A method for treating molten iron includes applying a metal treatment agent to molten iron; and stirring the molten iron using a rotary device comprising a rotor head. The rotary device can be resistant to corrosion and thermal shock, and thereby permit efficient application of metal treatment agents.

A rotary device and methods for treating molten metal, a tubular sleeve for said rotary device and the use of said rotary device in the treatment of molten metal. The rotary device comprises: a tubular sleeve comprising a rotor head at one end, the rotor head comprising a gas outlet for dispersing gas into molten metal; and a hollow shaft extending inside the tubular sleeve such that at least a portion of the hollow shaft is enclosed by the tubular sleeve, wherein the hollow shaft is fluidly connected to the gas outlet of the rotor head, the tubular sleeve is formed from a refractory material that is resistant to corrosion and thermal shock, and the hollow shaft is formed from a material comprising graphite. A first method comprises: applying a layer of synthetic slag material onto an exposed surface of the molten metal; and stirring the molten metal using a rotary device comprising a rotor head, such that the molten metal flows past the layer of synthetic slag material. A second method comprises: applying a metal treatment agent to molten metal; stirring the molten metal using a rotary device comprising a rotor head; and discharging gas into the molten metal through the rotor head.

A process for manufacturing an iron-based alloy comprising forming targeted fine oxide and/or carbide dispersoids in a melt, and sequentially precipitating transition-metal nitrides on the dispersoids for heterogeneous nucleation of equiaxed grains. An iron-based cast alloy having a highly equiaxed fine grain structure.

Provided is a molten steel treatment device and a molten steel treatment method using same. The molten steel treatment method may include: preparing slag on molten steel; contacting a first electrode to at least a portion of the slag and a second electrode to at least a portion of the molten steel; and polarizing the slag by applying a voltage to the first electrode and the second electrode, to easily remove inclusions and impurity elements in the molten steel by controlling basicity and oxidation degree of the slag without using separate additives.

A steel for induction hardening according to the present invention includes a chemical composition consisting of, in mass percent: C: 0.53 to less than 0.58%, Si: 0.70 to 1.40%, Mn: 0.20 to 1.40%, P: less than 0.020%, S: 0.025% or less, Al: more than 0.06% to 0.15%, N: 0.0020 to 0.0080%, O: 0.0015% or less, B: 0.0003 to 0.0040%, Ti: 0.010 to 0.050%, and Ca: 0.0005 to 0.005%, with the balance being Fe and impurities, and satisfies Formulae (1) to (3). The steel microstructure is made up of ferrite and pearlite. A ratio of a number of composite inclusions is 20% or more.

C+Si/7+Mn/5+Cr/9+Mo/2.50.98(1)

C+Si/10+Mn/20+Cr/250.70(2)

Cr/Si0.20(3)

A steel for induction hardening according to the present invention includes a chemical composition consisting of, in mass percent: C: 0.58 to 0.68%, Si: 0.70 to 1.40%, Mn: 0.20 to 1.40%, Al: 0.005 to 0.060%, N: 0.0020 to 0.0080%, and Ca: 0.0005 to 0.005%, with the balance being Fe and impurities, and satisfies Formulae (1) to (3). The steel microstructure is made up of ferrite and by area fraction, 85% or more of pearlite. In the steel, a ratio of a number of composite inclusions to a total number of Al.sub.2O.sub.3 inclusions and the composite inclusions that contain 2.0% or more of SiO.sub.2 and 2.0% or more of CaO is 20% or more.

C+Si/7+Mn/5+Cr/9+Mo/2.51.05(1)

C+Si/10+Mn/20+Cr/250.70(2)

Cr/Si0.20(3)

A steel for induction hardening according to the present invention includes a chemical composition consisting of, in mass percent: C: 0.58 to 0.68%, Si: 0.70 to 1.40%, Mn: 0.20 to 1.40%, P: less than 0.020%, S: 0.025% or less, Al: more than 0.06% to 0.15%, N: 0.0020 to 0.0080%, O: 0.0015% or less, and Ca: 0.0005 to 0.005%, with the balance being Fe and impurities, and satisfies Formulae (1) to (3). The steel microstructure is made up of ferrite and pearlite. In the steel, a ratio of a number of composite inclusions to a total number of Al.sub.2O.sub.3 inclusions and the composite inclusions is 20% or more.

C+Si/7+Mn/5+Cr/9+Mo/2.51.05(1)

C+Si/10+Mn/20+Cr/250.70(2)

Cr/Si0.20(3)

A gas pressure tank structure including: a tank wall, a compression oil cylinder, a locking ring, a spring cylinder, a locating pin mounting hole, a dowel pinhole, a refractory brick, a guide mechanism, a sealing structure, an arc joint, an arc shaped tank bottom, a steel ladle stand, a tank cover, and a reinforcing board.

A gas pressure tank structure including: a tank wall, a compression oil cylinder, a locking ring, a spring cylinder, a locating pin mounting hole, a dowel pinhole, a refractory brick, a guide mechanism, a sealing structure, an arc joint, an arc shaped tank bottom, a steel ladle stand, a tank cover, and a reinforcing board.

A method for smelting low-phosphorus high-manganese steel based on reduction dephosphorization of ferromanganese is provided in the present application, relating to the technical field of high-manganese steel smelting, where the dephosphorization of ferromanganese is carried out under reducing atmosphere conditions through mediate-frequency induction furnace to obtain molten ferromanganese with lower phosphorus content, which is subsequently mixed with low phosphorus molten steel obtained by smelting in oxidative period of electric arc furnace in LF ladle refining furnace to make the Mn content of steel reach the requirement of high-manganese steel, and smelting is carried out under the condition of reducing atmosphere by adjusting the composition and temperature of the molten steel to meet the requirements of the target composition of the steel grade before tapping the steel.