An alloy which includes at least the following (in % by weight): carbon (C): 0.15%-0.25%; silicon (Si): 0.0%-0.08%; manganese (Mn): 0.03%-0.20%; chromium (Cr): 9.5%-10.5%; molybdenum (Mo): 0.4%-1.0%; tungsten (W): 1.6%-2.4%; cobalt (Co): 2.5%-3.5%; nickel (Ni): 0.0%-0.40%; boron (B): 0.003%-0.02%; nitrogen (N): 0.0%-0.40%; titanium (Ti): 0.02%-0.10%; vanadium (V): 0.10%-0.30%; niobium (Nb): 0.02%-0.08%; copper (Cu): 1.20%-2.10%; and aluminum (Al): 0.003%-0.06%, in particular 0.005%-0.04%; the remainder being iron (Fe).

The steel material according to the present disclosure has a chemical composition consisting of, in mass %, C: 0.20 to 0.35%, Si: 0.05 to 1.00%, Mn: 0.01 to 1.00%, P: 0.025% or less, S: 0.0100% or less, Al: 0.005 to 0.100%, Cr 0.25 to 0.80%, Mo: 0.20 to 2.00%, Ti: 0.002 to 0.050%, B: 0.0001 to 0.0050%, N: 0.0020 to 0.0100% and O: 0.0100% or less, with the balance being Fe and impurities, and satisfying Formula (1). A number density of precipitates having an equivalent circular diameter of 400 nm or more is 0.150 particles/μm.sup.2 or less. The yield strength is within a range of 655 to 965 MPa. A dislocation density ρ is 7.0×10.sup.14 m.sup.−2 or less.
5×Cr—Mo-2×(V+Ti)≤3.00  (1)

The present invention relates to the application of at least partially bainitic or interstitial martensitic heat treatments on steels, often tool steels or steels that can be used for tools. The first tranche of the heat treatment implying austenitization is applied so that the steel presents a low enough hardness to allow for advantageous shape modification, often trough machining. Thus a steel product is obtained which can be shaped with ease and whose hardness can be raised to a higher working hardness with a simple heat treatment at low temperature (below austenitization temperature).

The present invention relates to the application of at least partially bainitic or interstitial martensitic heat treatments on steels, often tool steels or steels that can be used for tools. The first tranche of the heat treatment implying austenitization is applied so that the steel presents a low enough hardness to allow for advantageous shape modification, often trough machining. Thus a steel product is obtained which can be shaped with ease and whose hardness can be raised to a higher working hardness with a simple heat treatment at low temperature (below austenitization temperature).

A ferritic stainless steel with chemical composition includes, in mass %, Cr: 10.5 to 25.0%; Al: 0.01 to 0.20%; Ti: 0.15% to 0.35%; O: 0.0001 to 0.0030%; and Mg: 0.008×[% Al] or more, in which oxysulfide-containing inclusions are present in the steel, a number ratio of the oxysulfide-containing inclusions whose minor axis is 3 μm or more is 5 pieces/mm.sup.2 or less, and a number ratio of the oxysulfide-containing inclusions whose minor axis is 15 μm or more is 0.05 pieces/mm.sup.2 or less. 75% or more of the inclusions whose minor axis is 3 μm or more have an oxysulfide part whose composition satisfies formulae (1) and (2),

CaO+Al.sub.2O.sub.3+MgO≥90%  formula (1),

Al.sub.2O.sub.3/MgO≤1.25  formula (2).

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.

A valve spring which has an excellent fatigue limit is provided. A chemical composition of the valve spring according to the present embodiment contains, in mass %, C: 0.50 to 0.80%, Si: 1.20 to less than 2.50%, Mn: 0.25 to 1.00%, P: 0.020% or less. S: 0.020% or less: Cr: 0.40 to 1.90%, V: 0.05 to 0.60%, Ca: 0.0001 to 0.0050%, and N: 0.0100% or less, with the balance being Fe and impurities. In the valve spring, a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 5000 to 80000 pieces/μm.sup.3, and a numerical proportion of Ca sulfides with respect to a total number of oxide-based inclusions and sulfide-based inclusions is 0.20% or less.

A powder admixture useful for making a sintered valve seat insert includes a first iron-base powder and second iron-base powder wherein the first iron-base powder has a higher hardness than the second iron-base powder, the first iron-base powder including, in weight percent, 1-2% C, 10-25% Cr, 5-20% Mo, 15-25% Co, and 30-60 wt. % Fe, and the second iron-base powder including, in weight %, 1-1.5% C, 3-15% Cr, 5-7% Mo, 3-6% W, 1-1.7% V, and 60-85% Fe. The powder admixture can be sintered to form a sintered valve seat insert optionally infiltrated with copper.

The present invention is to provide a steel plate with physical properties superior to existing steel plates used in fields such as industrial machinery, especially excellent low-temperature impact toughness along with high strength and high hardness, and a method for manufacturing same.

The present invention is to provide a steel plate with physical properties superior to existing steel plates used in fields such as industrial machinery, especially excellent low-temperature impact toughness along with high strength and high hardness, and a method for manufacturing same.