A high-entropy alloy having ultra-high strength and high hydrogen embrittlement resistance due to formation of a microstructure at a low strain may be produced without a severe plastic deformation.

A method for producing the high-entropy alloy includes (a) annealing and homogenizing an initial alloy material at 1000 to 1200 C. for 1 to 24 hours; and (b) rolling the annealed and homogenized initial alloy material into a rod, at a cryogenic temperature of 100 to 200 C. while pressing the initial alloy material in multi-axial directions at a strain of 0.4 to 1.2, thereby to produce the high-entropy alloy having intersecting twins as a microstructure, and secondary fine twins formed in the intersecting twins, wherein the initial alloy material contains Co of 5 to 35%, Cr of 5 to 35%, Fe of 5 to 35%, Mn of 5 to 35%, and Ni of 5 to 35%, based on weight %.

A high-entropy alloy having ultra-high strength and high hydrogen embrittlement resistance due to formation of a microstructure at a low strain may be produced without a severe plastic deformation.

A method for producing the high-entropy alloy includes (a) annealing and homogenizing an initial alloy material at 1000 to 1200 C. for 1 to 24 hours; and (b) rolling the annealed and homogenized initial alloy material into a rod, at a cryogenic temperature of 100 to 200 C. while pressing the initial alloy material in multi-axial directions at a strain of 0.4 to 1.2, thereby to produce the high-entropy alloy having intersecting twins as a microstructure, and secondary fine twins formed in the intersecting twins, wherein the initial alloy material contains Co of 5 to 35%, Cr of 5 to 35%, Fe of 5 to 35%, Mn of 5 to 35%, and Ni of 5 to 35%, based on weight %.

Provided is a shaping device for a roller electrode for seam welding that prepares shapes for a first roller electrode and a second roller electrode attached to an arm of a robot. This shaping device is provided independently from the robot and disposed within rotational range of the arm, and is provided with a first roller and a second roller that are disposed on a line orthogonal to a line joining the rotational centers of the first and second roller electrodes and are in contact with the outer circumferences of the first and second roller electrodes.

Provided is a shaping device for a roller electrode for seam welding that prepares shapes for a first roller electrode and a second roller electrode attached to an arm of a robot. This shaping device is provided independently from the robot and disposed within rotational range of the arm, and is provided with a first roller and a second roller that are disposed on a line orthogonal to a line joining the rotational centers of the first and second roller electrodes and are in contact with the outer circumferences of the first and second roller electrodes.

An apparatus (100) for applying pressure to at least a portion of an edge surface (192), which bridges opposing faces (194) of a workpiece (190), comprises a frame (110), a first roller (120), a second roller (130), a rotation-control member (140), a first biasing member (150), and a second biasing member (160). The first roller (120) and the second roller (130) are coupled to the frame (110), rotatable relative to the frame (110) about a first pivot axis (125), and translationally fixed relative to the frame (110). The rotation-control member (140) is movable relative to the frame (110), controlling rotation of the first roller (120) and the second roller (130) relative to the frame (110). The first biasing member (150) is coupled to the frame (110) and is configured to operate in tension. The second biasing member (160) is positioned, in compression, between the frame (110) and the rotation-control member (140).

An apparatus (100) for applying pressure to at least a portion of an edge surface (192), which bridges opposing faces (194) of a workpiece (190), comprises a frame (110), a first roller (120), a second roller (130), a rotation-control member (140), a first biasing member (150), and a second biasing member (160). The first roller (120) and the second roller (130) are coupled to the frame (110), rotatable relative to the frame (110) about a first pivot axis (125), and translationally fixed relative to the frame (110). The rotation-control member (140) is movable relative to the frame (110), controlling rotation of the first roller (120) and the second roller (130) relative to the frame (110). The first biasing member (150) is coupled to the frame (110) and is configured to operate in tension. The second biasing member (160) is positioned, in compression, between the frame (110) and the rotation-control member (140).

In a rolled steel bar or rolled wire rod for a cold-forged component having a predetermined chemical composition, Y1 represented by Y1=[Mn][Cr] and Y2 represented by Y2=0.134(D/25.4(0.50[C]))/(0.50[C]) satisfy Y1>Y2, the tensile strength is 750 MPa or less, an internal structure is a ferrite-pearlite structure, and the ferrite fraction in the internal structure is 40% or greater. AMOUNT IS 0.30%

In a rolled steel bar or rolled wire rod for a cold-forged component having a predetermined chemical composition, Y1 represented by Y1=[Mn][Cr] and Y2 represented by Y2=0.134(D/25.4(0.50[C]))/(0.50[C]) satisfy Y1>Y2, the tensile strength is 750 MPa or less, an internal structure is a ferrite-pearlite structure, and the ferrite fraction in the internal structure is 40% or greater. AMOUNT IS 0.30%

In a rolled steel bar or rolled wire rod for a cold-forged component having a predetermined chemical composition, Y1 represented by Y1=[Mn][Cr] and Y2 represented by Y2=0.134(D/25.4(0.50[C])/(0.50[C]) satisfy Y1>Y2, the tensile strength is 750 MPa or less, an internal structure is a ferrite-pearlite structure, and the ferrite fraction in the internal structure is 40% or greater.

In a rolled steel bar or rolled wire rod for a cold-forged component having a predetermined chemical composition, Y1 represented by Y1=[Mn][Cr] and Y2 represented by Y2=0.134(D/25.4(0.50[C])/(0.50[C]) satisfy Y1>Y2, the tensile strength is 750 MPa or less, an internal structure is a ferrite-pearlite structure, and the ferrite fraction in the internal structure is 40% or greater.