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Electro slag Welding
Electro slag Welding is a welding process, in which the heat isgenerated by an electric current passing between the consumableelectrode (filler metal) and the work piece through a molten slagcovering the weld surface.
Prior to welding the gap between the two work pieces is filledwith a welding flux. Electro slag Welding is initiated by an arcbetween the electrode and the work piece (or starting plate).Heat, generated by the arc, melts the fluxing powder and formsmolten slag. The slag, having low electric conductivity, ismaintained in liquid state due to heat produced by the electriccurrent.
Electro slag Welding
Electro slag Welding is a welding process, in which the heat isgenerated by an electric current passing between the consumableelectrode (filler metal) and the work piece through a molten slagcovering the weld surface.
Prior to welding the gap between the two work pieces is filledwith a welding flux. Electro slag Welding is initiated by an arcbetween the electrode and the work piece (or starting plate).Heat, generated by the arc, melts the fluxing powder and formsmolten slag. The slag, having low electric conductivity, ismaintained in liquid state due to heat produced by the electriccurrent.
Electro slag welding (ESW) is a highly productive, single pass weldingprocess for thick (greater than 50 mm) materials in a vertical or close tovertical position. An electric arc is initially struck by wire that is fed intothe desired weld location and then flux is added
The slag reaches a temperature of about 3500°F (1930°C). Thistemperature is sufficient for melting the consumable electrode and workpiece edges. Metal droplets fall to the weld pool and join the work pieces.
Electro slag Welding is used mainly for steels.
Electro slag welding (ESW) is a highly productive, single pass weldingprocess for thick (greater than 50 mm) materials in a vertical or close tovertical position. An electric arc is initially struck by wire that is fed intothe desired weld location and then flux is added
The slag reaches a temperature of about 3500°F (1930°C). Thistemperature is sufficient for melting the consumable electrode and workpiece edges. Metal droplets fall to the weld pool and join the work pieces.
Electro slag Welding is used mainly for steels.
Electroslag Welding equipments
Power sourceWire feederElectrode guide tubeRetaining BlocksWelding head and Controls
Power sourceWire feederElectrode guide tubeRetaining BlocksWelding head and Controls
Power source
100 % duty cycle
AC and DC (EP) power source
10,000 Amp
OCV 60V (range is 30 V to 100 V)
Remote controlled
100 % duty cycle
AC and DC (EP) power source
10,000 Amp
OCV 60V (range is 30 V to 100 V)
Remote controlled
Wire feeder
Feed roller
Drive motor
Provide oscillationrack and pinion motioncam and crank arrangement
Feed roller
Drive motor
Provide oscillationrack and pinion motioncam and crank arrangement
Retaining Blocks
Maintain the slag and molten metal with in the cavity
Solid copper and water cooled copper shoe
Travel upward as welding progress
For low melting point graphite or steel can be used
Maintain the slag and molten metal with in the cavity
Solid copper and water cooled copper shoe
Travel upward as welding progress
For low melting point graphite or steel can be used
Welding head and Controls
It Consists :-
wire feeder
Electrode supply
Wire guide tube
Oscillation drive
It Consists :-
wire feeder
Electrode supply
Wire guide tube
Oscillation drive
Consumables
Electrode
Solid and metal-cored
Wire range 1.6 to 4.0 mm diameter.
Electrode
Solid and metal-cored
Wire range 1.6 to 4.0 mm diameter.
Flux
Should sufficient resistance to melt the filler material.
Optimum viscosity.
Melting point should lower then the material to be joined.
5 to 10 Kg for each 100kg of metal deposited.
Two types of fluxesstarting (low melting point, )running
Should sufficient resistance to melt the filler material.
Optimum viscosity.
Melting point should lower then the material to be joined.
5 to 10 Kg for each 100kg of metal deposited.
Two types of fluxesstarting (low melting point, )running
ESW variables Welding Current Welding Voltage Electrode diameter Electrode extension Electrode oscillation Slag Pool depth Number of electrode and their spacing Root gap
Welding Current Welding Voltage Electrode diameter Electrode extension Electrode oscillation Slag Pool depth Number of electrode and their spacing Root gap
Welding current
It depend upon welding voltage and Electrode feed rate. Increases with increase in wire feed rate. Increasing in current means increasing in welding speed. Due to increase in welding speed depth of penetration will
reduce and lack of fusion is likely occur. It may cause cracking Max level of current used bellow 500 A for wire dia 3.2 mm
and bellow 400 A for 2.4 dia.
It depend upon welding voltage and Electrode feed rate. Increases with increase in wire feed rate. Increasing in current means increasing in welding speed. Due to increase in welding speed depth of penetration will
reduce and lack of fusion is likely occur. It may cause cracking Max level of current used bellow 500 A for wire dia 3.2 mm
and bellow 400 A for 2.4 dia.
Welding voltage
Effect the depth of penetration and stability of process. Excessive voltage may cause overheating of metal,
gassing of slag pool and even sparking. With Low voltage electrode may short-circuit to the
pool of molten metal. Selection of voltage is governed by the type of flux
used and is usually 32 to 55 volt per electrode. Higher voltage is used with thicker section.
Effect the depth of penetration and stability of process. Excessive voltage may cause overheating of metal,
gassing of slag pool and even sparking. With Low voltage electrode may short-circuit to the
pool of molten metal. Selection of voltage is governed by the type of flux
used and is usually 32 to 55 volt per electrode. Higher voltage is used with thicker section.
Electrode diameter
Greater the diameter of electrode more the depth ofpenetration and the suitable operation of process. In such cases use is made of electrode plates instead of
large diameter wires.
Greater the diameter of electrode more the depth ofpenetration and the suitable operation of process. In such cases use is made of electrode plates instead of
large diameter wires.
Electrode Extension Distance between contact tube and slag pool surface is
referred to as “dry electrode extension”. And length ofelectrode dipped in slag is called “wet extension”. Electrode extension of 50-75mm are normally used. Bellow 50 mm resulting in overheating of contact tube
and more then 75 mm resulting in overheating ofelectrode because of increasing in electrode resistance. Leads to melt the electrode at the surface of slag pool
instead of inside it.
Distance between contact tube and slag pool surface isreferred to as “dry electrode extension”. And length ofelectrode dipped in slag is called “wet extension”. Electrode extension of 50-75mm are normally used. Bellow 50 mm resulting in overheating of contact tube
and more then 75 mm resulting in overheating ofelectrode because of increasing in electrode resistance. Leads to melt the electrode at the surface of slag pool
instead of inside it.
Electrode Oscillation
Plates upto 75 mm thick can be welded withoutoscillation but with high voltage. To achieve better fusion it is necessary to oscillate the
electrode horizontally across the thickness. Oscillation speed normally varies between 10-40
mm/sec. Increasing in speed result in reduce weld width.
Plates upto 75 mm thick can be welded withoutoscillation but with high voltage. To achieve better fusion it is necessary to oscillate the
electrode horizontally across the thickness. Oscillation speed normally varies between 10-40
mm/sec. Increasing in speed result in reduce weld width.
Slag Pool depth
Excessive pool depth resulting slag inclusion. Lead to reduce weld penetration. Too shallow result arcing on the slag surface. Optimum depth of weld pool is about 40 mm And the range can be used between 25 mm to 60 mm.
Excessive pool depth resulting slag inclusion. Lead to reduce weld penetration. Too shallow result arcing on the slag surface. Optimum depth of weld pool is about 40 mm And the range can be used between 25 mm to 60 mm.
Root gap
It effect the depth of penetration Decrease in root gap result in decrease in penetration
and vice-versa. Narrow gap increase in short-circuit. Large gap required an extra amount of filler metal. Feasible root gap should between 20-35 mm.
It effect the depth of penetration Decrease in root gap result in decrease in penetration
and vice-versa. Narrow gap increase in short-circuit. Large gap required an extra amount of filler metal. Feasible root gap should between 20-35 mm.
Applications of ESW
Welding of structure, machinery, ships, pressure vesseland casting. Applicable to long butt weld.
Welding of structure, machinery, ships, pressure vesseland casting. Applicable to long butt weld.
Advantages of Electroslag Welding:
High deposition rate - up to 45 lbs/h (20 kg/h); Low slag consumption (about 5% of the deposited
metal weight); Low distortion; Unlimited thickness of work piece.
Disadvantages of Electroslag welding:
Coarse grain structure of the weld; Low toughness of the weld; Only vertical position is possible.
Advantages of Electroslag Welding:
High deposition rate - up to 45 lbs/h (20 kg/h); Low slag consumption (about 5% of the deposited
metal weight); Low distortion; Unlimited thickness of work piece.
Disadvantages of Electroslag welding:
Coarse grain structure of the weld; Low toughness of the weld; Only vertical position is possible.
Variants of ESW
Consumable guide ESW ESW with plate electrode Electroslag butt welding
Consumable guide ESW ESW with plate electrode Electroslag butt welding
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