A tube assembly includes at least first and second tubes configured for coupling at respective ends. The first and second tubes each include a base material, and a weld interface at the respective end. The weld interface is proximate to an inner diameter and an outer diameter of the first and second tubes, and includes a weld interface segment extending therebetween. A work hardened weld assembly couples the base material of each of the first and second tubes. The work hardened weld assembly includes a weld fusion zone between the weld interfaces of the first and second tubes and the weld interface segments of the first and second tubes. The weld fusion zone is work hardened and at least the weld interface segments of the first and second tubes are work hardened between the work hardened weld fusion zone and the base material of the first and second tubes.

Tube having a length of more than 10 m suitable for high-pressure applications with internal pressure of 2 bar or more, and which is not afflicted with disadvantages exhibited by tubes produced by conventional drawing or cold pilger milling methods. The tube has a wall thickness equal to or larger than the internal diameter, an axial length of 12 m or more, a tensile strength Rm of 850 N/mm.sup.2 or more, and a mean roughness index Ra of the inner wall surface of 0.8 ?m or less. Furthermore, a method of manufacturing such a tube forms a hollow into a tubular intermediate in a first forming step according to the cold forming method, the tubular intermediate thus obtained is annealed, and the annealed tubular intermediate is formed into a tube in a second forming step according to the cold forming method.

A steel pipe for pressure piping subjected to autofrettage has an average hardness at its outer layer region of 1.20 times or more of an average hardness at its inner layer region. When an outer diameter is D, and an inner diameter is d, a measured value of a residual stress at an outer surface is denoted by ?.sub.o1, a measured value of a residual stress at an outer surface after halving is denoted by ?.sub.o2, and a measured value of a residual stress at an inner surface after the halving is denoted by ?.sub.i2, an estimated value ?.sub.i1 of a residual stress at the inner surface of the steel pipe is determined by [?.sub.i1=(??.sub.i2)/(A?(t/T).sup.2?1)], [t/T=((?.sub.o2??.sub.o1)/(A?(?.sub.o2??.sub.o1)?C??.sub.i2)).sup.1/2], [A=3.9829? exp(0.1071?(D/d).sup.2)], and [C=?3.3966?exp(0.0452?(D/d).sup.2)] is ?150 MPa or less.

A method for producing a component from a blank made of a medium manganese steel having 4 to 12 wt. % Mn and a TRIP effect at room temperature, in which method the blank is mechanically cut to make a prepared blank having the desired dimensions, cut edges are produced on the prepared blank by means of mechanical cutting, and the prepared blank with the cut edges is cold-formed to obtain the component at room temperature or at a temperature above room temperature but below 60 C. The method is distinguished by cost-effective production, improved formability with reduced cracking at the formed cut edges, while simultaneously reducing the forming forces. The mechanical cutting is performed at a pre-heating temperature in the range of 60 C. to less than 250 C.

Disclosed in the present specification are: a high-strength wire rod for cold heading, having superior heat treatment characteristics and resistance of hydrogen-delayed fracture characteristics, the rod being applicable to a bolt, etc.; a heat-treated component; and a method for manufacturing the same. According to an exemplary embodiment, the high-strength wire rod for cold heading with superior heat treatment characteristics and resistance of hydrogen-delayed fracture characteristics comprises, by wt %, 0.3-0.6% of C, 0.05-0.3% of Si, 0.2-1.0% of Mn, 0.5-2.0% of Cr, 0.5-2.0% of Mo, 0.02-0.05% of Al, 0.01-0.03% of N, and Fe and other impurities as the balance, and has a microstructure comprising, by area fraction, 80% or more of bainite, 1-15% of pearlite and 0.1-2% of martensite, and comprises 210.sup.19/m.sup.3 or more of aluminum nitride having a diameter of 5-50 nm.

A metal structure includes an alloy material containing structural deformation twins embedded during a manufacturing process of the alloy material along defined directions, a defined deformation sequence, and defined strain levels. The embedded structural deformation twins mitigate failure and fracture in the alloy material.

A metal structure includes an alloy material containing structural deformation twins embedded during a manufacturing process of the alloy material along defined directions, a defined deformation sequence, and defined strain levels. The embedded structural deformation twins mitigate failure and fracture in the alloy material.

The tool (10) for textiles according to the invention consists of chromium steel, into which carbon has been embedded in locally varying amounts during a carbonizing process. Thermal treatment achieves a formation of martensite with the maximum achievable hardness, in particular in those zones in which larger carbon fractions have been introduced. A tool for textiles with zones of differing hardnesses can thus be produced without having to subject the individual zones with differing hardnesses to different process conditions during the production process. The hardness is controlled on the basis of the degree of deformation of the tool for textiles.

A superaustenitic material is provided for use in chemical plant construction or in oilfield or gas field technology. The material resists corrosion, in particular corrosion in mediums with high chloride concentrations and sulfuric acid.

A drive shaft includes a first annular wall and a second annular wall joined together via a friction-welded portion. The first annular wall and the second annular wall have outer diameters of 30 to 50 mm and wall thicknesses of 3 to 5 mm. A burr created at the friction-welded portion has a connection radius of greater than or equal to 0.5 mm, a base radius of greater than or equal to 0.5 mm, a burr base angle of less than or equal to 40?, and a burr slope length of 0.2 to 5 mm.