The author: Release time : 2017-01-04 17:49:44 1521time to browse
Introduction to the
With electroslag surfacing is in extremely developed on the basis of submerged arc welding, a higher deposition efficiency. With electroslag surfacing is it USES conductive slag resistance of hot melt welding material and belt.
The working principle of
Fluent with electroslag welding is controlled electric liquid slag resistance attack by heat as a heat source, welding electrodes, welding wire or plate) and weldment
The principle diagram of the electroslag welding
Composition of surfacing welding layer after melting, cooling process. The head between the plate and comments at the bottom of the arc ignition, holding arc heat melting flux of slag pool, arc burning, the heat source of cheap by arc transition to slag resistance hot. Because of melting metal density, sinking of liquid metal molten pool, slag density is small, below the float in molten pool, the slag pool cover in the metal molten pool, and protect the metal molten pool from the atmosphere purification. Follow an inexhaustible ablation electrodes, liquid metal in the molten pool and the slag are rising up, far from the heat source is the lower part of the liquid metal, forming in the cooling water jacket of the condensed into hardfacing layer under forced cooling. Electroslag slot in the heat generated by the melt into the electroslag groove of the base metal and weld zone, electroslag welding principle and compared with a submerged arc welding, the molten electroslag good thermal conductivity avoids the arc spraying. Flux composition on thermal conductivity, viscosity and curing are affected. In order to improve the big electricity flow deposition layer thickness, the flux basicity and fluoride content is usually very high, make it has high conductivity and lower viscosity. Electroslag tank temperature about 300 ℃ for 2, formed a thin layer of conductive liquid slag, and thermal radiation. Because a lot of heat accumulation, USES the water cooling is necessary to clamp. Because the current is very big, so the ESW welding head than with a submerged arc welding head weighs a lot. With electroslag welding features editor
Compared with a submerged arc welding, ESW has the following features:
(1) the deposition rate increased by 60% to 60%.
(2) due to the shallow depth of molten a 15% dilution rate (about 10%), only half dilution to the parent metal.
(3) low welding voltage (24-26 V).
Deposition rate
(4) current and current density (60 rain wide welding ribbon through current is 250 A, 000-1 l corresponding current density for 33-42 A/was), especially high flux allows the welding current is more than 2, 000 A, current density of 70 A/ram2 accordingly.
(5) improve the welding speed (50% 200%), lead to cover.
(6) thermal input the same.
(7) low flux loss (about 0.4 0.5 kg/kg).
(8) ESW weld metal solidification rate is very low, is beneficial to porosity evolution, reduce the blowhole defects. Oxygen can escape from the molten electroslag pool to the surface; Surfacing welding layer metal surface is clean, from the perspective of the metallurgy reduce the hot crack and corrosion tendency. Industrial production in the practical application, the product of the weld metal surface relative matrix, has high deposition rate and low dilution rate is very important. With a submerged arc welding has been widely used in surface surfacing large area, but the electroslag surfacing technology is gradually dominate. [2]
The process parameters to edit
Adopt reasonable welding technology parameter is stabilize electroslag welding process, welding quality good. Impact with electroslag welding quality of the process parameters of the main welding voltage, current and welding speed, followed by stem elongation, flux layer thickness, amount of overlap between the weld bead and welding position, etc.
(1) the precise control of welding voltage is of great significance to take extremely electroslag welding, when the voltage is too low, has a tendency to take extremely adhesion of parent metal. Obviously increase the voltage is too high, the arc phenomenon and molten pool is not stable, splashes also increases, recommended by the welding voltage is between 20 ~ 30 v.
(2) with a welding current on electroslag surfacing welding quality impact is bigger also. Welding current is added, the weld penetration, weld width and tall, with the increase and dilution rate fell slightly, but too much electricity, splash will increase. Different width of the belt should choose different welding current, such as the phi with a 75 mm x 0.4 mm, current optimization between 1000 ~ 1000 a.
(3) with the increase of welding speed, welding the weld width, and tall, penetration and dilution rate increase, the welding speed is too high, will be an increased incidence of arc, to control the dilution rate, guarantee the welding layer properties, welding speed general control in 15 ~ 425 px/min.
(4) level with electroslag surfacing welding, the base Angle affects the dilution ratio and weld forming, generally recommend using level or slightly sloping (DHS 1 ~ 2 DHS) It is advisable to the uphill welding.
5. Recommended values of other parameters are as follows: with extended length of 25 ~ 35 mm, the thickness of the flux 25 ~ 35 mm, 5 ~ l0mm bead lap. [4]
With electroslag surfacing welding flux editor
Stability of the process of electroslag another necessary condition that the electrical conductivity of the flux must be a good. General electric slag welding flux of conductivity should be 2 ~
With electroslag surfacing welding flux
3 Ω - 25 px 1, 4 ~ 5 times of the ordinary submerged arc welding flux. Using electric slag flux at home and abroad are sintered. The size of the conductivity of flux, depends on the flux composition in chloride (NaF, CaF2, Na3AIF6, etc.) of how many, when the chloride (mass fraction) of less than 40%, for the arc welding process, the scope of 40% ~ 50% is roughly arc, electroslag joint process; After the chloride is more than 50%, can form the whole electroslag process. CaF2 is both a good conductive material and main fluxing agent, therefore CaF2 is usually the main components of the electroslag welding flux. [5]
In addition to the electrical conductivity, flux still need to have good welding technology (deslagging, forming, wettability) and good metallurgical characteristics (small alloying elements loss, less adverse element incremental), appropriate particle size (general than submerged arc welding flux fine granularity). Meet the above requirements, has been used in the production of flux is a lot of more phyletic, if there is any foreign FJ - 1 (Japan), EST122 (Germany), Sandvik37S (United States); Homebred SJ15, SHD202 and so on.
ESAB company [3], for example, production of OKFlux 10.10 to 60 * 0.5 mm welding with welding current can be up to 1800 a, OK Flux used for 60 * 0.5 10.14 mm welding with welding current can be up to 2300 a, suitable for welding of austenitic stainless steel. OK Flux 10.11 especially suitable for welding of nickel base alloy. OK Flux 10.12 especially suitable for small diameter cylindrical surface surfacing. [1] [4]
Magnetic control device
For broadband extremely (with width greater than 60 mm) electroslag surfacing, due to shrinkage of magnetic effect of surfacing welding layer causes bite edge, as with a width increases, increase welding current, bite edge phenomenon is heavier, so must be used to prevent biting edge on the method of magnetic field to produce (magnetic control method). Must be reasonable decorate pole position at the same time, choose the reasonable size, excitation current and magnetic field is too strong or too weak affects the forming of welding bead. Two poles of the magnetic control current can be adjusted respectively. For example the preheating of the flat position of the workpiece, when the belt is 60 mm x 0.5 mm, magnetic control device of the south, the North Pole control current of 1.5 A and 3.5 A respectively; For 90 mm x 0.5 mm with A 3 A and 3.5 A respectively.
