A cold-rolled and heat-treated steel sheet having a microstructure of, in surface fraction: between 10% and 30% of retained austenite, said retained austenite being present as films having an aspect ratio of at least 3 and as Martensite Austenite islands, less than 8% of such Martensite Austenite islands having a size above 0.5 μm, at most 10% of fresh martensite and
recovered martensite containing precipitates of at least one element chosen among niobium, titanium and vanadium. A manufacturing method thereof is also provided.

A cooling unit includes a unit main body including a bottom portion, a peripheral wall portion rising from the peripheral edge of the bottom portion, and a sealing body for sealing an opening of the unit main body. The unit main body is joined to the sealing body through a plasticized region, and a void is formed at a position close to the unit main body with respect to a center of the plasticized region.

A welding and deburring system is provided for joining first and second work pieces to one another. The system includes a friction stir welding tool for joining the first and second work pieces to one another at a weld. The system further includes a deburring tool attached to the friction stir welding tool and removing a material flash generated at the weld. The system further includes one or more nozzles disposed in a fixed position relative to the friction stir welding tool, with the nozzles directing a cryogenic fluid to at least one of the friction stir welding tool, the deburring tool, the first work piece, the second work piece, and the weld.

A double-sided friction stir welding method, methods for producing a cold-rolled steel strip and a coated steel strip, a double-sided friction stir welding apparatus, and facilities for producing a cold-rolled steel strip and a coated steel strip. The double-sided friction stir welding method includes pressing two rotating tools, which are disposed on a first surface and a second surface of a butt portion or overlap portion of the steel strips, against the butt portion or overlap portion of steel strips and moving the rotating tools in the welding direction while rotating the rotating tools in opposite directions to each other, so that an unwelded portion of the steel strips is softened by frictional heat generated between the rotating tools and the unwelded portion of the steel strips, and the softened portion is stirred with the rotating tools to generate plastic flow so as to weld the steel strips together.

A dissimilar material solid phase bonding method is disclosed wherein one member and another member having different compositions are brought into contact with one another by way of an insert material to form an interface (1) to be bonded, at which the one member and the insert material are in contact with one another, and an interface (2) to be bonded, at which the other member and the insert material are in contact with one another; the temperature of the interface (1) to be bonded and the interface (2) to be bonded is raised by means of frictional heat and/or by electrical heating; a bonding pressure (1) is applied substantially perpendicular to the interface (1) to be bonded; a bonding pressure (2) is applied substantially perpendicular to the interface (2) to be bonded; and the bonding pressure (1) and the bonding pressure (2) are set to different values.

A dissimilar material solid phase bonding method is disclosed wherein one member and another member having different compositions are brought into contact with one another by way of an insert material to form an interface (1) to be bonded, at which the one member and the insert material are in contact with one another, and an interface (2) to be bonded, at which the other member and the insert material are in contact with one another; the temperature of the interface (1) to be bonded and the interface (2) to be bonded is raised by means of frictional heat and/or by electrical heating; a bonding pressure (1) is applied substantially perpendicular to the interface (1) to be bonded; a bonding pressure (2) is applied substantially perpendicular to the interface (2) to be bonded; and the bonding pressure (1) and the bonding pressure (2) are set to different values.

A value stream method of manufacturing a plurality of vehicle structural rails includes feeding a coil of aluminum alloy sheet into a roll forming machine and forming a tubular shape with a seam, bobbin tool-friction stir welding the seam of the tubular shape and forming a welded tubular shape with a welded seam, cutting the welded tubular shape into a plurality of tubular sections, tube bending each of the plurality of tubular sections and forming a plurality of bent tubular sections, and hydroforming each of the plurality of bent tubular sections and forming a plurality of structural rails. The coil of aluminum alloy sheet may or may not be pre-treated and/or lubricated.

In some implementations, an apparatus comprises a pipe, a stud that is forge-welded to the pipe, creating a forge-welded stud, a bracket that is operably coupled to the forge-welded stud, and a ladder support operably coupled to the bracket.

Provided is a joining method that can prevent a plastic flowing material from flowing out from a butt section and that can reduce the thickness and weight of metal members. The joining method is for joining a first metal member and a second metal member by using a rotary tool comprising a stirring pin, and is characterized in that: the stirring pin comprises a flat surface perpendicular to the rotation axis of the rotary tool and comprises a protruding section protruding from the flat face; and in a friction stirring step, the flat surface is brought into contact with the first metal member and the second metal member, and a front end face of the protruding section is inserted deeper than an upper overlapping section to join an upper front butt section and the upper overlapping section.

A joining system (100) of the present invention is for joining a joining target (W) including first, second, and third members (W1), (W2), (W3), and includes a welder (101), a friction stir welding machine (102), and a controller (110) that: (A) causes the welder (101) to weld the second and third members (W2), (W3); (B), after (A), causes the joining target (W) to be placed at the friction stir welding machine (102) so that the first member (W1) is opposed to a distal end of a tool (10); and (C), after (B), controls a linear motion driver (7) and a rotation driver (8) so as to, while pressing the distal end of the tool (10) to the joining target (W), rotate the tool (10) around an axis, so that the softened second and third members (W2), (W3) intrude into the softened first member (W1), thus joining the joining target (W).