Produced background Petrochemical industry hydrogenation reactor, the original flow tower, coal liquefaction reactors and nuclear power plant thick-walled pressure vessels and other internal surfaces are required large-area surfacing high temperature resistant, anti-oxidation and hydrogen sulfide corrosion stainless steel lining. In the 1970s, a great deal of submerged arc surfacing (SAW) technology was widely used in this field at home and abroad. With a very narrow width from the narrow to 60mm, 90mom, 120mm, 150mm broadband direction. The technology in the dilution rate and deposition rate than the submerged arc welding has made great strides, but with the increasing size of the pressure vessel, high parameterization, and promote surfacing technology to a higher quality and more efficient direction. In the early 1970s, Germany first invented, and later by Japan, the United States, the former Soviet Union and other countries to further improve the strip with electroslag welding technology because it has more than submerged arc welding with higher production efficiency, lower dilution and Good weld forming advantages, in recent years at home and abroad have been rapid development and more common applications.
Electrode with slag welding characteristics
Compared with strip submerged arc welding, ESW has the following characteristics:
(1) The deposition rate increased by 60% -80%.
(2) Due to the very shallow penetration (about 10% to 15% dilution), only half is diluted into the base metal.
(3) Low welding voltage (24-26 V).
(4) current and current density (60 rain wide through the current of 1000-1 250A ribbon, the corresponding current density of 33-42 A / mm2), especially high-speed flux allows the welding current exceeds 2000A, the corresponding current density 70 A / ram2.
(5) Increased welding speed (50% -200%), resulting in increased coverage.
(6) The heat input is roughly the same.
(7) low loss of flux (about 0.4-0.5 kg / kg).
(8) ESW weld metal curing rate is very low, is conducive to stomatal escape, reduce stomatal defects. Oxygen can escape from the molten electroslag pool to the surface; the surfacing metal surface is relatively clean, reducing the tendency of hot cracking and intergranular corrosion from a metallurgical point of view. In practical application of industrial production, the weld surface of the product relative to the base metal, with a higher deposition rate and a lower dilution rate is very important. Submerged arc surfacing has been widely used in the surfacing of large area of the surface, but the ESR surfacing technology is gradually dominated.
Post time: Jan-15-2018