A method for welding austenitic stainless steel sheets, in which welding defects do not easily occur. Austenitic stainless steel sheets each with a sheet thickness of 0.6 to 1.0 mm, which each contain, in terms of mass %, 0.08% or less of C, 1.5 to 4.0% of Si, 2.0% or less of Mn, 0.04% or less of P, 0.01% or less of S, 16.0 to 22.0% of Cr, 10.0 to 14.0% of Ni, and 0.08% or less of N, and contain at least one of Nb and Ti in an amount of 1.0% or less in total, with the rest including Fe and inevitable impurities, are overlapped and the overlapped portion is welded by arc welding. In addition, the back side of a deposited portion is cooled from 1200 C. to 900 C. at a cooling rate of 110 C./sec or higher.

A method for producing a multilayer large pipe having an outer support layer and at least one inner liner layer. Advantages with regard to productivity and the properties of the multilayer large pipe are achieved by the sequence of method steps wherein production of a support sheet is pre-bent to a predetermined initial bending radius for the support layer and at least one liner sheet is pre-bent to a predetermined initial bending radius for the liner layer, placement of the at least one pre-bent liner sheet against the inside of the pre-bent support sheet, with a positioning and parallel alignment of its longitudinal edges extending in the direction of the bending axis in order to form the support layer and the at least one liner layer, there is integral joining of at least one of two longitudinal edges of the at least one liner sheet to the support sheet, shaping of the composite of the integrally joined support layer and at least one liner layer to form a slit multilayer large pipe by a bending machine, with nonpositive, frictional engagement in liner regions that are not integrally joined, and there is closing of the remaining gap of the slit multilayer large pipe with a longitudinal seam by welding.

A metal member includes a first plate, and a second plate abutting against and welded to the first plate in at least one butt portion. In the butt portion, a length from a first end to a second end of a welding boundary line between the first plate and the second plate is longer than a length of a straight line connecting the first end to the second end of the welding boundary line.

A metal member includes a first plate, and a second plate abutting against and welded to the first plate in at least one butt portion. In the butt portion, a length from a first end to a second end of a welding boundary line between the first plate and the second plate is longer than a length of a straight line connecting the first end to the second end of the welding boundary line.

A new technique in welding is provided that utilizes vibration during the welding process. The technique requires a pneumatic control panel having a master pneumatic input and dual pneumatic outputs. Each pneumatic output powers a pneumatic vibrator arranged in a particular orientation with respect to the weldment. The vibrators may be arranged such that the axes of rotation of the vibrators are orthogonal to the vector of the weld seam. The vibrators are set using the pneumatic control panel to vibration frequencies that are out of phase sufficient to form a beat frequency in the weldment. The weld produced when the welding occurs during this vibration yields less distortion and stronger and more predictable welds.

A new technique in welding is provided that utilizes vibration during the welding process. The technique requires a pneumatic control panel having a master pneumatic input and dual pneumatic outputs. Each pneumatic output powers a pneumatic vibrator arranged in a particular orientation with respect to the weldment. The vibrators may be arranged such that the axes of rotation of the vibrators are orthogonal to the vector of the weld seam. The vibrators are set using the pneumatic control panel to vibration frequencies that are out of phase sufficient to form a beat frequency in the weldment. The weld produced when the welding occurs during this vibration yields less distortion and stronger and more predictable welds.

A method of welding surface-treated members together using a welding wire includes a step of transferring a droplet detached from the wire to the members; and a step of pushing the melt pool in the direction opposite to the direction of welding in such a manner that the gas generated from the members during welding is released from the site of generation. The melt pool is pushed to expose the overlapped region of these members. The gas generated from the members is released to the exposed portion, preventing generation of pores such as blowholes, and also generation of spatters.

A method of welding surface-treated members together using a welding wire includes a step of transferring a droplet detached from the wire to the members; and a step of pushing the melt pool in the direction opposite to the direction of welding in such a manner that the gas generated from the members during welding is released from the site of generation. The melt pool is pushed to expose the overlapped region of these members. The gas generated from the members is released to the exposed portion, preventing generation of pores such as blowholes, and also generation of spatters.

A lap-fillet arc welding joint includes a weld bead, the weld bead being formed on an end portion of one sheet of overlapped two sheets and a surface of other sheet along the end portion. The other sheet includes a projecting portion projecting from the surface at a side of a weld toe of at least one of a start portion and a termination portion of the weld bead. The weld toe is located on a slope surface portion of the projecting portion at a side of the end portion of the one sheet.

A lap-fillet arc welding joint includes a weld bead, the weld bead being formed on an end portion of one sheet of overlapped two sheets and a surface of other sheet along the end portion. The other sheet includes a projecting portion projecting from the surface at a side of a weld toe of at least one of a start portion and a termination portion of the weld bead. The weld toe is located on a slope surface portion of the projecting portion at a side of the end portion of the one sheet.