steel sheet is 1.0-10.0 m, an average of minimum distances between adjacent TiN precipitates is 10.0 m or more, and a standard deviation of nano hardness is 1.00 GPa or less.

Low-oxygen clean steel is provided containing C, Si, Mn, P, and S as chemical components, and further containing, by mass %, 0.005% to 0.20% of Al, greater than 0% to 0.0005% of Ca, 0.00005% to 0.0004% of REM, and greater than 0% to 0.003% of T.O, wherein the REM content, the Ca content, and the T.O content satisfy 0.15REM/Ca4.00 and Ca/T.O0.50, nonmetallic inclusions which have a maximum predicted diameter of 1 m to 30 m measured using an extreme value statistical method under the condition in which a prediction area is 30,000 mm.sup.2, and contain Al.sub.2O.sub.3 and REM oxide are dispersed in the steel, an average proportion of the Al.sub.2O.sub.3 in the nonmetallic inclusions is greater than 50%, the REM is one or two or more of rare-earth elements La, Ce, Pr, and Nd, and the steel is Al-deoxidized steel or AlSi-deoxidized steel.

Low-oxygen clean steel is provided containing C, Si, Mn, P, and S as chemical components, and further containing, by mass %, 0.005% to 0.20% of Al, greater than 0% to 0.0005% of Ca, 0.00005% to 0.0004% of REM, and greater than 0% to 0.003% of T.O, wherein the REM content, the Ca content, and the T.O content satisfy 0.15REM/Ca4.00 and Ca/T.O0.50, nonmetallic inclusions which have a maximum predicted diameter of 1 m to 30 m measured using an extreme value statistical method under the condition in which a prediction area is 30,000 mm.sup.2, and contain Al.sub.2O.sub.3 and REM oxide are dispersed in the steel, an average proportion of the Al.sub.2O.sub.3 in the nonmetallic inclusions is greater than 50%, the REM is one or two or more of rare-earth elements La, Ce, Pr, and Nd, and the steel is Al-deoxidized steel or AlSi-deoxidized steel.