An example track shoe, cutting edge, or other component of a machine is formed in a heated process, such as hot-rolling followed by air-hardening. The air-hardening process involves cooling the component by flowing air over the component (e.g., air cooling), such that the component is cooled at a controlled rate. During the air-cooling process, such as in the range of about 250° C. to about 1100° C., the component may be machined, such as by shearing, punching, drilling, etc. The machining may form the final shape of the component. As the air-hardening process is completed, and the component approaches room temperature, the component may have at least 5% bainitic crystal composition, and as high as greater than 80% bainitic crystal composition, resulting in relatively high hardness and fracture toughness. The final track shoe may have a hardness between about 40 HRC and 55 HRC.

Provided is a blank made of a steel and comprising at least two protruding regions (313) having an outer edge (311) protruding outward in in-plane directions, in which a softened part (320) is formed at least partially in the protruding regions (313) and the softened part (320) is formed in at least a part of the outer edge of the protruding regions (313), a Vickers hardness of the softened part (320) is lower than a Vickers hardness of a main portion region (310), and the blank comprises at least two of the protruding regions (313) having the softened part (320).

To solve the problem about the difference in temperature increasing rate between an overlapped part and a one-sheet part so as to further improve the corrosion resistance of plating after hot stamping. An overlapped blank for hot stamping includes: a first steel sheet; and at least one second steel sheet connected to a surface of the first steel sheet via a welding point and smaller in area than the first steel sheet, wherein: the first steel sheet is a plated steel sheet having an aluminum-based plated layer on both faces of the first steel sheet, and the second steel sheet is a plated steel sheet having an aluminum-based plated layer on both faces of the second steel sheet; a coating weight of the aluminum-based plated layer on the first steel sheet is W1 (g/m.sup.2) in terms of an average coating weight on both the faces; a coating weight of the aluminum-based plated layer on a surface on a side not in contact with the first steel sheet in the second steel sheet is W2 (g/m.sup.2); and each of the W1 and the W2 is within a range of 20 g/m.sup.2 or more and 120 g/m.sup.2 or less, and satisfies relationships of Expression (1) and Expression (2).

An assembly of an aluminum-based part and a press hardened steel part provided with an alloyed coating including in weight percent, 0.1 to 15.0% silicon, 15.0 to 70% of iron, 0.1 to 20.0% of zinc, 0.1 to 4.0% of magnesium, the balance being aluminum, on at least one of the surfaces thereof placed so as to be in contact with the aluminum-based part.

A shaft part excellent in static torsional strength and torsional fatigue strength containing, by mass %, essential elements of C: 0.35 to 0.70%, Si: 0.01 to 0.40%, Mn: 0.5 to 2.6%, P: 0.050% or less, S: 0.005 to 0.020%, Al: 0.010 to 0.050%, N: 0.005 to 0.025%, and O: 0.003% or less, further containing optional elements, having a balance of Fe and impurities, having a chemical composition satisfying formula (1), having at least one hole at an outer circumferential surface, having a volume ratio (R1) of 4 to 20% of retained austenite at a position of a 2 mm depth from the outer circumferential surface, having a volume ratio of retained austenite at a position of a 2 mm depth from the outer circumferential surface in an axial direction of the hole and at a position of a 20 μm depth from the surface of the hole as R2, and having a reduction rate Δγ of 40% or more of retained austenite found by the formula (A): Δγ=[(R1−R2)/R1]×100: Formula (1): 15.0≤25.9C+6.35Mn+2.88Cr+3.09Mo+2.73Ni≤27.2 (Notations of elements in formula are contents of the elements).

The device has a short production line, and all components are reasonably configured. A multifunctional cooling control device is adopted to integrate high-pressure water descaling and intermediate billet cooling functions, which is simpler and more efficient. Layout of a 4R+(3−4)F rolling mill, four thermos-detectors and short-distance underground coilers are use. The method includes the steps: carrying out continuous casting to manufacture a slab, high-pressure water rotating descaling, rough rolling by a four-stand high reduction rough rolling unit, machining by a drum shear, cooling after high-pressure water descaling in the multifunctional cooling control device, finish rolling by a three-stand or four-stand finish rolling unit, air cooling, dividing coils by a high-speed flying shear, and coiling by underground coilers, wherein temperature monitoring is respectively carried out after rough rolling, before finish rolling, after finish rolling, and before coiling by the underground coiler.

An iron-based alloy composition includes 0.28-0.34% C, max 0.25% Si, max 0.8% Mn, 0.85-0.95% Cr, 1.10-1.50% Ni, 0.41-0.50% Mo, 0.001-0.007% B, 0.002-0.03% Nb, and balanced amount of Fe and inevitable impurities. Moreover, parts with a hardness of at least 480 HB, a tensile strength of at least 1700 MPa, a total elongation of at least 7% and an impact strength of at least 16 J are obtained by the iron-based alloy composition and a production method of the parts.

A metal plate includes a surface including a longitudinal direction of the metal plate and a width direction orthogonal to the longitudinal direction. A surface reflectance by regular reflection of a light is 8% or more and 25% or less. The surface reflectance is measured when the light is incident on the surface at an angle of 45°±0.2°. The light is in at least one plane orthogonal to the surface.

A method for processing a steel plate capable of removing residual strain at a trim edge thereof without causing overheating in areas of the steel plate other than the trim edge. A method of processing a steel plate includes punching a steel plate and disposing heating electrodes in such a way that a trim edge punched in the punching is positioned between electrode surfaces facing each other and then heating a part of the steel plate including the trim edge.

This steel sheet is a steel sheet (100) formed by causing end surfaces of a first sheet material (111) and a second sheet material (113) to abut each other in an in-plane direction and welding the first sheet material (111) and the second sheet material (113) via a strip-shaped welded part (115), and in which a softened part (120) that is softened more than other parts in the welded part (115) is formed in at least a part of the welded part (115), and on a first end surface of the steel sheet in which an end part of the welded part (115) in a longitudinal direction is formed, a region in which the softened part (120) is not formed is provided in at least a part of the end part of the welded part (115) in the longitudinal direction, and a maximum value of a depth of the softened part (120) in a sheet thickness direction is, as a ratio to a sheet thickness of the steel sheet (100), 50% or less.