Selecting the Electrode
Shielded Metal-Arc Welding
Chapter 6
• Electrodes
– Classified into 5 main groups
• Mild steel
– Majority of welding
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High-carbon steel
Special-alloy steel
Cast iron
Non-ferrous
– Ex. Aluminum, Copper, & Brass
• Electrode – a coated metal wire having approximately
the same composition as the base metal.
• Standards set forth by AWS (American Welding
Society) & ASTM (American Society for Testing
Materials)
• Two kinds of mild steel electrodes
– Bare & Shielded
• Bare electrodes are still covered with little covering, this limits their
use in the welding field.
• Shielded electrodes have a heavy coating on the outside of them (flux)
• Purpose of flux- prevents corrosion from taking place
– Act as a cleaner and deoxidizes
– Release an inert gas to protect from oxygen, nitrogen, & hydrogen
in the atmosphere. These elements will weaken the weld if they
were to come in contact with the molten metal.
– Form slag to protect the cooling metal & allows metal to cool at a
slower rate protecting the metal properties.
– Provide easier starting arc, stabilizer, reduce splatter.
– Permit better penetration & X-ray quality.
• Flux
– As the electrode burns the flux produces a gaseous shield
around the weld.
– This prevents harmful contaminants from hurting the
weld.
– 3 harmful elements present in the atmosphere
• Hydrogen
• Oxygen
• Nitrogen
• Consider the following when selecting an electrode:
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The weld groove design
Tensile strength of the required weld
Base metal composition
Electrode diameter 1/8, 3/32, 5/32 (never use a rod with a
diameter larger than the thickness of the base metal)
• Electrode size means the size of the wire, not overall size of the rod
– Amp setting: simple way divide the rod thickness 1/8= 125amps
– The position of the weld joint
– The rate at which you want to deposit the weld metal
• The shape of the deposited bead (filler) is caused by oscillation
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The type of current used
Penetration required
Metal thickness
The experience of the welder
The specifications of the weld to be made
QUIZ
• Identifying Electrodes
– Standards set up by AWS (American Welding Society) &
ASTM (American Society of Testing Materials)
• Prefix E stands for electric arc (E-6010)
• The first two digits stand for tensile strength in thousands psi
(60,000)
• The third digit represents welding position (1,2,3)
– 1= any position
– 2= horizontal & flat position
– 3= flat position only
• The fourth digit represents a manufacturers special
characteristic
– The numbers 0 – 8 may used
• Conserving & Storing Electrodes
– Electrodes are very expensive so use them up to 1 ½” to 2” in
length. (do not burn them into the stinger handle)
– Always store electrodes in a dry place at normal room temp
“Moisture will cause the flux to
crack & disintegrate”
Please burn electrodes to this length!!!
• Fast freeze electrodes
– Deep penetrating arc & fast-freezing deposits (commonly
called reverse polarity electrodes)
• Fill-freeze electrodes
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Moderately forceful arc & deposition rate
Commonly called straight polarity rods
General purpose electrode
Can be used in all positions
Preferred in vertical & overhead welding
• Fast-fill electrodes
– Heavy coated iron powder electrodes with soft arc & fast
deposit rate
– Heavy slag & exceptionally smooth beads
– Generally used for flat welding (production work)
• Characteristics of Common SMAW Electrodes
– E-6010
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Covering/Flux: cellulose-sodium & 0-10% iron powder
Position: All Current: DCRP Penetration: deep
Arc: Digging Freeze: fast Fill: medium slow
Slag: light, easy to remove (wire brush is better)
Bead Appearance: flat, rough & much spatter.
Quality of fit-up for successful weld: poor to good
Average amperage: 1/8” rod = 70-100 amps
* E-6010 is only for reverse polarity, so it is sometimes used to check
polarity. It will give a strong hissing arc if the incorrect polarity is
being used. Try it in your booth & become familiar with it.
E-6010
– E-6011
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Covering/Flux: cellulose-potassium & 0-10% iron powder
Position: All Current: AC or DCRP Penetration: deep
Arc: digging
Freeze: fast
Fill: medium-slow Slag: light, easy to remove
Bead Appearance: flat, rough & much spatter
Quality of fit-up for successful weld: poor to good
Average Amperage: 1/8” rod 70 – 110 amps
– E-7018
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Covering: low-hydrogen & 25-40% iron powder.
Position: All Current: DCRP Penetration: medium
Arc: medium Freeze: medium Fill: fast
Slag: heavy & hard to remove
Bead Appearance: medium smooth with some spatter.
Quality of fit-up for successful weld: good
Average Amperage: 1/8” rod 100 – 150 amps
E-7018
Next E-6010E-6011 video
Back to E6013 outline
Cont. E-7018
video
Cont. Notes
A = correct current,
arc length & travel
speed
B= Amperage too low
C = Amperage too
high
D = Too short an arc
length
E = Arc length too
long
F = travel speed too
slow
G = Travel speed too
fast
Striking an Arc
2 methods
Stringer Bead
Weave
• Tie-Ins
– Always remove
slag from
previous weld
– Chipping
hammer or wire
brush
AWS Pipe Welding Positions
• 5G – Pipe is horizontal & the joint is vertical
– May be welded uphill or downhill
• Uphill welding – starting the weld at the bottom or 6 o’clock
position and moving upward to the top of the joint or 12
o’clock position.
• Uphill welding usually produces:
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Better penetration
Fewer passes are required
Used on thicker-walled pipe
Used on high-pressure pipe welds
• Downhill welding – starting the weld at the 12 o’clock position
and is welded downward towards the 6 o’clock position.
– The welds must move more rapidly to prevent molten slag from rolling
into the weld pool.
– Penetration is better when welding uphill.
– Downhill is used on pipe with wall thickness thinner than ½”
Pipe welding Passes
• Root pass – 1st pass on pipe
– Remove slag after root pass
– Usually performed with E-6010 or E –7010
– The root pass is usually ground out partially to remove
any crown in the 1st pass.
• Penetration is essential in the root pass, therefore GTAW is
sometimes preferred for this pass for the highest quality.
• Hot pass – 2nd pass on pipe
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Hot pass uses more current than the root
It must fuse well with the root pass & pipe walls
It must melt any slag left from the root pass
The hot pass should be welded within five minutes after
the root pass is completed.
• Filler passes
– Used to fill the weld joint – several are performed
– May be stringer beads or slight weaves
– Each pass must fuse the previous pass & into the pipe
walls
– To prevent slag inclusions, each pass must be cleaned
prior to welding the next pass
• Cover pass – final pass
– Used to cover the weld joint
– Weaving motion is used to produce a wide bead
• Hot, filler, & cover passes are made with E-6010 or E-7010, &
E-7018 electrodes.
• E-6010, E-7010 are used with downhill welding.
• E-7018 are used with uphill welding
• When a backup ring is used E-7018 can be used for the root
pass.
Two pipe welders welding in the 5G position
• 2G – Horizontal Pipe Welding
– Similar to horizontal welding on plate
– Before attempting to weld in the 5G position, a person
must be able to weld satisfactorily in the flat, vertical, &
overhead positions.
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1G – Rotated Flat Pipe Welding
– Same as 5G, but pipe is rotated mechanically
• 6G – Multiple pass
– Pipe is angled with multiple passes, but it is not rotated.
Backing ring for pipe butt
joints. This device helps
control penetration & aligns
the pipe. Used with E-7018
AWS Welding Positions for Groove Welds: Plate
• 1G Flat Position:
• 2G Horizontal Position
• 3G Vertical Position
• 4G Overhead Position
AWS Welding Positions for Fillet Welds: Plate
• 1F Flat Position:
• 3F Vertical Position
• 2F Horizontal Position
• 4F Overhead Position