A resistance welded steel pipe is provided. A hot-rolled steel sheet having a composition containing, in mass %, C: 0.025 to 0.168%, Si: 0.10 to 0.30%, Mn: 0.60 to 1.90%, and one or at least two selected from Ca, Nb, V, and Ti such that Pcm is 0.20 or less is subjected to continuous cold roll forming to obtain a pipe-shaped body. Tapered grooves are formed in the steel sheet such that the ratio of the tapered portions to the wall thickness of the steel sheet is 10 to 80%. Then end surfaces of the pipe-shaped body are butted against each other and subjected to electric resistance welding. Ultrasonic waves are transmitted toward the electric resistance weld surface such that a beam width is within the range of 0.1 to 4.0 mm, and the reflected waves are used for ultrasonic flaw detection using an ultrasonic flaw detector.

A resistance welded steel pipe is provided. A hot-rolled steel sheet having a composition containing, in mass %, C: 0.025 to 0.168%, Si: 0.10 to 0.30%, Mn: 0.60 to 1.90%, and one or at least two selected from Ca, Nb, V, and Ti such that Pcm is 0.20 or less is subjected to continuous cold roll forming to obtain a pipe-shaped body. Tapered grooves are formed in the steel sheet such that the ratio of the tapered portions to the wall thickness of the steel sheet is 10 to 80%. Then end surfaces of the pipe-shaped body are butted against each other and subjected to electric resistance welding. Ultrasonic waves are transmitted toward the electric resistance weld surface such that a beam width is within the range of 0.1 to 4.0 mm, and the reflected waves are used for ultrasonic flaw detection using an ultrasonic flaw detector.

A high-strength thick-walled electric resistance welded steel pipe has excellent low-temperature toughness and excellent HIC resistance and a yield strength of 400 MPa or more. The steel has a chemical composition consisting of C: 0.025% to 0.084%, Si: 0.10% to 0.30%, Mn: 0.70% to 1.80%, controlled amounts of P, S, Al, N, and O, Nb: 0.001% to 0.065%, V: 0.001% to 0.065%, Ti: 0.001% to 0.033%, and Ca: 0.0001% to 0.0035% on a mass percent basis and the remainder being Fe and incidental impurities, and satisfies Pcm of 0.20 or less.

A high-strength thick-walled electric resistance welded steel pipe has excellent low-temperature toughness and excellent HIC resistance and a yield strength of 400 MPa or more. The steel has a chemical composition consisting of C: 0.025% to 0.084%, Si: 0.10% to 0.30%, Mn: 0.70% to 1.80%, controlled amounts of P, S, Al, N, and O, Nb: 0.001% to 0.065%, V: 0.001% to 0.065%, Ti: 0.001% to 0.033%, and Ca: 0.0001% to 0.0035% on a mass percent basis and the remainder being Fe and incidental impurities, and satisfies Pcm of 0.20 or less.

A method of manufacturing a filter pipe for vehicles which has an expanded tube portion with a different diameter at one side and is provided with a plurality of through holes formed along a circumferential direction includes: forming the plurality of through holes in a mother member; forming furrows at one end portion of the mother member; forming a planar member having the plurality of through holes and the furrows by a shearing process of the mother member; bending the planar member in a tubular shape and spreading the furrows to form an area where the furrows are formed in an expanded tube shape; and adhering both facing end portions of the planar member so as to form a body having the expanded tube portion at one side thereof.

A forming unit for a profiling machine line, comprising: a plurality of lower rollers (11,12,13) shaped with outer surfaces that envelop, on at least a transversal section plane, a lower curve (P1); a plurality of upper rollers (21,22,23,24,25) profiled with outer surfaces that envelop, on the transversal section plane, an upper curve (P2) substantially parallel to the lower curve (P1).

A method for producing a tube from metal is stated, by use of which method a metal strip by means of a drawing-off installation is moved in the longitudinal direction of said metal strip and is guided through a forming station in which said metal strip is formed to a slot tube having a slot running the in the longitudinal direction. The two edges of the metal strip abut to one another at the slot. Said two ends for producing a fully closed tube are welded to one another by use of a welding installation that is equipped with a laser. The slot tube after leaving the forming station is initially moved into the region of the laser and is then stopped. Thereafter, the regions of the edges of the slot tube that are to be welded to one another are pre-treated by the laser. Thereafter, the power of the laser is set to the welding power thereof that corresponds to the welding temperature, and by switching on the drawing-off installation the slot tube is simultaneously moved in the longitudinal direction of the latter.

A method for producing a tube from metal is stated, by use of which method a metal strip by means of a drawing-off installation is moved in the longitudinal direction of said metal strip and is guided through a forming station in which said metal strip is formed to a slot tube having a slot running the in the longitudinal direction. The two edges of the metal strip abut to one another at the slot. Said two ends for producing a fully closed tube are welded to one another by use of a welding installation that is equipped with a laser. The slot tube after leaving the forming station is initially moved into the region of the laser and is then stopped. Thereafter, the regions of the edges of the slot tube that are to be welded to one another are pre-treated by the laser. Thereafter, the power of the laser is set to the welding power thereof that corresponds to the welding temperature, and by switching on the drawing-off installation the slot tube is simultaneously moved in the longitudinal direction of the latter.

Embodiments of the present disclosure are directed to coiled steel tubes and methods of manufacturing coiled steel tubes. In some embodiments, the final microstructures of the coiled steel tubes across all base metal regions, weld joints, and heat affected zones can be homogeneous. Further, the final microstructure of the coiled steel tube can be a mixture of tempered martensite and bainite.

A steel strip for an electric-resistance-welded steel pipe or tube having a strength of X70 grade or more and excellent HIC resistance and SSC resistance is provided. A steel strip for an electric-resistance-welded steel pipe or tube has a chemical composition containing, in mass %: C: 0.02% to 0.06%; Si: 0.1% to 0.3%; Mn: 0.8% to 1.3%; P: 0.01% or less; S: 0.001% or less; V: 0.04% to 0.07%; Nb: 0.04% to 0.07%; Ti: 0.01% to 0.04%; Cu: 0.1% to 0.3%; Ni: 0.1% to 0.3%; Ca: 0.001% to 0.005%; Al: 0.01% to 0.07%; and N: 0.007% or less, with a balance being Fe and incidental impurities, contents of C, Nb, V, and Ti satisfying the following Expression (1)

[C]−12([Nb]/92.9+[V]/50.9+[Ti]/47.9)≦0.03%  (1),

wherein a ferrite area ratio is 90% or more.