SMAW: Mild Steel Electrodes Flashcards
The ability of a metal to permanently deform under load without breaking is known as
Ductility
The ultimate pull that a material can withstand is called
Tensile strength
Impact tests such as izod or charpy are designed to measure
The welds impact strength
The point at which a material begins to deform permanently under load is called it’s
Yield point
Dynamically loaded structures are subject to
Reversals of stress
Which is the best example of dynamically loaded structure
The boom on a crane making a lift and then swinging the load
A static load means that the load
Is steady and relatively unchanged
Which is the best example of statically loaded structure
The column supporting the wall in a building
Electrodes used in SMAW are often called
Consumable electrodes
Electrode specifications are written by
CSA and AWS
In AWS classification for SMAW mild steel electrodes what does the last digit represent
The major ingredient in the coating and the recommended current for best results
What do the first two digits in the AWS classification for carbon steel SMAW electrodes represent
As welded min tensile strength
In the CSS numbering system for welding electrodes what does the prefix letter E represent
Electrode
According to AWS which number indicates the position an R7024 can be used in
Third number
The CSA system used what term to measure tensile strength
Megapascals MPa
Which set of characteristics best describes the electrode E4914 / 7014
Rutile coating, 30% metallic powder, AC or DC either polarity
E7024 electrodes are designed to be used in which positions
Flat and horizontal
What is the difference between an E7018 and an E7028 electrode
E7018 can be used in all positions
E7028 cannot
True or false
E7038 can only be welded in the flat position
True
True or false
E6010 has the least amount of metallic iron powder in its coating
True
What is one difference between an E7010 electrode and an E7018 electrode
Coating
What is one characteristic of an E6010 electrode
Deep penetration into the base metal
What is the major difference between the coatings of an E4310 and an E4311 electrode (6010 and 6011)
An E4311 has potassium added as an arc stabilizer for AC welding
Why is iron powder added to the coatings of some electrodes
To increase the rate of weld deposits
Which electrode has a cellulose coating
E6010
Which electode contains the highest amount of iron powder in its coating
E7014
What is one purpose of the slag produced from the flux coating on a welding electrode
To protect the molten weld puddle from atmospheric contamination
Which last digit in the classification of a smaw mild steel electrode describes a flux that is lime based
8
Adding large amounts of iron powder to electrode coatings would limit welding to which positions
Flat and horizontal
What is one function of the slag produced from electrode coatings
To prevent the weld from cooling too rapidly
Which statement is true about the slag produced when welding with a coated electrode
It helps prevent oxygen and nitrogen from contaminating the weld
What is the likely effect of using low hydrogen electrodes with a moisture content that exceeds the acceptable limits
The weld metal will probably have porosity and may develop hydrogen induced cracking
What is the main purpose for keeping low hydrogen electrodes dry
To minimize the possibility of hydrogen induced cracking
What is the recommended moisture content for E6010 electrode coatings
3% - 7%
Proper handling of electrodes includes following the manufacturer’s recommendations regarding
Storage and reconditioning procedures
To weld thin materials you would likely select a electrode with
A small diameter core wire
Which electrode works best for the root bead on groove welds with an open gap
E4310 / 6010
What is the major advantage of using an E4310 for the root bead and E4918 electrodes for fill passes on one welded joint
It takes advantage of the penetration qualities of the E4310 and the mechanical properties of the E4918
It is important to know the chemical and mechanical properties of the base metal so you can select an electrode with the correct
Flux coating
Which electrode would be best choice if the base metal properties were unknown
E7018
High impact strength (lack of brittleness) is a good indication of ….
Toughness
A leaf spring is a good example of a steel that has been _______ to a high degree of toughness.
Tempered
Non consumable electrodes
GTAW - Tig
Not intended to be consumed into the weld puddle. An electric arc is drawn between a non consumable tungsten electrode and the work
Consumable electrodes
SMAW
The electrode is melted into the weld puddle (consumed) a consumable electrode = filler metal bc the metal from the electrode is melted into the weld
Mechanical properties of metal
Ductility, tensile strength, brittleness, hardness, toughness, elasticity, malleability, yield strength, impact strength
Physical properties
Colour, shine, density/weight, thermal conductivity, electro conductivity
The ability of a material to stretch or deform under load without breaking
- expressed as a percentage of elongation
Ductility
The ultimate pull that a material can stand
PSI or MPas
Tensile strength
Necking
Where the metal pulls in and ultimately breaks
Ultimate tensile strength
The peak of the strength not when it breaks
The point that permanent deformation takes place
Yield or Elastic Limit
When you pull and it keeps that new shape
Plastic
You pull and it goes back to original form
Elastic
Defined as it’s ability to resist penetration or indentation resist scratching or abrasions
Hardness
Uses a diamond to test hardness
The hardness number is read directly from a gauge that measures the depth of the indentation
Used on harder material
The Rockwell system
Measures the diameter of the steel ball impression made
Used on softer material
The Brinell hardness tester
The ability of metal to withstand rapidly applied load without breaking
Toughness
Controlled heating to draw some of the hardness out of a metal to promote toughness
(A leaf spring is a good ex of a steel that has been tempered to a high degree of toughness)
Tempering
Ability of a metal to return to its original shape and dimensions once the load has been removed
(Tungsten filler rod)
Elasticity
Ability to be cold worked with out a great deal of resistance.
Bends slightly or shows some distortion before breaking, doesn’t snap back
Malleability
Ability of a metal to withstand a sharp high velocity blow
Measured in foot, pounds or joules
Impact strength/ fracture toughness
Impact strength/ fracture toughness tests
Izod and charpy tests
Uses a weighted swinging pendulum to break a botched specimen at dif temps
Crane booms, truck frames, farm tillage are an example of what loading
Dynamic loading
Occurs when a structure is subject to rapidly changing loads
Reversal of stress
Stationary or relatively unchanging
Ex base plates, metal storage racks or beams that support building roofs
Less ductile, harder rod
Static loading
Filler wire classified by
AWS and CSA
Welding positions
1, 2, 3, 4
1: all postition
2: flat and horizontal
3: flat only
4: flat, overhead, horizontal and vertical down
7048
Bohler rod
Down hand rod
0: paper flux: DCRP
6010, 7010, 8010
Cellulose
AIT: 6010 is a good polarity checking rod bc it only works on DCRP
2, 3, 4: mineral titanium : titanium dioxide : arc stabilizer and slag former
6012, 6013, 7014, 7024
Rutile
5, 6, 8: Thick heavy slag/ductile
7015, 7016, 7018m, 7028, 7048
Lime (limestone) / calcium carbonate
Low hydrogen
7: rust, good for welding on dirty/rusty material
6027, 7027
Iron oxide
Exceptions
6020: used on thicker base metals
6022: high speed, high current welding
Bc of the 2 in the third placement assume iron oxide. Amount of filler metal added to the flux can only be welded in the flat and horizontal
Hydrogen
Causes hydrogen cracking, keep hydrogen as low as possible.
The suffix 1H4 shows hydrogen levels
H4 meets requirements of H8 and H16
The lower the number the better
1 means electrode meets optimal supplemental impact strength requirements at low temp
R in the suffix means
Resistant to moisture absorption
(Why we use rod ovens)
E4310
E6010
E4918
E7018
E5518
E8018
AWS suffix
H2, H4, H8
H2: meets requirements of H4, H8 and H16
H4 meets requirements of H8 and H16
H8 meets requirements of H16
Can be burned out by other passes
Ex 6010/ 4310
Friable
6010/ 4310
Penetration, slag, bead, qualities
Flux: cellulose
Penetration: deep
Slag: thin, friable, easy to remove
Bead: flat weld face, coarse ripples
Qualities: dynamic loading, fast freeze
All position, DCRP only
Stored beside oven
Moisture content should range between 3-7%
7018 / 4918
Penetration, Slag, bead, qualities
Lime
All positions
Penetration: medium
Slag: heavy, friable, easy to remove
Bead: smooth concave, fine ripples
Qualities: dynamic loading, low hydrogen weld deposit
6013
Penetration, slag, bead, qualities
Rutile
All position
Penetration: low
Slag: easily removed slag
Bead: flat fillet, smooth, fine ripples
Qualities: static loading, light sheet metal
7024 / 4924 jet rod
Penetration, slag, bead, qualities
(Puts down all the metal fast)
Iron oxide
Flat and horizontal position only
Penetration: low penetration
Slag: easy to remove, sometimes removes itself
Bead: smooth, fine ripples
Qualities: static loading, high deposit rate
6011
Penetration, slag, bead, qualities
Cellulose
All position
Penetration: deep
Slag: thin friable, easy to remove
Bead: flat weld face, coarse ripples
Qualities: dynamic loading, fast freeze
Can run AC and DCRP it’s similar to 6010
Has added potassium silicate which is an arc stabilizer
1 inch = ______ mm
25.4 mm
Core wire is made of what steel
Rimmed / cheapest
Flux v slag
Flux when it’s on the rod
Slag on the weld
Increases deposition rate by 50% or more
Iron powder
- High current: more current is needed to melt the iron powder in the coating
- a deep cup (crucible cup) is formed on the end of the electrode the core wire melts slightly ahead of the flux
- drag technique: arc length becomes self regulating with electrode that form a crucible cup if you use the drag technique
3 electrode operating characteristics can be controlled by
- Fast freeze: speed at which weld puddle solidifies
- Fast fill: amount of filler metal produced
- Fill freeze: speed at which filler metal deposited
Fast freeze electrode
Ability to solidify quickly
Penetrates deep
Little slag
Vertical or overhead
E4310 (E6010)
Fast fill electrode
Deposit a weld with a substantial amount of filler metal at a fairly fast rate
Production welding
Jet rod E4924/ E7024
Flat and horizontal positions
Fill freeze electrodes
Rapid deposit of narrow, shallow penetrating weld bead with crater following rapidly behind arc
- little filler metal is needed
- light gauge sheet metal
- straight polarity = less penetration
- E4913 / E7013
Slag functions
Excludes oxygen and nitrogen from weld until cool
Prevent hard, brittle weld
Dissolves impurities in molten weld pool/ floats them to surface
Controls shape and smoothness of bead
Slow down cooling rate
Reasons for slag to be difficult to remove
Improper weld technique
Incorrect current setting
Wrong current type
Incorrect travel speed
Wrong welding position
Lime coated electrons should be packaged
Hermetically sealed (air tight) containers and placed in an electrode holding oven
30-140 C (50-250 F)
Which polarity tends to cause arc blow
Direct current DC
Describe the difference between a constant current machine volt amp curve and a constant potential volt amp curve
Constant current: SMAW GTAW
Drooping volt amp curve
Constant potential/ constant voltage:
Wire feed
Relatively flat volt amp curve
What electrical factor influences the metal deposition rate? What happens when this factor increases or decrease
An increase in amperage = increase in metal deposition and vice versa
What does NEMA stand for and what is their role when it comes to welding
National electrical manufacturers association
Rates all welding machines, max rated output in 10 min before it has to cool down
What is the purpose of a rectifier
Changes an AC machine to a DC machine with use of a diode
When SMAW welding with reverse polarity where is 2/3 of the energy located
2/3 of the arc energy is with the base metal (negative terminal)
When SMAW welding with straight polarity what happens to metal flow and penetration
Electrode melts faster
Less heat in baseplate
Wide puddle
Shallow penetration
Think metals, cladding, hardfacing
(Electrode negative, clamp/work piece positive)
What does electromotive force (EMF) influence while welding?
EMF is the voltage
- starting the arc
- maintaining the arc
- puddle fluidity
- puddle flow
When blowing dust and debris out of a welding machine what type of air should u use
Low pressure air
Name the welding cables in order from least resistance to most resistant
(Least) 4/0, 3/0, 2/0, 1/0, #1, #2, #3, #4 (most)
Why it is important to ensure your work lead has a tight clean connection
Poor connection can cause accidental arcing at the work lead, cause extreme hard and brittle spots to form on workpiece
Resistance to current flow, creates unstable arc, overheating welding cables
Describe how arc length can influence your weld puddle
Short: more narrow and deeper penetration
Normal: larger puddle and less penetration
Long arc: bigger puddle, shallow penetration, well on thin metals
F1
Iron
F2
Rutile
F3
Cellulose
F4
Lime
Holding oven temp
50F - 250F
Re bake oven temp
500F - 800F
