A grain-oriented electrical steel sheet according to an embodiment of the prevent invention comprises: Si: 1.0% to 7.0%, C: 0.005% or less (excluding 0%), P: 0.0010 to 0.1%, Sn: 0.005 to 0.2%, S: 0.0005 to 0.020%, Se: 0.0005 to 0.020% and B: 0.0001 to 0.01% by weight, and the remainder comprising Fe and other inevitable impurities.

A turbine blade designing method is for designing a turbine blade formed using a metal material in which creep including diffusion creep and dislocation creep occurs by heating. The turbine blade designing method includes: acquiring temperature distribution data relating to temperature distribution in the turbine blade to be heated; acquiring creep strength distribution data relating to distribution of the creep strength required for the turbine blade to be heated; from the correlation data, based on the temperature distribution data and the creep strength distribution data, setting the crystal grain size of a high-temperature portion that is the diffusion creep temperature range of the turbine blade to a size coarser than the reference crystal grain size, and setting the crystal grain size of a low-temperature portion that is the dislocation creep temperature range of the turbine blade to a size finer than the reference crystal grain size.

A turbine blade designing method is for designing a turbine blade formed using a metal material in which creep including diffusion creep and dislocation creep occurs by heating. The turbine blade designing method includes: acquiring temperature distribution data relating to temperature distribution in the turbine blade to be heated; acquiring creep strength distribution data relating to distribution of the creep strength required for the turbine blade to be heated; from the correlation data, based on the temperature distribution data and the creep strength distribution data, setting the crystal grain size of a high-temperature portion that is the diffusion creep temperature range of the turbine blade to a size coarser than the reference crystal grain size, and setting the crystal grain size of a low-temperature portion that is the dislocation creep temperature range of the turbine blade to a size finer than the reference crystal grain size.

A steel sheet for hot stamping use used as a material for a hot stamped article excellent in strength or bending deformability, having a predetermined chemical composition, having a microstructure containing at least one of lower bainite, martensite, and tempered martensite in an area ratio of 90% or more, having an X-ray random intensity ratio of {112}<111> of the crystal grains forming the above lower bainite, martensite, or tempered martensite of 2.8 or more, having a number density of grain size 50 nm or less cementite or epsilon carbides in the microstructure of 1×10.sup.16/cm.sup.3 or more, and having a grain boundary solid solution ratio Z defined by Z=(mass % of one or both of Nb and Mo at grain boundaries)/(mass % of one or both of Nb and Mo at time of melting) of 0.4 or more.

There is provided a hot forged product having excellent wear resistance and fatigue strength even when the hot forged product is produced with a thermal refining treatment and a case hardening thermal treatment after hot forging omitted, and having a chemical composition consisting of, in mass %, C: 0.45 to 0.70%, Si: 0.01 to 0.70%, Mn: 1.0 to 1.7%, S: 0.01 to 0.1%, Cr: 0.05 to 0.25%, Al: 0.003 to 0.050%, N: 0.003 to 0.02% with the balance being Fe and impurities. The matrix at the depth of 500 μm to 5 mm from an unmachined surface of the forged product is a ferrite-pearlite structure, in which a pro-eutectoid ferrite area fraction is 3% or less or a pearlite structure, and the average diameter of pearlite colonies in the pearlite structure at the depth of 500 μm to 5 mm from the unmachined surface is 5.0 μm or less.

A hot pressed part comprises: a predetermined chemical composition; and a steel microstructure that is a gradient microstructure in which, in a thickness direction, a surface layer is a soft layer, an inside is a hard layer, and a layer between the soft layer and the hard layer is a transition layer.

The present invention provides an annealed steel material having a composition containing, in mass %, 0.28≤C≤0.42, 0.01≤Si≤1.50, 0.20≤Mn≤1.20, 4.80≤Cr≤6.00, 0.80≤Mo≤3.20, 0.40≤V≤1.20, and 0.002≤N≤0.080, with the balance being Fe and unavoidable impurities; in which the annealed steel material has a cross-sectional size of a thickness of 200 mm or more and a width of 250 mm or more, and a hardness of 100 HRB or less; and in which a diameter of a largest ferritic grain observed in a microstructure is 120 μm or less in terms of a perfect circle equivalent, an area ratio of carbides is 3.0% or more and less than 10.5%, and an average particle diameter of the carbides is 0.18 μm or more and 0.29 μm or less.

Disclosed are a continuous heat treatment device and method for a sintered Nd—Fe—B magnet workpiece. The device comprises a first heat treatment chamber, a first cooling chamber, a second heat treatment chamber, and a second cooling chamber continuously disposed in sequence, as well as a transfer system disposed among the chambers to transfer the alloy workpiece or the metal workpiece; both the first cooling chamber and the second cooling chamber adopt a air cooling system, wherein a cooling air temperature of the first cooling chamber is 25° C. or above and differs from a heat treatment temperature of the first heat treatment chamber by at least 450° C.; a cooling air temperature of the second cooling chamber is 25° C. or above and differs from a heat treatment temperature of the second heat treatment chamber by at least 300° C. The continuous heat treatment device and method can improve the cooling rate and production efficiency and improve the properties and consistency of the products.

Disclosed are a device and method for continuously performing grain boundary diffusion and heat treatment, characterized in that the alloy workpiece or the metal workpiece are arranged in a relatively independent processing box together with a diffusion source; the device comprises, in successive arrangement, a grain boundary diffusion chamber, a first cooling chamber, a heat treatment chamber, and a second cooling chamber, and a transfer system provided between various chambers for delivering the processing box; each of the first cooling chamber and the second cooling chamber uses an air cooling system, and the cooling air temperature of the first cooling chamber is above 25° C. and at least differs by 550° C. from the grain boundary diffusion temperature of the grain boundary diffusion chamber; the cooling air temperature of the second cooling chamber is above 25° C. and at least differs by 300° C. from the heat treatment temperature of the heat treatment chamber; and the cooling chamber has a pressure of 50 kPa to 100 kPa. The device provided by the present invention can increase the cooling rate and production efficiency, and improve product consistency.

An example bushing has three portions along its radial direction including an inner portion most proximal to a central hole of the bushing, an outer portion most distal from the center hole, and a core portion between the inner portion and the outer portion. The core portion has a hardness that is less than the hardness of the inner portion or the outer portion of the bushing. The bushing may be formed using high carbon steel, which in some cases may be spheroidal cementite crystal structure. A rough bushing may be formed using the high carbon steel, followed by a direct hardening process, and an induction hardening process on the inner surface most proximal to the central hole of the bushing. The induction hardening on the inner surface may harden the outer portion while tempering the core portion of the bushing.