Abstract: An electric resistance welding operation management device manages a welding operation during manufacture of electric resistance welded steel pipe, in which heat is input to a steel plate, that is being conveyed along a specific conveyance direction and formed into a circular tube shape while pressing side faces of the metal plate with a pair of squeeze rolls, to weld together two circumferential direction edge portions of the metal plate converging in a V-shape. The electric resistance welding operation management device includes an image input section that inputs plural images and each including a Vee convergence region of the steel plate. The electric resistance welding operation management device includes a welding point position derivation section that derives the position of a welding point.

Abstract: An operation management device performs an operation management for electric resistance welding in which a strip-shaped metal plate is formed to have a cylindrical shape in such a manner that both end portions of the metal plate gradually face each other while the metal plate is conveyed, and a Vee convergence section, which is a portion at which both of the end portions butt against each other while facing each other, is welded.

Abstract: The present invention provides a method of production of electric resistance welded steel pipe able to stably reduce weld defects due to oxides by firing plasma and furthermore able to reduce plasma jet noise and comprises shaping steel plate 1 into a tube and electric resistance welding the abutting end faces 4 during which blowing on at least the abutting end faces 4a in the region 6 at the welding upstream side from the weld point 9 where the temperature becomes 650° C. or more a reducing high temperature (pseudo) laminar plasma obtained by applying voltage to a reducing gas containing H2 gas: 2 to 50 vol % to which is added a balance of Ar gas alone or a mixed gas of Ar gas to which N2 gas, He gas, or both are added. At that time, it is preferable to make the applied voltage over 120V and the make the plasma blowing conditions satisfy the following formula (1).

Abstract: An electric resistance welding operation management device 100 manages a welding operation during manufacture of electric resistance welded steel pipe, in which heat is input to a steel plate 1, that is being conveyed along a specific conveyance direction and formed into a circular tube shape while pressing side faces of the metal plate 1 with a pair of squeeze rolls 2a, 2b, to weld together two circumferential direction edge portions 11a, 11b of the metal plate 1 converging in a V-shape. The electric resistance welding operation management device 100 includes an image input means that inputs plural images, successively captured over 3 sec and each including a Vee convergence region of the steel plate 1.

Abstract: An operation management device performs an operation management for electric resistance welding in which a strip-shaped metal plate is formed to have a cylindrical shape in such a manner that both end portions of the metal plate gradually face each other while the metal plate is conveyed, and a Vee convergence section, which is a portion at which both of the end portions butt against each other while facing each other, is welded.

Abstract: Disclosed are a weld joint and a stainless steel-based weld metal composition for the weld joint. The composition and weld joint made therefrom are suitable for welding a zinc-based alloy coated steel sheet. The weld is excellent in corrosion resistance and liquid-metal embrittlement crack resistance. This is accomplished by inhibiting liquid-metal embrittlement cracks of the stainless-steel-based weld metal when the zinc-based alloy coating steel sheet is welded using the stainless-steel-based weld metal. The weld joint comprises a welded portion of weld metal made of stainless-steel-based components, the weld metal containing in mass percent (%): C: 0.01-0.1; Si: 0.1-1; Mn: 0.5-2.5; Ni: 5-11; and Cr: 17-25, and the balance being iron and residual impurities, wherein the following expression are met: ?0.81×Cr equivalent+23.2?Ni equivalent?0.95×Cr equivalent?8.1 . . . (1); Ni equivalent=Ni+30×C+0.5×Mn+30×N . . . (2); Cr equivalent=Cr+Mo+1.5×Si . . . (3).

Abstract: The present invention provides a method of production of electric resistance welded steel pipe able to stably reduce weld defects due to oxides by firing plasma and furthermore able to reduce plasma jet noise and comprises shaping steel plate 1 into a tube and electric resistance welding the abutting end faces 4 during which blowing on at least the abutting end faces 4a in the region 6 at the welding upstream side from the weld point 9 where the temperature becomes 650° C. or more a reducing high temperature (pseudo) laminar plasma obtained by applying voltage to a reducing gas containing H2 gas: 2 to 50 vol % to which is added a balance of Ar gas alone or a mixed gas of Ar gas to which N2 gas, He gas, or both are added. At that time, it is preferable to make the applied voltage over 120V and the make the plasma blowing conditions satisfy the following formula (1).

Abstract: Disclosed are a weld joint and a stainless steel-based weld metal composition for the weld joint. The composition and weld joint made therefrom are suitable for welding a zinc-based alloy coated steel sheet. The weld is excellent in corrosion resistance and liquid-metal embrittlement crack resistance. This is accomplished by inhibiting liquid-metal embrittlement cracks of the stainless-steel-based weld metal when the zinc-based alloy coating steel sheet is welded using the stainless-steel-based weld metal. The weld joint comprises a welded portion of weld metal made of stainless-steel-based components, the weld metal containing in mass percent (%): C: 0.01-0.1; Si: 0.1-1; Mn: 0.5-2.5; Ni: 5-11; and Cr: 17-25, and the balance being iron and residual impurities, wherein the following expression are met: ?0.81×Cr equivalent+23.2?Ni equivalent?0.95×Cr equivalent?8.1 . . . (1); Ni equivalent=Ni+30×C+0.5×Mn+30×N . . . (2); Cr equivalent=Cr+Mo+1.5×Si . . . (3).

Abstract: A martensitic heat-resisting steel comprises, in terms of % by mass, 0.01 to 0.30% of C, 0.02 of 0.80% of Si, 0.20 to 1.00% of Mn, 5.00 to 18.00% of Cr, 0.005 to 1.00% of Mo, 0.20 to 3.50% of W, 0.02 to 1.00% of V, 0.01 to 0.50% of Nb, 0.01 to 0.25% of N, and at least one element selected from the group consisting of Ti, Zr, Ta and Hf in an amount of 0.005 to 2.0% for each of the elements, the volume of (Ti %+Zr %+Ta %+Hf %) in the metal component M of M.sub.23 C.sub.6 type carbides therein being from 5 to 65%. The heat-resisting steel is produced by a process comprising the steps ofadding Ti, Zr, Ta and Hf to a molten steel having chemical components as mentioned above, during the period from 10 minutes before completion of refining to completion of refining, casting said molten steel, working the resulting casting, solution treating said worked product, subjecting said worked product to temporary cooling stop at a temperature from 950.degree. to 1,000.degree. C.

Abstract: A method of manufacturing tubes filled with powdery and/or granular substances, such as flux-cored welding wires. A tube filled with a powdery and/or granular substance is continuously manufactured by forming a metal strip being fed in its longitudinal direction into an unwelded tube (1a) using forming rolls (2), feeding a powdery and/or granular substance (F) into the unwelded tube (1a) being formed through its opening, butt-welding together fringing edges of the opening, and reducing the diameter of the welded tube (1b). An allowable minimum heat input below which cold cracking occurs and a maximum allowable heat input above which spatters whose diameter is not smaller than 0.83 times the inside diameter of the finished tube are generated are determined in advance, and the butt welding is performed with a heat input larger than the allowable minimum heat input and smaller than the allowable maximum heat input.

Abstract: A high-frequency electric resistance welding method combined with the irradiation of a laser beam in which a workpiece is continuously fed and opposed edges of the workpiece are formed into a wedge shape by causing them to converge as they are butted against each other, and the butted edges are melted by heating them with high-frequency resistance heating and a laser beam, to weld the butted edges. The laser beam is projected against the range of over 30% and below 80% of the thickness of the butted edges including the central portion of the thickness to melt the butted edges by the combined heating action of the laser beam and high-frequency current. The corners are heated and melted by means of high-frequency electric resistance heating, so that the butted edges of the workpiece can be melted uniformly through the entire range of thickness.