A system and method of welding or additive manufacturing is provided where at least two welding electrodes are provided to and passed through a two separate orifices on a single contact tip and a welding waveform is provided to the electrodes through the contact tip to weld simultaneously with both electrodes, where a bridge droplet is formed between the electrodes and then transferred to the puddle.

A submerged arc welded joint having a weld metal formed by performing submerged arc welding with a heat input of 300 kJ/cm or more. The joint has a weld metal having a specified chemical composition, specified yield strength, and specified tensile strength. The weld metal has a specified absorbed energy vE0, as measured by a V-notch Charpy impact test performed at a testing temperature of 0? C. Ceq is in a range of 0.65 to 1.00, and a is 6.0 or less, as expressed by the equations below.

Ceq=[C]+0.17[Mn]+0.04[Si]+0.025[Ni]+0.2[Cr]+0.25[Mo](1)

?=30[C]+0.7[Mn]+[Ni]?([Si]+0.5[Cr]+1.5[Mo])(2)

Here, in the equation (1) and the equation (2), the expression [element symbol] denotes a content (mass %) of the corresponding element in the weld metal described above.

A submerged arc welded joint having a weld metal formed by performing submerged arc welding with a heat input of 300 kJ/cm or more. The joint has a weld metal having a specified chemical composition, specified yield strength, and specified tensile strength. The weld metal has a specified absorbed energy vE0, as measured by a V-notch Charpy impact test performed at a testing temperature of 0? C. Ceq is in a range of 0.65 to 1.00, and a is 6.0 or less, as expressed by the equations below.

Ceq=[C]+0.17[Mn]+0.04[Si]+0.025[Ni]+0.2[Cr]+0.25[Mo](1)

?=30[C]+0.7[Mn]+[Ni]?([Si]+0.5[Cr]+1.5[Mo])(2)

Here, in the equation (1) and the equation (2), the expression [element symbol] denotes a content (mass %) of the corresponding element in the weld metal described above.

A weld joint with an excellent CTOD property is produced with a weld metal, using a steel plate as a base metal. The steel plate has a chemical composition including C: 0.03% to 0.09%, Si: 0.01% to 0.35%, Mn: 1.3% to 2.0%, P: 0.012% or less, S: 0.0035% or less, Al: 0.01% to 0.06%, Ni: less than 0.3%, Mo: less than 0.10%, Nb: 0.005% to 0.023%, Ti: 0.005% to 0.025%, B: less than 0.0003%, N: 0.002% to 0.005%, Ca: 0.0005% to 0.0050%, and O: 0.0030% or less, with the components additionally satisfying a predetermined relationship. The weld metal has a chemical composition including C: 0.040% to 0.090%, Si: 0.1% to 0.8%, Mn: 1.0% to 2.5%, Al: 0.020% or less, Ni: 0.1% to 1.0%, Mo: 0.05% to 0.50%, Ti: 0.005% to 0.050%, and B: 0.0015% or less, the balance being Fe and incidental impurities.

A weld joint with an excellent CTOD property is produced with a weld metal, using a steel plate as a base metal. The steel plate has a chemical composition including C: 0.03% to 0.09%, Si: 0.01% to 0.35%, Mn: 1.3% to 2.0%, P: 0.012% or less, S: 0.0035% or less, Al: 0.01% to 0.06%, Ni: less than 0.3%, Mo: less than 0.10%, Nb: 0.005% to 0.023%, Ti: 0.005% to 0.025%, B: less than 0.0003%, N: 0.002% to 0.005%, Ca: 0.0005% to 0.0050%, and O: 0.0030% or less, with the components additionally satisfying a predetermined relationship. The weld metal has a chemical composition including C: 0.040% to 0.090%, Si: 0.1% to 0.8%, Mn: 1.0% to 2.5%, Al: 0.020% or less, Ni: 0.1% to 1.0%, Mo: 0.05% to 0.50%, Ti: 0.005% to 0.050%, and B: 0.0015% or less, the balance being Fe and incidental impurities.

There is provided a welding structure member excellent in corrosion resistance in an environment where high-concentration sulfuric acid condenses, the welding structure member including base material having a chemical composition containing, in mass percent, C0.05%, Si1.0%, Mn2.0%, P0.04%, S0.01%, Ni: 12.0 to 27.0%, Cr: 15.0% or more to less than 20.0%, Cu: more than 3 0% to 8.0% or less, Mo: more than 2.0% to 5.0% or less, Nb1.0%, Ti0.5%, Co0.5%, Sn0.1%, W5.0%, Zr1.0%, Al0.5%, N<0.05%, Ca0.01%, B0.01%, and REM0.01%, with the balance: Fe and unavoidable impurities, and the welding structure member including including weld metal having a chemical composition containing, in mass percent, C0.10%, Si0.50%, Mn3.5%, P0.03%, S0.03%, Cu0.50%, Ni: 51.0 to 69.0%, Cr: 14.5 to 23.0%, Mo: 6.0 to 17.0%, Al0.40%, Ti+Nb+Ta4.90%, Co2.5%, V0.35%, and W4.5%, with the balance: Fe and unavoidable impurities.

Provided is a flux for submerged arc welding that has good welding workability and can reduce the diffusion hydrogen content in a weld metal using either an AC or a DC welding power source. The flux includes Al.sub.2O.sub.3: 15 to 35% by mass; SiO.sub.2: 10 to 30% by mass; MgO: 10 to 25% by mass; F expressed in terms of CaF.sub.2: 10 to 25% by mass; Mn expressed in terms of MnO: 3 to 20% by mass; Na expressed in terms of Na.sub.2O and/or K expressed in terms of K.sub.2O: 0.5 to 4.5% by mass in total; Fe expressed in terms of FeO: 0.5 to 8% by mass; and CaO: 6% by mass or less. A water-soluble SiO.sub.2 in the flux is less than 1% by mass. In addition, the flux has a composition that satisfies the following formula: 0.2[Mg/O]/([Al.sub.2O.sub.3]+[MnO])0.8.

In the case of a method for the heat treatment of erected, preferably large-area tube wall regions or tube wall segments, in particular of a diaphragm wall, of a steam generator, in particular of a power plant, in the installed state, it is sought to provide a solution which permits the use of steel types which are more problematic with regard to power plant operation with elevated steam parameters, in particular the steels T23 and T24, in the erection of steam generators. This is achieved in that the tube wall regions or tube wall segments for heat treatment are subjected, in the installed state in the steam generator, and in particular over a large area, to a stress-relief annealing process.

A multi-electrode submerged arc welding method enables, in multi-electrode submerged arc welding using five or six electrodes, a deep penetration and a large amount of deposit metal to be obtained by supplying a large current, and enables stable arc to be generated by respective electrodes by suppressing magnetic interference. Welding defects can be prevented, beads with a good shape or appearance can be obtained, and the welding speed can be increased.

A multi-electrode submerged arc welding method enables, in multi-electrode submerged arc welding using five or six electrodes, a deep penetration and a large amount of deposit metal to be obtained by supplying a large current, and enables stable arc to be generated by respective electrodes by suppressing magnetic interference. Welding defects can be prevented, beads with a good shape or appearance can be obtained, and the welding speed can be increased.