A flat steel product for hot forming may be produced from a steel substrate that includes a steel comprising 0.1-3% by weight Mn and up to 0.01% by weight B, along with a protective coating that is applied to the steel substrate. The protective coating may be based on Al and may contain up to 20% by weight of other alloy elements. Also disclosed are methods for producing such flat steel products, steel components, and methods for producing steel components. Absorption of hydrogen is minimized during heating necessary for hot forming. This is achieved at least in part through an alloy constituent of 0.1-0.5% by weight of at least one alkaline earth or transition metal in the protective coating, wherein an oxide of the alkaline earth or transition metal is formed on an outer surface of the protective coating during hot forming of the flat steel product.

An apparatus of size correction for a hot stamping component is provided. The apparatus includes a jig frame and a plurality of attaching units disposed on the jig frame to rotate in an anteroposterior direction and support a hot stamping component including a quenched component which is partially quenched along the jig frame in the anteroposterior direction. A plurality of clamping units disposed on the jig frame and configured to clamp the hot stamping component. A plurality of measurement units mounted on the jig frame and measure a height of the quenched component based on a predetermined zero base. A plurality of correction units are mounted in front of the jig frame corresponding to the quenched component of the hot stamping component. A force is applied to the quenched component in a vertical direction based on the height size, measured by the measurement unit to adjust the height.

A bolt is provided that has high strength and excellent hydrogen embrittlement resistance characteristics. A bolt according to an embodiment of the present invention consists of, in mass %, C: 0.32 to 0.39%, Si: 0.15% or less, Mn: 0.40 to 0.65%, P: 0.020% or less, S: 0.020% or less, Cr: 0.85 to 1.25%, Al: 0.005 to 0.060%, Ti: 0.010 to 0.050%, B: 0.0010 to 0.0030%, N: 0.0015 to 0.0080%, O: 0.0015% or less, Mo: 0 to 0.05%, V: 0 to 0.05%, Cu: 0 to 0.50%, Ni: 0 to 0.30%, and Nb: 0 to 0.05%, with the balance being Fe and impurities. The bolt satisfies Formula (1) and Formula (2), and has a tensile strength of 1000 to 1300 MPa and satisfies Formula (3).
4.910C+Si+2Mn+Cr+4Mo+5V6.1(1)
Mn/Cr0.55(2)
[dissolved Cr]/Cr0.70(3)

A bolt is provided that has high strength and excellent hydrogen embrittlement resistance characteristics. A bolt according to an embodiment of the present invention consists of, in mass %, C: 0.32 to 0.39%, Si: 0.15% or less, Mn: 0.40 to 0.65%, P: 0.020% or less, S: 0.020% or less, Cr: 0.85 to 1.25%, Al: 0.005 to 0.060%, Ti: 0.010 to 0.050%, B: 0.0010 to 0.0030%, N: 0.0015 to 0.0080%, O: 0.0015% or less, Mo: 0 to 0.05%, V: 0 to 0.05%, Cu: 0 to 0.50%, Ni: 0 to 0.30%, and Nb: 0 to 0.05%, with the balance being Fe and impurities. The bolt satisfies Formula (1) and Formula (2), and has a tensile strength of 1000 to 1300 MPa and satisfies Formula (3).
4.910C+Si+2Mn+Cr+4Mo+5V6.1(1)
Mn/Cr0.55(2)
[dissolved Cr]/Cr0.70(3)

A manufacturing process includes depositing a clad layer having a thickness greater than about 0.5 mm (0.02 in) on a surface of the component by hardfacing, and creating a heat affected zone directly below the clad layer due to the depositing. The heat affected zone may be a region of the component where a lowest hardness is lower than a base hardness of the component below the heat affected zone. The method may also include heat treating the component after the deposition such that the lowest hardness in the heat affected zone is restored to within about 15% of the base hardness of the component.

A gas turbine disk material according to the present invention contains: C: from 0.05 to 0.15%; Ni: from 0.25 to 1.50%; Cr: from 9.0 to 12.0%; Mo: from 0.50 to 0.90%; W: from 1.0 to 2.0%; V: from 0.10 to 0.30%; Nb: from 0.01 to 0.10%; Co: from 0.01 to 4.0%; B: from 0.0005 to 0.010%; N: from 0.01 to 0.05%; Mn: 0.40% or less; Si: 0.10% or less; and Al: 0.020% or less. A balance is of Fe and unavoidable impurities. Additionally, as a heat treatment method, a quenching temperature of a forged material having the component composition is set within a range from 1050 to 1150 C.

A gas turbine disk material according to the present invention contains: C: from 0.05 to 0.15%; Ni: from 0.25 to 1.50%; Cr: from 9.0 to 12.0%; Mo: from 0.50 to 0.90%; W: from 1.0 to 2.0%; V: from 0.10 to 0.30%; Nb: from 0.01 to 0.10%; Co: from 0.01 to 4.0%; B: from 0.0005 to 0.010%; N: from 0.01 to 0.05%; Mn: 0.40% or less; Si: 0.10% or less; and Al: 0.020% or less. A balance is of Fe and unavoidable impurities. Additionally, as a heat treatment method, a quenching temperature of a forged material having the component composition is set within a range from 1050 to 1150 C.

A heat-treated steel material is provided having strength of 1.800 GPa or more. The heat-treated steel material includes a chemical composition represented by, in mass %: C: 0.05% to 0.30%; Mn: 2.0% to 10.0%; Cr: 0.01% to 1.00%; Ti: 0.010% to 0.100%; B: 0.0010% to 0.0100%; Si: 0.08% or less; P: 0.050% or less; S: 0.0500% or less; N: 0.0100% or less; Ni: 0% to 2.0%; each of Cu, Mo, and V: 0% to 1.0%; each of Al and Nb: 0% to 1.00%; and the balance: Fe and impurities. 4612[C]+102[Mn]+6051800 is satisfied where [C] denotes a C content and [Mn] denotes a Mn content. The heat-treated steel material includes a microstructure in which 90 volume % or more is formed of martensite, and a dislocation density in the martensite is equal to or more than 9.010.sup.15 m.sup.2.

A heat-treated steel material is provided having strength of 1.800 GPa or more. The heat-treated steel material includes a chemical composition represented by, in mass %: C: 0.05% to 0.30%; Mn: 2.0% to 10.0%; Cr: 0.01% to 1.00%; Ti: 0.010% to 0.100%; B: 0.0010% to 0.0100%; Si: 0.08% or less; P: 0.050% or less; S: 0.0500% or less; N: 0.0100% or less; Ni: 0% to 2.0%; each of Cu, Mo, and V: 0% to 1.0%; each of Al and Nb: 0% to 1.00%; and the balance: Fe and impurities. 4612[C]+102[Mn]+6051800 is satisfied where [C] denotes a C content and [Mn] denotes a Mn content. The heat-treated steel material includes a microstructure in which 90 volume % or more is formed of martensite, and a dislocation density in the martensite is equal to or more than 9.010.sup.15 m.sup.2.

A high-strength screw (1) includes a head (2) and a threaded portion (5) including a thread (6) and a thread end (9) facing away from the head (2) in an axial direction. The threaded portion (5) includes an unhardened portion (12) starting at the thread end (9) and extending in an axial direction. The unhardened portion (12) has a hardness being reduced compared to an axial middle portion (11) of the threaded portion (5).