1. Selecting the Electrode
Shielded Metal-Arc Welding
Chapter 6

2. Electrodes
Classified into 5 main groups
Mild steel
Majority of welding
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)

3. 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.

4. 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

6. Consider the following when selecting an electrode:
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
The type of current used
Penetration required
Metal thickness
The experience of the welder
The specifications of the weld to be made
QUIZ

8. 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

10. 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)

11. Fill-freeze electrodes
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)

12. Characteristics of Common SMAW Electrodes
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 = 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

13. E-6011 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

14. E-7018 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

15. Next E-6010-E-6011 video

16. Back to E-6013 outline

17. Cont. E-7018 video

18. Cont. Notes

19. 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

20. Striking an Arc
2 methods
Stringer Bead
Weave

22. Tie-Ins Always remove slag from previous weld
Chipping hammer or wire brush

23. 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:
Better penetration
Fewer passes are required
Used on thicker-walled pipe
Used on high-pressure pipe welds

24. Root pass – 1st pass on pipe
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.

25. Hot pass – 2nd pass on pipe
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

26. 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.

27. Two pipe welders welding in the 5G position

28. 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.
1G – Rotated Flat Pipe Welding
Same as 5G, but pipe is rotated mechanically

29. 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

30. AWS Welding Positions for Groove Welds: Plate
1G Flat Position:
2G Horizontal Position
3G Vertical Position
4G Overhead Position

31. AWS Welding Positions for Fillet Welds: Plate
1F Flat Position:
2F Horizontal Position
3F Vertical Position
4F Overhead Position