A separator plate for use as a clutch plate for a multiplate wet clutch is formed of a steel plate. The steel plate has a chemical composition containing, on a basis of percent by mass, C from 0.03 to 0.08%, Si from 0 to 1.0%, Mn from 0.2 to 0.8%, P at 0.03% or less, S at 0.01% or less, and Al at 0.05% or less, so as to satisfy a formula, 5*C %−Si %+Mn %−1.5*Al %<1. In addition, the steel plate has the chemical component containing at least one of Nb from 0.03 to 0.4%, V from 0.01 to 0.3%, and Ti from 0.01 to 0.3%, so as to satisfy a formula, 0.04<(Nb %/1.4)+(V %/1.1)+Ti %<0.3. Then, an average diameter of particles of a carbide as a precipitate is controlled to be from 20 to 100 nm. The plate is formed by heating, hot rolling, winding and forming.

Austempered steel for components requiring high strength and high ductility and/or fracture toughness, which has a silicon content of 3.1 weight-% to 4.4 weight-% and a carbon content of 0.4 weight-% to 0.6 weight-%. The microstructure of the austempered steel is ausferritic or superbainitic.

Austempered steel for components requiring high strength and high ductility and/or fracture toughness, which has a silicon content of 3.1 weight-% to 4.4 weight-% and a carbon content of 0.4 weight-% to 0.6 weight-%. The microstructure of the austempered steel is ausferritic or superbainitic.

Provided in the present application are a rare-earth microalloyed steel and a control process. The steel has a special microstructure, and the microstructure comprises a rare earth-rich nanocluster having a diameter of 1-50 nm. The nanocluster has the same crystal structure type as a matrix. The rare earth-rich nanocluster inhibits the segregation of the elements S, P and As on a grain boundary, and obviously improves the fatigue life of the steel. In addition, a rare-earth solid solution also directly affects a phase change dynamics process so that the diffusion-type phase change starting temperature in the steel changes at least to 2° C., and even changes to 40-60° C. in some kinds of steel, thereby greatly improving the mechanical properties thereof, and providing a foundation for the development of more kinds of high-performance steel.

Provided in the present application are a rare-earth microalloyed steel and a control process. The steel has a special microstructure, and the microstructure comprises a rare earth-rich nanocluster having a diameter of 1-50 nm. The nanocluster has the same crystal structure type as a matrix. The rare earth-rich nanocluster inhibits the segregation of the elements S, P and As on a grain boundary, and obviously improves the fatigue life of the steel. In addition, a rare-earth solid solution also directly affects a phase change dynamics process so that the diffusion-type phase change starting temperature in the steel changes at least to 2° C., and even changes to 40-60° C. in some kinds of steel, thereby greatly improving the mechanical properties thereof, and providing a foundation for the development of more kinds of high-performance steel.

The present invention relates to a high entropy alloy having more improved mechanical properties by controlling contents of additive elements in a NiCoFeMnCr 5-element alloy to control stacking fault energy, thereby controlling stability of a γ austenite phase to control a transformation mechanism, wherein the stacking fault energy is controlled in a composition range of Ni.sub.aCo.sub.bFe.sub.cMn.sub.dCr.sub.e (a+b+c+d+e=100, 1≦a≦50, 1≦b≦50, 1≦c≦50, 1≦d≦50, 10≦e≦25, and 77a−42b−22c+73d−100e+2186≦1500), and thus, the γ austenite phase exhibits a twin-induced plasticity (TWIP) property or a transformation induced-plasticity (TRIP) property in which the γ austenite phase is subjected to phase transformation into an ε martensite phase or an α′ martensite phase, under stress, thereby having improved strength and elongation at the same time to have excellent mechanical properties.

The present invention relates to a high entropy alloy having more improved mechanical properties by controlling contents of additive elements in a NiCoFeMnCr 5-element alloy to control stacking fault energy, thereby controlling stability of a γ austenite phase to control a transformation mechanism, wherein the stacking fault energy is controlled in a composition range of Ni.sub.aCo.sub.bFe.sub.cMn.sub.dCr.sub.e (a+b+c+d+e=100, 1≦a≦50, 1≦b≦50, 1≦c≦50, 1≦d≦50, 10≦e≦25, and 77a−42b−22c+73d−100e+2186≦1500), and thus, the γ austenite phase exhibits a twin-induced plasticity (TWIP) property or a transformation induced-plasticity (TRIP) property in which the γ austenite phase is subjected to phase transformation into an ε martensite phase or an α′ martensite phase, under stress, thereby having improved strength and elongation at the same time to have excellent mechanical properties.

Disclosed is a method for controlling a Ti concentration in a steel when manufacturing a silicon-deoxidized steel comprising 0.1 to 3% by mass of Si and 0.0001 to 0.005% by mass of Al by ladle refining of a molten steel, the method including the step of: adding an oxide including TiO.sub.2 to a slag in a ladle during the ladle refining, wherein the slag produced at end of the ladle refining satisfies formulas (1) to (7) below:

0.5≦CaO/SiO.sub.2≦1.8  (1)

4% by mass≦Al.sub.2O.sub.3≦20% by mass  (2)

MgO≦15% by mass  (3)

1.5% by mass≦TiO.sub.2≦10% by mass  (4)

CaO+SiO.sub.2+Al.sub.2O.sub.3+MgO+TiO.sub.2≧90% by mass  (5)

0.4≦TiO.sub.2/MnO≦5  (6)

1≦TiO.sub.2/T.Fe≦10  (7)

where a compound represented by a chemical formula represents the content of the compound in percent by mass; and T.Fe represents the total concentration, in mass ratio, of Fe contained in Fe oxides in the slag.

A method of treating rare earth metal-bearing permanent magnet scrap, waste or other material in a manner to recover the heavy rare earth metal content separately from the light rare earth metal content. The heavy rare earth metal content can be recovered either as a heavy rare earth metal-enriched iron based alloy or as a heavy rare earth metal based alloy.

A method of treating rare earth metal-bearing permanent magnet scrap, waste or other material in a manner to recover the heavy rare earth metal content separately from the light rare earth metal content. The heavy rare earth metal content can be recovered either as a heavy rare earth metal-enriched iron based alloy or as a heavy rare earth metal based alloy.