The present disclosure relates generally to a method for improving the performance of sintered NdFeB magnet. A method of preparing a sintered NdFeB magnet therefore comprises the steps of: a) preparing alloy flakes from a raw material of the NdFeB magnet by a strip casting process; and b) preparing a coarse alloy powder from the alloy flakes by a hydrogen decrepitation process, the hydrogen decrepitation process including treatment of the alloy flakes under a hydrogen pressure of 0.10 MPa to 0.25 MPa for a duration of 1 to 3.5 hours, then degassing the hydrogen at a predetermined temperature between 300° C. to 400° C. for a duration time of 0.5 to 5 hours, and then mixing the resulting coarse alloy powder with a lubricant.

A soft magnetic powder contains a particle having a composition represented by Fe.sub.xCu.sub.aNb.sub.b(Si.sub.1-yB.sub.y).sub.100-x-a-b, and 0.3≤a≤2.0, 2.0≤b≤4.0, and 72.5≤x≤75.5, and y is a number satisfying f(x)≤y≤0.99, and f(x)=(4×10.sup.−34)×17.56. The particle includes a crystal grain having a grain size of 1.0 nm to 30.0 nm, a Cu segregation portion, and a crystal grain boundary. A content proportion of the crystal grain is 30% or more. When the Cu segregation portion positioned in a surface layer portion and having a grain size of 1.0 nm to 5.0 nm is referred to as a first Cu segregation portion, and the Cu segregation portion positioned in an inner portion and having a grain size of 3.0 nm to 10.0 nm is referred to as a second Cu segregation portion, a number proportion of the first Cu segregation portion is 80% or more, and a number proportion of the second Cu segregation portion is 80% or more.

There is provided a hot-stamped member or a steel sheet for hot stamping having a chemical composition including, in mass %, C: 0.25% or more and 0.55% or less, Si: 0.001% or more and 2.0% or less, Mn: 0.3% or more and 3.0% or less, P: 0.02% or less, S: 0.003% or less, Al: 0.005% or more and 1.0% or less, Cr: 0% or more and 1.0% or less, Mo: 0% or more and 1.0% or less, N: 0.02% or less, Ca: 0% or more and 0.0010% or less, B: 0.0005% or more and 0.01% or less, one or two or more selected from the group consisting of Ti: 0.005% or more and 0.5% or less, Nb: 0.005% or more and 0.5% or less, V: 0.005% or more and 0.5% or less, and Zr: 0.005% or more and 0.5% or less, and Ni+Cu+Sn: 0% or more and 2% or less, and a remainder consisting of Fe and impurities.

An R-T-B based permanent magnet including R.sub.2T.sub.14B main phase crystal grains and a grain boundary. R represents one or more rare earth elements, T represents one or more iron group elements essentially including Fe or Fe and Co, and B represents boron. In a cross-section parallel to the alignment direction of the R-T-B based permanent magnet, the coverage of the R.sub.2T.sub.14B main phase crystal grains is 50.0% or more, and the area ratio of the R.sub.2T.sub.14B main phase crystal grains is 92.0% or more.

The present invention related to a structural steel sheet having excellent seawater resistance and having excellent corrosion resistance in environments in which corrosion is accelerated by seawater, and a method for manufacturing same.

A non-oriented electrical steel sheet according to an embodiment of the present invention includes, in wt%, Si: 2.2 to 4.5 %, Mn: 0.5 % or less (excluding 0 %), AI: 0.001 to 0.5 %, Sn: 0.07 to 0.25 %, and N: 0.0010 to 0.0090 %, and the balance of Fe and inevitable impurities.

A surface layer portion existing in an inner direction from a surface of the steel sheet and a central portion existing inside the surface layer portion are included, and the central portion includes N at 0.005 wt% or less, and the surface layer portion further includes N at 0.001 wt% or more compared to the central portion; and the surface layer portion has an average grain size of 60 .Math.m or less, while the central portion has an average grain size of 70 to 300 .Math.m.

The present invention relates to a steel sheet with improved yellowing resistance and phosphatability, wherein the steel sheet contains 0.5% by weight or more of Mn, and contains 0.01 to 10 mg/m.sup.2 of Ca+Mg, 0.01 to 10 mg/m.sup.2 of P, 0.01 to 20 mg/m.sup.2 of C, and 0.05 to 30 mg/m.sup.2 of O as components excluding a steel component on the surface of the steel sheet after pickling, water rinsing, and drying. According to the present invention, in a manufacturing process of the steel sheet, the surface of the steel sheet is subjected to a chemical conversion treatment for improving phosphatability and yellowing resistance in a water-cooling section or a water-washing section, thereby having an effect of improving the surface quality of products using same and various subsequently treated products.

A method for manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention comprises the steps of: hot-rolling a slab to prepare a hot-rolled sheet, the slab containing, in wt %, 2.0 to 6.0% of Si, 0.04 to 0.12% of Mn, 0.001 to 0.022% of N, 0.027 to 0.060% of C, 0.01 to 0.08% of Nb, 0.01% or less of Ti, and the balance of Fe and other inevitable impurities; cold-rolling the hot-rolled sheet to prepare a cold-rolled sheet; and subjecting the primarily recrystallization-annealed cold-rolled sheet to secondary recrystallization annealing.

The present disclosure relates to a thick steel material that can be appropriately used as a line pipe, a sour-resistant material and, more particularly, to a high-strength steel material having excellent sulfide stress corrosion cracking resistance and excellent resistance against propagation of sulfide stress corrosion cracking, and a method of manufacturing the steel material.

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 and an excellent balance of strength and hole expansibility, and excellent bending workability, and a method for manufacturing same.