11.3.5 Type of consumable electrode
Three Generic Types of flux covering for MMA that are usually used for (C, C-Mn Steels)
Rutile & High Recovery Rutile
Baking
AWS5.1
designation
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No Backing Needed
E6012  DC
E6013  AC
E6014
Composition
 Titanium Oxide (TiO2) (Rutile sand) (Titania).
 Coatings often colored.
Coating
Characteristics
 Low deposition rates but can be made high if iron
powder added.
Basic
Cellulosic
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Baking Needed
E7015
E7016
E7018
Calcium Compounds as;
 Calcium Carbonate (CaCO3) (Limestone).
 Calcium fluoride (CaF2) (Fluorspar).
 More fluid and fast freezing slag coating than rutile coatings
 No Backing Needed
 X
 Reasonably good mechanical properties.
Resulting weld
Quality
 X
 Moderate welding properties.
 Low strength.
 Low toughness.
 High weld quality
 Good mechanical properties
 Good strength due to Low hydrogen potential gives weld metal.
 Good toughness.
Weld Profile
 Smooth weld profiles produced by the viscous slag.
Advantages
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 Poor weld profile.
 Convex and coarse surface.
 Used to control hydrogen contents in the weld
Low control “Easy to use”
Low cost
Easy arc ignition.
Smooth arc operation.
 Need some moisture to give gas shield.
Disadvantages.
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 E6010  DC
 E6011  AC
 Cellulose ((C6H10O5) n)
 Industrially extracted cellulose or wood flour
 Low deposition rates (Deposition efficiency “Recovery”)
 Rough weld profile.
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High cost.
High welder skill required.
Poor stop/start properties.
Requires high welding currents/speeds
Low control “Easy to use”.
Rapid burn-off rate giving (rate of electrode melting)
Deep penetration in all positions.
High welding speeds without the risk of lack of fusion.
Weld deposit can be coarse and with the fluid slag
Characteristic Smell welding
Large volumes of shielding gas
Produce a gas shield high in hydrogen raising the arc
voltage.
 High crack tendency.
 Higher spatter levels.
Spatter
 Low spatter Levels.
Hydrogen
content
 High Hydrogen content.
 Hydrogen content is 25-30 ml/100g of weld
metal.
 They cannot be made with a low hydrogen
content.
 Low hydrogen weld metal,
 It have the lowest level of hydrogen (less than 5ml/100g of weld
metal).
 Low crack tendency.
 Too High Hydrogen content.
 Hydrogen content is 80-90 ml/100g of weld metal.
 Risk of cracking (need to keep joint hot during welding to
allow H to escape).
Slag removal
 Easily removable slag due to smooth profile.
Positions
 All positions but Many are designed for flat position
 Horizontal vertical H/V positions
 Positional welding possible with fluid slag containing
Fluoride.
 Difficult slag removal
 Deslagging requires more effort than for other types.
 Being a fast freezing assists welding in the vertical and overhead positions
 Difficult slag removal
 remains Thin and Friable with coarse weld profile
 All positions
 Suitable for vertical-down welding.
Applications
 Low strength, thin steel. ”General Purpose”
 Cannot be used on high strength steels or thick joints
- cracking risk too high.
 Low pressure pipework, support and brackets.
 Fillet joints.
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Materials to weld
 Used for Ferritic and austenitic steels.
 Used for Ferritic Stainless steels, Ni and CU
 Not suitable for higher strength steels - cracking risk too
high (may not be allowed for Grades stronger than X70).
 XX
 XX
 Not suitable for very thick sections (may not be used on
thicknesses > ~ 35mm).
 Pipes root run overlaying
 Stovepipe Technique.
 Not suitable when low temperature toughness is required
(impact toughness satisfactory down to ~ -20°C).
 Only used on C- and C-Mn Steels.
Shielding gas
 Mainly CO2
 Mainly CO2
 Hydrogen + CO2
 Plastic foil sealed cardboard box
 Plastic foil sealed cardboard box
High strength steels.
XX
XX
Very suitable for high pressure work.
These electrodes are used for welding medium and heavy thick section
fabrications where
 Resistance to cracking due to high restrain are required
 Vacuum packed basic electrodes
 Extra low Hydrogen Content.
 Tin Can
Packaging
Using Condition
Other notes
 Use straight from the box - No baking/drying!
 If necessary, dry up to 120°C
 Electrodes can be dried to lower H2 content
but cannot be baked as it will destroy the
coating.
 Careful control of baking and/or issuing of electrodes is essential to
maintain low hydrogen status and avoid risk of cracking.
 Suitable dry and Warm (preferably 0% humidity)
 They should be baked in oven for 1 or 2 hours at 350°C
 After baking maintain in oven at 120°C : 150°C
 Use from quivers at 75°C
 If not used within 4 hours, return to oven and rebake
 Note that you have a limited numbers of rebakes.
 Some may be tipped with carbon compound to ease
arc ignition.
 Arc ignition enhancing materials (optional!) on the
tip
 See BS EN ISO 544 for further information,
Welding consumables. Technical delivery
conditions for filler materials and fluxes. Type of
product, dimensions, tolerances and markings
Baking Oven
 Iron Powder Electrode
% 100 ‫ عا ا من‬Recovery ‫ دا ال ود ب دي‬
‫بتاعو ف ه بودرة حد د فب معاك‬Coating ‫ ﻻنو ب كون مان ال‬
 Recovery Efficiency can reach 120% 130% 150% and 160%
Heated Quivers
 Use straight from the box - No baking/drying!
 Not require baking or drying (excessive heat will
damage electrode covering).
Electrode Efficiency (η) -Recovery Efficiency (η) - Deposition
Efficiency (η)
 Ratio of mass of weld metal deposited to the mass of the core
wire.
High Recovery Rutile Electrodes.
 Rutile Electrode with Coating is bulked out with iron powder
Composition
Resulting weld
Quality
 Large weld beads with smooth profile can look very similar to SAW welds.
Advantages
 Iron powder gives the electrode high recovery/productivity.
 Extra weld metal from the iron powder can mean that weld deposit from a single electrode can be as
high as 180% of the core wire weight.
Hydrogen content
 Same as standard rutile electrodes with respect to hydrogen control.
 Rutile Electrode
 High Hydrogen content.
 Hydrogen content is 25-30 ml/100g of weld metal.
 They cannot be made with a low hydrogen content.
 𝐸𝑙𝑒𝑐𝑡𝑟𝑜𝑑𝑒 𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑦 (𝜂) =

‫ام من وزن اﻻل ود حي ل و تحول فعل ا لمعدن لحام‬

If recovery efficiency = 93 % for example this means that out of
each electrode weight before welding you will have a 93 % of its
weight as a weld metal and the remaining 7% will be lost.
 Large weld beads produced cannot be used for all-positional welding.
 The very high recovery types usually limited to PA and PB positions.
 More moderate recovery may allow PC use.
Electrode Type
Usual electrode
Iron Powered electrode
Positions
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Typical Values for Efficiency
75% : 90%
120%, 130%, 150%, 160%
TYPES OF ELECTRODES for (C and C-Mn Steel)
Electrode
BS EN 2560
Rutile
E XX X R
Rutile Heavy
Coated
E XX X RR
Basic
E XX X B
Cellulosic
AWS 5.1
EXX12
EXX13
EXX24
EXX15
EXX16
EXX18
EXX10
EXX11
E XX X C
MMA Advantages and Disadvantages.
Advantages
Consumables
1.
2.
3.
4.
Positions.
5. All Positions
Equipment
Disadvantages
Simple Equipment
Very Portable
Field or Shop Use
Range of Consumables
Equipment / Welder
Consumable
1.
2.
3.
4.
Semi-Automatic and
Automatic Welding
Process
Operating Factor
MMA
TIG
MIG/MAG
30%
N/A
 Manual & semi ~ 60%
 Full automatic ~ 90%
N/A
FCAW/MCAW
SAW
N/A
Electrode Efficiency (η) -Recovery Efficiency (η) - Deposition Efficiency (η)
 Ratio of mass of weld metal deposited to the mass of the core wire.
 𝐸𝑙𝑒𝑐𝑡𝑟𝑜𝑑𝑒 𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑦 (𝜂) =

‫ام من وزن اﻻل ود حي ل و تحول فعل ا لمعدن لحام‬

If recovery efficiency = 93 % for example this means that out of each electrode
weight before welding you will have a 93 % of its weight as a weld metal and the
remaining 7% will be lost.
Electrode Type
Usual electrode
Iron Powered electrode
Equipment
Welder/Fitter
Consumables
Incorrect settings of equipment.
Lack of welder skill.
Incorrect use or treatment of electrodes.
5. Arc Strikes and Slag Inclusions.
Defects
Operating factor: (O/F)
 The percentage of arc on time in a given time.
 Jeffus Book, Operating factor is the percentage of a welder’s working day actually
spent on welding.
 O/F can be directly linked to productivity.
 A 45% (0.45) operating factor means that only 45% of the welder’s day is actually
spent on welding. The rest of this time is spent installing a new electrode or wire,
cleaning slag, positioning the weldment, cleaning spatter from the welding gun,
and so on.
Manual Welding
Causes of MMA Welding Defects
Low productivity “Low Operating Factor”
High welder skill
High level of fumes
Hydrogen Evolution (Flux)
Typical Values for Efficiency
75% : 90%
120%, 130%, 150%, 160%
Duty cycle
It is a safety value
given as the % of time a conductor can carry a current
It is given as a specific current at 60% and 100% of 10 minutes.
Jeffus Book, The percentage of time a welding machine can be used continuously.
Example on value

350A 60%
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300A 100%
 A 60 % Duty Cycle means that our of any 10 minutes, the machine can be used for
a total of 6 minutes at the maximum rated current
 When it provides power at this maximum rated current and for 6 minutes, it must
be cooled off for 4 minutes.
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