Abstract: To provide a steel and a manufacturing method thereof that can contribute to achieving both high strength and hydrogen embrittlement resistance. The steel has a chemical composition represented by: C: 0.15% to 0.35%; Si: 0.8% to 2.5%; Mn: 0.8% to 2.5%; Al: 0.03% to 2.0%; N: 0.002% to 0.010%; P: 0.01% or less; S: 0.01% or less; O: 0.01% or less; B: 0.0001% to 0.005%; Nb: 0.0% to 0.05%; Ti: 0.0% to 0.2%; V 0.0% to 0.05%; Mo: 0.0% to 1.0%; Cr: 0.0% to 1.0%; Ni: 0.01% to 1.0%; Cu: 0.05% to 1.0%; at least one of Ca, Mg and REM: 0.0005% to 0.01%; and the balance: Fe and impurities, and has a martensite phase or/and a bainite phase in which ?-carbide is dispersedly precipitated.

Abstract: A structure of a two-phase steel is controlled by subjecting a steel containing C: 0.05-0.80 mass % to a strain work in a true strain quantity of not less than 0.1 at a temperature zone of &agr;-phase or &ggr;-phase and then applying a magnetic field of 0.1-20 T thereto within a temperature range forming a two-phase zone of &agr;-phase and &ggr;-phase.

Abstract: A structure of a two-phase steel is controlled by subjecting a steel containing C: 0.05-0.80 mass % to a strain work in a true strain quantity of not less than 0.1 at a temperature zone of &agr;-phase or &ggr;-phase and then applying a magnetic field of 0.1-20T thereto within a temperature range forming a two-phase zone of &agr;-phase and &ggr;-phase.

Abstract: Magnetic heat treatment of steel, characterized by transforming steel containing about 0.01 to 2.0 mass % of carbon in a magnetic field having a gradient of about 0.1 T/cm or more and about 10 T/cm or less (absolute value) at the Curie point or lower, to effectively refine the microstructure by subjecting the steel to heat treatment in a strong magnetic field having a gradient, followed by advantageously improving the mechanical properties of the steel.

Abstract: This invention provides permanent magnets that are excellent not only in magnetic properties but also corrosion resistance by using two magnetically useful phases, i.e., RE.sub.2 TM.sub.14 B phase having a high residual magnetic flux density and a low melting point RE-TM' phase or RE-TM'-B phase which enhances the sinterability and possesses a cleaning action against grain boundaries of the RE.sub.2 TM.sub.14 B main phase. Further the invention provides a method for forming an electrochemically noble composition as a starting material to prepare a two phase magnet.

Abstract: A corrosion-resistant rare earth metal-transition metal-boron permanent magnet having improved corrosion resistance and excellent magnetic properties, including RE: 10-25 at % (where RE is at least one of Y, Sc and lanthanides), B: 2-20 at % and the remainder being substantially Fe, Co and Ni. In this case, the magnet has an average crystal grain size of 0.1-50 .mu.m and includes a crystal grain boundary phase of RE(Ni.sub.1-x-y Co.sub.x Fe.sub.y) compound having a thickness of not more than 10 .mu.m.

Abstract: A corrosion-resistant rare earth metal-transition metal magnet alloy having excellent coercive force, squareness, corrosion resistance and temperature characteristics is disclosed, which alloy consists of at least one of rare earth element inclusive of Y; B; occasionally at least one of Mg, Al, Si, Ca, Ti, V, Cr, Mn, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Ta and W; and the remainder being transition metals of Fe, Co and Ni.