This hot-rolled steel sheet has a predetermined chemical composition, in which in a case where the thickness is denoted by t, a metallographic structure at a t/4 position from the surface includes, by area fraction, 77.0% to 97.0% of bainite or tempered martensite, 0% to 5.0% of ferrite, 0% to 5.0% of pearlite, 3.0% or more of residual austenite, and 0% to 10.0% of martensite, in the metallographic structure, the average grain size excluding the residual austenite is 7.0 μm or less, the average number density of iron-based carbides having a diameter of 20 nm or more is 1.0×10.sup.6 carbides/mm.sup.2 or more, a tensile strength is 980 MPa or more, and an average Ni concentration on the surface is 7.0% or more.

This hot-rolled steel sheet has a predetermined chemical composition, in which in a case where the thickness is denoted by t, a metallographic structure at a t/4 position from the surface includes, by area fraction, 77.0% to 97.0% of bainite or tempered martensite, 0% to 5.0% of ferrite, 0% to 5.0% of pearlite, 3.0% or more of residual austenite, and 0% to 10.0% of martensite, in the metallographic structure, the average grain size excluding the residual austenite is 7.0 μm or less, the average number density of iron-based carbides having a diameter of 20 nm or more is 1.0×10.sup.6 carbides/mm.sup.2 or more, a tensile strength is 980 MPa or more, and an average Ni concentration on the surface is 7.0% or more.

The disclosure relates to the technical field of sintered type NdFeB permanent magnets, in particular to a low-cost rare earth magnet and manufacturing method. There is provided a method of preparing a high-coercivity, sintered NdFeB magnet including cerium comprising the following steps:

(S1) Providing alloy flakes composed of R.sub.xT.sub.(1-x-y-z)B.sub.yM.sub.z;

(S2) Mixing the alloy flakes, a low melting point powder, and a lubricant, then subjecting the mixture to a hydrogen embrittlement process followed in this order by pulverizing the process product to an alloy powder by jet milling, magnetic field orientation molding of the alloy powder to obtain a blank, sintering and aging treatment the blank;

(S3) Coating a film composed of a diffusion source of formula R1.sub.xR2.sub.yH.sub.zM.sub.1-x-y-z on the sintered NdFeB magnet; and

(S4) Performing a diffusion heat treatment, followed by aging the sintered NdFeB magnet to obtain the low-cost rare earth magnet.

The disclosure relates to the technical field of sintered type NdFeB permanent magnets, in particular to a low-cost rare earth magnet and manufacturing method. There is provided a method of preparing a high-coercivity, sintered NdFeB magnet including cerium comprising the following steps:

(S1) Providing alloy flakes composed of R.sub.xT.sub.(1-x-y-z)B.sub.yM.sub.z;

(S2) Mixing the alloy flakes, a low melting point powder, and a lubricant, then subjecting the mixture to a hydrogen embrittlement process followed in this order by pulverizing the process product to an alloy powder by jet milling, magnetic field orientation molding of the alloy powder to obtain a blank, sintering and aging treatment the blank;

(S3) Coating a film composed of a diffusion source of formula R1.sub.xR2.sub.yH.sub.zM.sub.1-x-y-z on the sintered NdFeB magnet; and

(S4) Performing a diffusion heat treatment, followed by aging the sintered NdFeB magnet to obtain the low-cost rare earth magnet.

The disclosure relates to a method of preparing a low-heavy rare earth magnet comprising the following steps: S1, smelting and strip casting of the raw materials of a NdFeB alloy to obtain a NdFeB alloy sheets, and mechanically crushing the NdFeB alloy sheets into flaky alloy sheets; S2, mechanically mixing the flaky alloy sheets, a low melting point powder and a lubricant to obtain a mixture, followed by hydrogen absorption and dehydrogenation treatment of the mixture and jet milling of the product to obtain a NdFeB magnet powder; S3, pressing, forming and sintering the NdFeB magnet powder to obtain a sintered NdFeB magnet; S4, mechanically processing the sintered NdFeB magnet to a desired shape, and then forming a diffusion source film on the surface of the sintered NdFeB magnet; and S5, performing a diffusion process and aging to obtain the low-heavy rare earth magnet.

The disclosure relates to a method of preparing a low-heavy rare earth magnet comprising the following steps: S1, smelting and strip casting of the raw materials of a NdFeB alloy to obtain a NdFeB alloy sheets, and mechanically crushing the NdFeB alloy sheets into flaky alloy sheets; S2, mechanically mixing the flaky alloy sheets, a low melting point powder and a lubricant to obtain a mixture, followed by hydrogen absorption and dehydrogenation treatment of the mixture and jet milling of the product to obtain a NdFeB magnet powder; S3, pressing, forming and sintering the NdFeB magnet powder to obtain a sintered NdFeB magnet; S4, mechanically processing the sintered NdFeB magnet to a desired shape, and then forming a diffusion source film on the surface of the sintered NdFeB magnet; and S5, performing a diffusion process and aging to obtain the low-heavy rare earth magnet.

Provided is a steel sheet and a method for manufacturing the same, the steel sheet, which can be used for automobile parts and the like, having superb bendability, and excellent balance of strength and ductility and of strength and hole expansion ratio.

Provided is a steel sheet which can be used for automobile parts and the like, and relates to a steel sheet having an excellent balance of strength and ductility, an excellent balance of strength and hole expansibility and excellent bending workability, and a method for manufacturing same.

The invention relates to a method for producing a steel material, particularly a corrosion-resistant steel material for pumps and similar, in which a steel corresponding to the following analysis (in wt. %) is smelted: C<0.050; Si<0.70; Mn<1.00; P<0.030; S<0.010; Cr=14-15.50; Mo=0.30-0.60; Ni=4.50-5.50; V<0.20; W<0.20; Cu=2.50-4.00; Co<0.30; Ti<0.05; Al<0.05; Nb<0.05; Ta<0.05; N<0.05.

Disclosed in the present invention are a heavy rare earth alloy, neodymium-iron-boron permanent magnet material, a raw material, and a preparation method. The heavy rare earth alloy comprises the following components: RH: 30-100 mas %, not including 100 mas %; X, 0-20 mas %, not including 0; B: 0-1.1 mas %; and Fe and/or Co: 15-69 mas %, RH comprising one or more heavy rare earth elements in Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc, and X being Ti and/or Zr. When the heavy rare earth alloy of the present invention is used as a sub-alloy to prepare the neodymium-iron-boron permanent magnet material, a high utilization rate of heavy rare earth is achieved, so that the coercivity can also be greatly improved while the neodymium-iron-boron permanent magnet material maintains high remanence.