This document provides information on flux cored arc welding (FCAW) and submerged arc welding (SAW). It discusses the concepts of polarity and magnetic fields in welding. It explains the differences between constant current and constant voltage welding machines and their output slopes. It also covers electrode classifications for FCAW and SAW and provides details on applications, advantages, and limitations of each process.

1. FCAW & SAW WELDING
By- Jitendra Bhatia
Date:- 2 Dec 2015

3.  Arc welding is of two types
 Why? DC welding are used for all types of
welding{thick or thin material}
 Why AC welding machines are not .
Arc
welding
AC
welding
DC
welding

4.  Ac welding polarity are not fixed…
 Due to polarity changes we can not use for all types
of welding

5.  Fixed polarity
 With the help of fixed polarity. We can handle
according to use thick or thin welding.

6. WHAT IS CONCEPT BEHIND POLARITY
If work piece is connect with positive terminal and electrode are connected with
negative terminal then this type of polarity..called “straight polarity”

7. REVERSE POLARITY
 If work piece are connected with negative terminal and electrode are
connected with positive terminal then this type of welding we called “Reverse
welding”

8. HOW CAN WORK POLARITY
 When we flow current in electrode and work piece, then due to flow of current a
magnetic field is obtained between electrode and work piece.

9. MAGNETIC FIELD
Then those magnetic field are set up b/w work piece
and electrode .then due to magnetic field are some
deflect in magnetic field direction.
These concept are use in forward and reverse
welding.
When electrode are move in magnetic field direction
.then we called forward welding. Due to this welding
we weld very thick material.
When we move electrode in reverse dirction of
magnetic field.then these type of welding we called
revrse welding .due to this welding we can weld thin
type of material.

10. WELDING POWER SOURCES
 Each type of power source has fundamental electrical differences that best
suit particular processes
 Welding machine
 Must meet changing arc load and environmental conditions instantly
 Must deliver exact amount of electric current precisely at right time to
welding arc
 Available in wide variety of types and sizes

11. WELDING POWER SOURCES
 Also known as power supplies and welding machines
 Two classifications
 Output slope
 constant current
 constant voltage
 Power source type
 Transformer – Will deliver only AC
 Transformer-rectifier – Either AC or DC
 Motor Alternator – AC and DC if equipped with rectifier
 Motor Generator – Only DC

12. TYPE OF OUTPUT SLOPE
 Two basic types
 Constant current
 Referred to as variable voltage power sources
 Constant voltage
 Referred to as constant potential power sources

13. OUTPUT SLOPE
 Relationship between output voltage and output current (amperage) of
machine as current increased or decreased
 Also called volt-ampere characteristic or curve
 Largely determines how much welding current will change for given change in
load voltage
 Permits welding machine to control welding heat and maintain stable arc
 Indicates type and amount of electric current designed to produce
 Each arc welding process has characteristic output slope
 SMAW and GTAW require steep output slope from constant current
welding machine
 GMAW and FCAW require relatively flat output slope from constant
voltage power source
 Submerged arc welding adaptable to either slop

14.  Constant current Power Sources
 Has a static volt-ampere curve that tends to produce a relatively
constant load current
 If arc length varies because of external influences which result is slight
change in arc voltage the welding current remains substantially
constant
 Each current setting yields separate volt-ampere curve
 No-load or Open Circuit voltage of constant current arc welding power
sources is considerably higher than the arc voltage.
 When used in a semi automated or automated application where
constant arc length is required, an arc voltage sensing wire feeder can
be used to maintain constant arc length.

15. CONSTANT CURRENT
WELDING MACHINES
 Used for shielded metal arc welding and gas tungsten arc welding
 Current remains fairly constant regardless of changes in arc length
 Called drooping voltage, variable voltage, or droppers because of the
substantial downward (negative slope) of the curves
 Load voltage decreases as welding current increases
 Constant current welding machines
 Steep output slope
 Available in both d.c. and a.c. welding current
 Steeper the slope, the smaller current change
 Enables welder to control welding current in specific range by changing length
of arc

16. CONSTANT CURRENT
OUTPUT SLOPE
Some jobs require steep volt-ampere curve
Other jobs use less steep
volt-ampere curve

17. CONSTANT VOLTAGE
WELDING MACHINES
 A Constant voltage arc welding power sources is a power source which has
means for adjusting the load voltage and which has a static volt ampere curve
that tends to produce a relatively constant load voltage.

18. TYPICAL OUTPUT SLOPES

19. OPEN CIRCUIT VOLTAGE/ARC VOLTAGE/LOAD VOLTAGE
 OCV is the voltage at the output terminals of a welding power source when it
is energized, but current is not being drawn.
 OCV is one of design factors influencing the performance of all welding power
sources
 Voltage generated by welding machine when no welding being done
 Machine running idle
 Arc voltage
 Voltage generated between electrode and work during welding
 Load voltage
 Voltage at output terminals of welding machine when arc is going
 Combination of arc voltage plus voltage drop in welding circuit

20. OPEN CIRCUIT AND ARC VOLTAGE
 Open circuit voltage runs between 50-100 volts
 Drops to arc voltage when arc struck
 Arc voltages
 Range: 36 volts (long arc) to 18 volts (short arc)
 Determined by arc length held by welder and type of electrode used
 Arc lengthened, arc voltage increases and current decreases

21. OPEN CIRCUIT AND ARC VOLTAGE
 Open circuit voltage on constant current machines higher than on most
constant voltage machines
 Arc voltage depends on physical arc length at point of welding and controlled
by welder
 Shielded metal arc welding
 Gas Tungsten arc welding
 Arc voltage much lower than open circuit voltage

22. FOUR TYPES OF POWER SOURCE
 Engine-driven generators
 Powered by gas or diesel combustion engine
 Can be found with a.c. or d.c. electric motor
 No longer being manufactured and rarely found
 Transformer-rectifiers
 Use basic electrical transformer to step down a.c. line power voltage to
a.c. welding voltage
 Welding voltage then passed through rectifier to convert a.c. output to
d.c. welding current
 May be either d.c. or a.c.-d.c. machines

23. FOUR TYPES OF POWER SOURCE
 A.C. transformers
 Used to step down a.c. line power voltage to a.c. welding voltage
 Inverters
 Increases frequency of incoming primary power
 Constant current, constant voltage, or both
 Produce a.c. or d.c. welding current

24. FLUX CORED ARC WELDING (FCAW)

25. FCAW
 Process uses an arc between continuous filler wire and weld pool.
 Process is used with shielding from a flux contained within the tubular
electrode, with or without shielding from an externally supplied gas, and
without the application of pressure.
 Flux cored electrode is a composite tubular filler metal electrode consisting of
metal sheath and a core of various powdered materials.
 The feature that distinguishes the FCAW process from other arc welding
processes is the enclosure of fluxing ingredients within a continuously fed
electrode.
 Normally a semiautomatic process

26. FCAW
 FCAW process is similar as MIG
 The electrodes, or filler wire, used in FCAW is completely different then MIG
welding. The main difference is that the electrodes have a hollow centre
filled with flux.
 Flux Cored Arc Welding Electrodes Types and Designations
 Flux core arc welding electrodes come in two types:
 1. Self-Shielding – Molten Metal is protected through the decomposition and
vaporization of flux core by the heat of the arc.
 2. Gas-Shielding – Makes use of a protective gas flow in addition of the flux
core action
 Shielding Gas usually Co2 or Mixture of Argon and Co2 (Here we are
using 80% Argon + 20%Co2)

27. FCAW
 Function of Flux same as SMAW Flux Coating
 To Provide Shielding gas through chemical decomposition
 Act As di-oxidisers which will help to purify and produce a sound weld
metal.
 To Form a slag and this will float on the molten weld metal and protect it
from atmosphere during solidification.
 Act as Arc Stabilizers
 Add alloying elements

29. FCAW ELECTRODE CLASSIFICATION
E71 T – 1M
Electrode
Minimum UTS
70,000 psi
Position
Flux Cored /Tubular
Electrode
Type Gas, Usability
and Performance
Flux-Cored Arc Welding
American Welding Society Specification
AWS A5.20 and AWS A5.29.

30.  Flux Cored Arc Welding (FCAW):-
 Current- DC
 Polarity – DCEP
 Current Range 142-185 Amps
 Voltage Range 20-22V
 Electrode wire speed range – 140-155 mm/min
 Size of filler metals – 1.2 mm dia
 Preheat temp – 121 degree C

31.  E - Stands for electrode.
 7 – Identifies the minimum tensile strength of the weld per square inch, and in
this case, you need to add four zeros (70,000). What this means is the filler
metal has a minimum of 70,000 pounds of tensile per square inch of weld.
 1 – Identifies what position the electrode is designed to weld in. There are
only two designations and they are zero and one. Zero means the electrode
can only weld in the flat and horizontal positions. One means it can weld in
any position.
 T – Stands for Tubular and this will be how you know it is a flux cored
electrode. If this were a MIG electrode, it would have an “S”, which stands for
Solid.
 1 – Identifies the type of flux that is inside of the electrode.
 M stands for Low Maganese

33. • Fluxes:-
 Flux gives alloys to bead material
 Bead becomes stronger than even parent material
 Provide heat treatment to the bead
 Protect the bead from attack of atmosphere gases
 Better arc stabilization
 Control the arc weld pool viscosity.

34.  Material Used for electrode coatings:-
 Rutile
 Calcium carbonate or limestone
 Fluorspar or fluorite
 Solka floc
 Felspar
 Ball clay
 Iron powder
 Ferromanganese
 Mica
 Sodium alginate
 Deoxidizing Elements :- Alumina, Graphite
 Slag Formation Component :- Iron oxide, Silicon oxide
 Arc Stabilizers:- Sodium oxide, magnesium oxide, calcium oxide, titanium oxide
 Weld Strength :- Chromium, Tungsten, Nickel, Cobalt, Vanadium

36. APPLICATIONS
 Use to weld carbon and low alloy steels
 Stainless steels
 Cast irons
 It is also used for arc spot welding of lap joints in the sheet and plate, as well as for
cladding and handcrafting.
Flux-Cored Arc Welding

37. ADVANTAGES
 High deposition rates
 Deeper penetration than SMAW
 High-quality
 Less pre-cleaning than GMAW
 Slag covering helps with larger out-of-
position welds
 Self-shielded FCAW is draft tolerant.
 Using small diameter electrode wires,
welding can be done in all positions
 Some flux-cored wires do not need an
external supply of shielding gas, which
simplifies the equipment
 The electrode wire is fed continuously
so there is very little time spent on
changing electrodes.
Flux-Cored Arc Welding

38. LIMITATIONS
 Slag must be removed
 More smoke and fumes than GMAW
and SAW
 Spatter
 FCAW wire is more expensive
 Equipment is more expensive and
complex than for SMAW
Flux-Cored Arc Welding

39. SUBMERGED ARC WELDING

40. SUBMERGED ARC WELDING

41. • Submerged Arc Welding :-
 SAW produces coalescence of metals by heating them with an arc between a
bare metal electrode and the work.
 The arc and molten metal are submerged in a blanket of granular fusible flux on
the work.
 In SAW, the arc is covered by a flux. Flux main roles are :-
 The stability of arc
 Mechanical and chemical properties of the final weld deposit
 Quality of the weld.

42. • Submerged Arc Welding :-
 The submerged arc welding process is similar to the gas metal arc welding
process except the arc is struck under a blanket of granular flux, hence the name
submerged arc welding.
 Continuous bare wires in the form of coils and dry granular fluxes are used in the
combination as consumables for SAW
 The Flux protects the arc, the molten filler metal and hot base metal from oxygen,
nitrogen and water vapor in air.
 The Flux Sprinkles on the work piece ahead of the welding wire and the electrode
ploughs through the flux making the weld.
 Arc being Submerged, there are no heat losses from arc through radiation. This
makes the process highly thermal efficient (nearly 90% of the heat generated in
arc is utilized).
 Current- DC
 Polarity – DCEP
 Voltage- Constant
 Current Range – 390-530 Amps
 Travel Speed– 295-405 mm/min
 Electrode – F7A2-EL8

43. SAW FLUX / FILLER METAL COMPOSITIONS
F7A2-EL8 F indicates a submerged arc welding flux
 7 indicates the tensile strength ( in increments of 10000 psi)
 A indicates condition of heat treatment ( A for as welded and P for post
weld heat treatment)
 2 indicates the temperature in -20°F at which the impact strength of
the weld metal meets or exceeds 20 ft-lbs
 EL8 – Wire
 E – For Electrode
 L – Indicates for Low Manganese
 8 Stands for .08% C

44. ADVANTAGES
 High deposition rates
 Consistent weld quality attributable mechanized
application of process.
 High weld metal recovery due to absence of
spatter losses
 High thermal efficiency
 Reduced welder fatigue due to absence of
irritating arc radiation
 No arc flash or glare
 Minimal smoke and fumes
 Flux and wire added separately - extra
dimension of control
 Easily automated
 Joints can be prepared with narrow grooves
 Can be used to weld carbon steels, low alloy
steels, stainless steels, chromium-molybdenum
steels, nickel base alloys
Submerged Arc Welding

45. LIMITATIONS
 High current associated with the process
limit the application to thickness greater
than 3/16”.
 Flux obstructs view of joint during welding
 Flux is subject to contamination  porosity
 Restricted to the flat position for grooves -
flat and horizontal for fillets
 Slag removal required
 Flux handling equipment
Submerged Arc Welding

46. APPLICATIONS
 Pressure Vessel Fabrication
 Ship and barge building
 railroad car fabrication
 Pipe manufacturing
 Fabrication of structural members where long welds are required.
 SAW is not suitable for all metals and alloys.
 It is widely used on carbon Steels, Low alloy structural steels, and stainless
steels, high carbon Steels and nic
Flux-Cored Arc Welding