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Weld Inspection
Level 1
Introduction to Welding
Definition
Introduction to Welding
Welding Terminology
Physics of Welding
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DefinitionWelding: A group of processes used to join metallic and
nonmetallic materials. Often done using heat but maybe
done using pressure or a combination of heat and pressure.
A filler material may or may not be used.
Other processes: riveting, forging, cutting, turning, and bending
First used: 2000 BC
Modern methods: 1881
Examples of Welding Processes
Shielded Metal Arc
Gas Tungsten Arc Welding
Gas Metal Arc Welding
Submerged Arc Welding
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Shielded Metal Arc Welding
Gas Tungsten Arc Welding
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Gas Metal Arc Welding
Submerged Arc Welding
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Introduction to Welding
Joint between the materials is melted
Intermixing occurs
Upon solidification a metallurgical bond results
The weld has the potential to have same strength as the
materials being joined
Unlike soldering, brazing and adhesive bonds which are
not fusion processes
Arc Welding
Intense heat to melt metal is produced by electric arc
Arc between electrode and metal to be joined
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Shielded Metal Arc Welding
High current, low voltage, AC or DC
The Arc
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Heat in The Arc
Change the arc length
Change the shielding gas
Addition of potassium salts reduces arc voltage
Metal Arc Transfer
Metal is transferred across the arc (consumable electrode)
Mechanism of transfer:
Molten metal drop touches and transfers by
surface tension
Magnetic pinch effect
Gravity (flat welding)
More heat is transferred than non-consumable electrodes
Ionization column must be present to conduct electricity (arc)
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Electrical Supply
AC
DC, electrode positive
DC, electrode negative
Selection depends upon:
Process
Type of electrode
Arc atmosphere
Metal being welded
Properties of Metals
Physical
Chemical
Mechanical
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Physical Properties
Colour
Melting Temperature
Density (weight per unit volume)
Chemical Properties
How the metal reacts in an environment
Corrosion Resistance (ability to resist corrosion)
Oxidation Resistance (ability to resist combining with oxygen)
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Mechanical PropertiesStrength (ability to resist load without failing)
Tensile strength (ability to resist pulling force)
Compressive strength (ability to resist crushing force)
Ductility (ability to deform without breaking)
Brittleness (inability to resist fracture)
Toughness (ability to resist cracking)
Hardness (ability to resist indent or scratching)
Grain size (important in determining mechanical properties)
Effects of Welding
Heat creates stress, affects ductility and toughness
Effects of previous heat treating are lost around the weld
If done properly usually stronger than the base metal
Can effect the chemical resistance
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Expansion and Contraction
Metal expands when heated
Metal contracts when cooled
Expansion and contraction creates stress
Welding jigs or fixtures prevent movement but lock in stress
Butt Joint Root Opening
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Butt Joint Root Opening
Butt Joint Distortion
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Tee Joint Distortion
Reducing Distortion & Stress
Tack weld
Align parts for contraction
Use jigs or fixtures
Preheat parts
Heat treat welded parts
Proper welding procedures
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Heat Treating
Pre heating
Raise the temperature just prior to welding
Entire part is heated
Less contraction and stress on cooling
Heat Treating
Interpass heating
Heating while welding or between passes
Minimize expansion and contraction
Reduce stress
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Heat Treating
Annealing
Heat treatment after welding
Heated above critical temperature
900° C for mild steel
Held at temperature for 1 hour per inch of thickness
Slow cooled
Heat Treating
Stress Relieving
Heat treatment after welding
Heated below transition temperature
650° C for mild steel
Held at temperature for 1 hour per inch of thickness
Air cooled
Relieves some of the stress of welding
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Electrical Principles
Voltage
Force that causes electrons to flow in a circuit
Similar to pressure
Measured in volts
Electrical Principles
Resistance
Opposition to flow of electrons measured in ohms
Air gap is resistance
If voltage is not sufficient to overcome resistance
of gap no arc exists
Higher voltage allows a longer arc
Arc stops if voltage is not high enough
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Electrical Principles
Current
Flow of electrons measured in amperes
Compared to flow of water
If there is no arc, no current flows in welding circuit
Units of Measure
Micro [µ] = 1/1,000,000 or .000001
Milli [m] = 1/1,000 or .001
Centi [c] = 1/100 or .01
Deci [d] = 1/10 or .1
Kilo [ K] = 1,000
Mega [M] = 1,000,000
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Terminology
Welding Technology Fundamentals
Page 441
Procedures Handbook of Arc Welding
Page 16.1-1
Basic Weld Joints
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Butt Joints
Parts of a Grooved Butt Joint
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Corner Joint
T - Joint
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Edge Joint
Fillet Welds
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Engineering Drawings
Isometric Projection
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Orthographic Projection
Orthographic Projection
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Orthographic Projection
Orthographic Projection
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Orthographic Projection
View Selection
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First and Third Angle
Projection
First and Third Angle
Projection
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Drawing Lines
Dimensioning
S = size
P = position
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DimensioningAngles Chamfers
Tapers
Auxiliary Views
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Sectional Views
Sectional Views
Mating parts
Typical cross section
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Thread Illustrations
Team Project 2
Prepare a sketch in third angle orthographic projection
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Preparation of Joints for
Welding
Preparation of Joints for
Welding
Flanged Preparation
e = member thickness
Used of relatively thin material
Medium efficiency
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Preparation of Joints for
Welding
Square Butt Preparation with backing
g = root gap
Improves probability or full penetration
Stress raisers that affect fatigue performance
Preparation of Joints for
WeldingSingle Vee Preparation
ß = bevel angle, α = groove angle, s = root face,
g = root gap, = solid angle
Optimum joint efficiency require back gouging and
welding
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Preparation of Joints for
Welding
Single Bevel Preparation
α = groove angle, s = root face, g = root gap,
Ω = angle of incidence
Used for Tee and corner joints
Optimum joint efficiency require back gouging and
welding
Preparation of Joints for
Welding
Single U Preparation
α = groove angle, s = root face, g = root gap,
β = bevel angle, r = root radius
Reduced volume of weld as compared to Vee,
less distortion
Optimum joint efficiency require back gouging and
welding
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Preparation of Joints for
WeldingPartial U Preparation
α = groove angle, s = root face, g = root gap,
d = depth of prepared edge, r = root radius,
b = root width
Preparation of Joints for
WeldingDouble Vee Preparation
α = groove angle, s = root face, g = root gap,
β = bevel angle, d = depth of of prepared edge
Reduced distortion and weld volume compared to
single Vee, back gouging preferred before
welding second side
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Preparation of Joints for
WeldingDouble Vee Preparation with Broad Root Face
α = groove angle, s = root face, g = root gap,
d = depth of prepared edge
Used in SAW
Preparation of Joints for
WeldingDouble U Preparation
α = groove angle, s = root face, g = root gap,
β = bevel angle, d = depth of of prepared edge
Used for thicker sections
Reduced volume of weld as compared to Vee,
less distortion
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Preparation of Joints for
WeldingDouble J Preparation
α = groove angle, s = root face, g = root gap,
d = depth of prepared edge, r = root radius
Preparation of Joints for
WeldingPartial Double J Preparation
α = groove angle, s = root face, g = root gap,
r = root radius, d = depth of of prepared edge
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Preparation of Joints for
WeldingMixed Preparation
α = groove angle, r = root radius, l = half width of flat bottom
Welding Symbols
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Welding Symbols
L-P
FAR
S (E)T
N
L-P
FAR
S (E)T
N
Weld-all around
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L-P
FAR
S (E)T
N
Field Weld
L-P
FAR
S (E)T
N
Reference Line
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L-P
FAR
S (E)T
N
Tail(Tail omitted when references not used)
L-P
FAR
S (E)T
N
Specification, process or other reference
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L-P
FAR
S (E)T
N
Depth of penetration, size or strength
L-P
FAR
S (E)T
N
Groove weld size
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L-P
FAR
S (E)T
N
Basic weld symbols
L-P
FAR
S (E)T
N
Finish symbol
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L-P
FAR
S (E)T
N
Finish contour
L-P
FAR
S (E)T
N
Groove angle
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L-P
FAR
S (E)T
N
Root opening
L-P
FAR
S (E)T
N
Number of spot, stud or projection welds
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L-P
FAR
S (E)T
N
Length and pitch
Basic Weld Symbols
L-P
FAR
S (E)T
N
Designates the specific type of weld
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Basic Groove Weld Symbols
Square
Single V
Single bevel
Double J
Double flare
Fillet and Plug Weld Symbols
Fillet
Plug
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Single and Double Welds
Single Double
Bevel Groove
J Groove
Flare
Fillet
Arrow Significance
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Arrow Significance Groove
Welds
Arrow Significance Groove
Welds
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Arrow Significance Fillet
Welds
Arrow Significance Fillet
Welds
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Information in the Tail
L-P
FAR
S (E)T
N
Specification, process or other referenceWelding process
Welding procedure
“Typical” representative of all welds on the drawing
Field Weld
In a place other than original construction
Usually in the erection phase
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Melt-thru Symbol
Extent of Welding
If length is not specified
length is between abrupt changes in direction
Length maybe directly dimensioned on drawing
Weld all around symbol
L-P
FAR
S (E)T
N
Weld-all around
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Uses of Weld All Around
Finishing of Weld
C Chipping
G Grinding
M Machining
R Rolling
H Hammering
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Break in Arrow
Arrow points to member to be chamfered
Combined Welding Symbols
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Alternate Combined Welding
Symbols (AWS A2.4)
Complete Penetration
Note: CJP = Complete joint penetration
or CP = Complete penetration
GTSM = Grind to sound metal
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Groove Welds
Key parameters:
Depth of penetration
Bevel angle
Root opening
Three Basic Angles
Θ1 = Bevel angle
Θ2 = Groove angle
Θ3 = Angle at root
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Dimensioning Double Groove
Welds
Depth of Penetration &
Groove Weld Size
L-P
FAR
S (E)T
N
L-P
FAR
S (E)T
N
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Depth of Penetration &
Groove Weld Size
E may be greater or smaller than S
Practice
Single Groove
Partial Penetration
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Practice
Single Groove
Partial Penetration
Practice
Single Groove
Partial Penetration
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Practice
Single Groove
Partial Penetration
Practice
Double Groove
Partial Penetration
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Practice
Double Groove
Partial Penetration
Practice
Double Groove
Partial Penetration
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Practice
Double Groove
Partial Penetration
Practice
Double Groove
Full Penetration
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Practice
Double Groove
Full Penetration
Practice
Double Groove
Full Penetration
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Practice
Square Groove
Square Groove
Requires Full Penetration
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Square Groove
Symmetrical Double Groove
Welds
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Optional Joint Preparation
Complete Penetration With
Back-gouging
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Complete Penetration With
Back-gouging
Complete Penetration With
Back-gouging
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Flare Weld
Flare Weld
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Surface Finish
Most common is flush
Welds With Backing
Basic Symbol
M = Material of backing bar
R = Removal of backing bar after
welding
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Welds With Backing
Backing bar size can be placed in tail
S = SteelR = Removed
Joints With Spacers
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Combination Groove and Fillet
Sequence of Preparation
Solid lines indicate preparation before fit-up
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Sequence of Preparation
Solid lines indicate preparation before fitting
CSA W59
Fillet Welds
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Fillet Welds
Note: vertical side (line) always on left
Equal-legged
Fillets
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Fillet Size
S = Specified size (size on symbol)
Seff = Effective size (size that corresponds to
specified size)
Sm = Measured size (based on actual measurement)
Fillet Size
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Fillet Size
Some countries specify the size of fillet by throat
rather than leg
In Canada and USA we use leg
ISO (ISO/TC44/SC7) recognizes both, but requires
identification:
“z” designates leg size
“a” designates throat size
Fillet Size
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Unequal-legged Fillet Welds
Size is shown in brackets as:
(S1 x S2)
Not leg specific
Unequal-legged Fillet Welds
or
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Unequal-legged Fillet Welds
Often the which leg size is governed by
geometry of joint
Fillet Sizes (With Gaps)
Gaps less than 1mm (CSA W59)
or 1/16 (AWS D1.1)
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Fillet Sizes (With Gaps)
Gaps greater than 1mm (CSA W59)
or 1/16 (AWS D1.1)
Maximum gap
5mm for material < 75mm thick
8mm for material > 75mm thick
Measured size increased
by amount of gap
Fillet Welds in Skewed
Connections
Beyond this range, weld is considered partial
penetration (CSA W59 and AWS D1.1)
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Fillet Welds in Skewed
Connections
It is necessary to show a sketch of the weld with
dimensions
Length of Fillet Welds
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Length of Fillet Welds
Length of Fillet Welds
(Not Specified)
Considered to run length of joint to change of
direction
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Length of Fillet Welds
(Not Specified)
Fillet
All-around
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Intermittent Fillet Welds
Intermittent Fillet Welds
Common Centre Symbols Aligned
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Intermittent Fillet Welds
Staggered Centres Staggered Symbols
Fillets Welds
With Terminal Ends
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Fillets Welds
Surface Finish & Contour
Plug and Slot Welds
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Plug and Slot Welds
Plug and Slot Welds
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Plug Welds
Key Parameters:
Diameter of hole
Angle of countersink
Depth of filling
Spacing of welds
Contour and surface finish
Plug Weld, Diameter
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Plug Weld, Countersink
Plug Weld, Depth of Filling
Complete fill
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Plug Weld, Spacing
Plug Weld, Symbols
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Safety Considerations
Pressurized Gases
High temperatures and hot surfaces
Electrical hazards
Fume generation
Non-ionizing radiation
Ionizing radiation
Molten droplets of metal
Explosive hazards
Oxy-Fuel Cutting
Torch tip selection
Oxygen pressure
Acetylene pressure
Cutting Speed
Tip alignment
Torch Position
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Tip Alignment
Torch Position
Tilted to 20 degrees away from direction of cutting
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Torch Position
Torch 90 degrees to the surface of the metal
Torch Position
Cutting thin steel
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Cutting Conditions
Good Cut
Cutting Conditions
Preheat flames too small
Cutting speed too slow
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Cutting Conditions
Preheat flame too long
Top surface melted over
Cutting edge irregular
Excess slag
Cutting Conditions
Oxygen pressure too low
Top edge melted
Travel speed too slow
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Cutting Conditions
Oxygen pressure too high
Nozzle too small
Cut control lost
Cutting Conditions
Cutting speed too slow
Irregular, emphasized drag lines
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Cutting Conditions
Cutting speed too fast
Pronounced break in drag line
Cut edge irregular
Cutting Conditions
Torch travel unsteady
Cut edge wavy and irregular
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Cutting Conditions
Cut lost
Not properly restarted
Bad gouges at restart point
Shielded Metal Arc Welding
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Shielded Metal Arc Welding
Acronyms:
AC Alternating Current
DC Direct Current
CC Constant Current
CV Constant Voltage
DCEN Direct Current Electrode Negative
DCEP Direct Current Electrode Positive
OCV Open Circuit Voltage
Current and Polarity
DCEN DCEP
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Current and Polarity
DCEP Deeper penetration than DCEN
DCEN Electrode melts faster, less heat to the
base metal
Used for welding thin materials
AC Produce a neutral or reducing gas
(to protect the weld puddle)
Medium depth of penetration
Current and Polarity
Manual processes such as SMAW require CC welding
machine
CC machines sometimes called droopers or droop curve
machines
A CC machine adjusts to maintain a constant current as
small changes in arc length occur
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Constant Current Machine
25% change in voltage 4% change in current
Welding Machines
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Welding Machines
Current Type (AC, DC, or AC/DC)
Input power requirements (117, 240 0r 550 Volts)
Rated current output
Duty Cycle
Open Circuit Voltage
Rated Current Output
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Duty Cycle
How long a welding machine can be used at maximum
current
Based on a ten minute cycle
E.g. 60% duty cycle machine can be used at maximum current
for a maximum of 6 minutes out of every 10 minutes.
It can be used for longer periods at lower current settings
Duty Cycle
200 amp, 20% duty cycle
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Open Circuit Voltage
Voltage of the welding machine when on but not being used.
Typically 80 volts compared to closed circuit voltage of
5 to 30 volts
A high OCV is required to initiate the arc.
Welding Leads
Electrode lead
Work lead
Electrical resistance increases as diameter decreases
and length increases
Voltage and current are affected when leads are too small
in diameter
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Welding Leads
Welding Technology Fundamentals
Page 58
Wire Diameter
Suggested Filter Lenses
Sensible 7 thru 14 Shade
Adjustability On The Outside
Of The Helmet While You Are
Welding
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SMAW ElectrodesSpecified by:
AWS
A5.1 carbon steel
A5.3 aluminum and aluminum alloys
A5.4 corrosion resistant steels
A5.5 low alloy steels
A5.6 copper and copper alloys
A5.11 nickel and nickel alloys
A5.15 gray and ductile cast iron
CSA W 48-01
carbon steel covered electrodes
chromium and chromium-nickel covered electrodes
low alloy steel covered electrodes
Electrode Coverings
1. Add filler metal
2. Create a protective gas shield
3. Create a flux to remove impurities
4. Create slag to protect bead as it cools
5. Add alloys to improve mechanical and chemical properties
6. Determine the polarity of electrode
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Electrode Size
CSA W47-01
Electrode Size
AWS
Lengths: 9, 12, 14, and 18 inches
Diameters: 1/16, 5/64, 3/32, 1/8, 5/32, 3/16, 7/32,
1/4, 5/16, 3/8 inches
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Freezing Characteristics
Electrodes manufactured to melt rapidly are called
fast-fill electrodes
Electrodes manufactured to freeze rapidly are called
fast-freeze electrodes
Electrodes manufactured to compromise between
fast-fill and fast-freeze are called fill-freeze
Electrode Designations
E 6010
AWS
Electrode
Minimum tensile strength in thousand psi
Welding position
Utilization
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Minimum Tensile strength
Minimum tensile strength of the as deposited metal
Welding Position
1 All position
2 Flat and horizontal fillets only
3 Flat position only
4 Flat, horizontal, overhead and vertical down
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Team Assignment 5
Assignment
What electrodes are low hydrogen?
What electrodes cannot be used with AC?
Which electrodes have iron powder addition?
Cellulose is used to improve penetration, what
electrodes will provide good root penetration?
What electrodes cannot be used for DCEP?
Low Hydrogen Electrodes
*5, 6 & 8
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E 7018
E4918 (CSA W48-01)
Low hydrogen
Fill-freeze
All position
70,000 psi, 490 Mpa
Moderately heavy slag easy to remove
Smooth quiet arc, very low spatter, medium penetration
AC or DCEP
Iron powder addition
Electrodes
Assignment: Prepare a similar description for E7015,
E7016, E7028, E8018, E6010, E6019
Hint: Use references: Welding Technology Fundamentals,
Page 74-78, Procedure Handbook of Arc Welding
Chapter 6.2, and CSA W48-01 appendix D
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Electrode Storage
Low Alloy
Steel
Electrodes
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Electrode Designations
E 10016-D2
AWS
Electrode
Minimum tensile strength in thousand psi
Welding position
Utilization
Alloy addition
Alloy Additions
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Low Alloy Electrodes
Assignment: 1. Describe the electrodes E9018-B3L and
E6218-B3L
2. Create memory rules to help recall which
electrodes are low hydrogen, and which electrodes
cannot be used with AC
Chromium and Chromium
Nickel Electrodes
E 316L-16
Alloy designation
ElectrodePosition
Use-ability
15 all position DC only
16 all position AC/DC, (DC if available)
25 flat or horizontal position only, DC
26 flat or horizontal position AC/DC (DC if available)
Low carbon
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Chromium and Chromium
Nickel Electrodes
Team Assignment 6:
1. What electrode is used to join 304 stainless steel
to 304 stainless steel?
2. What electrode is used to join 316L stainless steel
to 316L stainless steel?
3. What electrode is used to join 304L stainless steel
to 316L stainless steel?
Hint: Procedure handbook of Arc Welding chapter 7.2
Flat Welding PositionStriking an arc
Scratch method Pecking method
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Arc Blow
Stringer Bead
Width of bead 2 to 3 times electrode diameter
Height of bead 1/8th bead width
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Weaving Bead
Width less than 6 times
Travel Angle
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Work Angle
Reading The Bead
Good bead
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Reading The Bead
Current too low
Reading The Bead
Current too high
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Reading The Bead
Arc length too short
Reading The Bead
Arc length too long
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Reading The Bead
Travel speed too slow
Reading The Bead
Travel speed too fast
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Gas Tungsten Arc Welding
Current & Heat Distribution
Constant current
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Cleaning Action
Shielding Gases
Argon
Easier to start and maintain arc
Lower flow rates
Less expensive
Helium
Hotter arc
Deeper penetration
Faster welding speeds
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Electrodes
Zirconia: AC only, Aluminum
Thoria: Steel and SS
Pure: Aluminum
Current Selection
R2 p9.4-2
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Current Selection
Current Selection
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Pulsed GTAW
Arc Starting
High frequency start
Electrode contact
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Laying A Bead
Pool formed Electrode moved to
back of puddle, filler
added to front of
puddle
Rod is withdrawn
electrode is moved
to front of puddle
Typical SS Welding Procedures
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GTAW Variations
Autogenous
Automatic
Hot Wire
Multi-Electrode
Team Assignment 7
Prepare a welding procedure including all the details your
team is capable of to perform a full penetration Butt weld
to join two 3-1/2” schedule 40, 316L pipe for use in a
pressure chemical application.
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Gas Metal Arc Welding
Metal Transfer
Short Circuit
Globular Transfer
Spray Transfer
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Short Circuit
Thin material
Out of position
Low heat transfer
Globular Transfer
Spatter, flat position
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Spray Transfer
At least 90% Argon
Pulsed Spray Transfer
Above and below transition current
Out of position
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Power Supply
Constant Potential
Inductance
Slope Adjustment
No current adjustment
Wire Feeder
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Shielding Gas
Type of transfer
Penetration and bead shape
Speed of Welding
Mechanical Properties of weld
Shielding Gas
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Shielding GasArgon: aluminum, nickel, copper magnesium
excellent arc stability
good penetration and bead profile
finger like penetration
CO2 steel
reactive gas
will not support spray transfer
greater spatter and fumes
good fusion and penetration
Helium heavy sections of Al, Cu and Mg
higher thermal conductivity
additional heat to base metal
Shielding GasArgon-Oxygen 1 to 8% Oxygen
Stainless steel
increases droplet rate
more fluid puddle
reduces undercut
Argon- CO2 Carbon and low alloy steels
Most popular 5 to 18%
More fluid puddle
Higher welding speeds
Argon- Helium Aluminum, copper, nickel alloys
Increased heat input
Deeper penetration
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Electrode Wire
ER49S-B2
Electrode
Rod
Solid
Alloy
Tensile Strength
[MPa]
Electrode Wire
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Torch Position
Torch Position
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Team Assignment 8
Flux Cored Arc Welding
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Flux Cored Arc Welding
Electrodes
1. Gas shielded
2. Self Shielded
3. Metal Cored
Gas Shielded Electrodes
Used with same equipment as GMAW
Constant voltage
Constant wire speed
Most are designed for DCEP
Gas is usually CO2 or 75% Ar / 25%CO2
Rutile wire: spray transfer only
stable arc, smooth bead
good penetration & out of position
Basic wire: short circuit and globular transfer
considerable spatter
not easy to use out of position
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Self Shielded Electrodes
Very similar to an inside out SMAW electrode
Flat and out of position wire
Immune to moisture pickup
DCEN or DECP, with long stick-out
Most fume generation
Metal Cored Electrodes
Core contains: arc stabilizers
deoxidizers
metal powders
Used with shielding gas
Short circuit/globular/spray transfer
Out of position with pulsed spray transfer
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Electrode Designations
EXXXT-1
Electrode
Tensile Strength
Tubular or C = metal cored
Grouping (27 groups /
CSA W48-01)
Welding Position
1= all, 2 = F groove and F&H fillet
Refer to CSA W48-01 figure B1
Power Supply
Constant Potential
Inductance
Slope Adjustment
No current adjustment
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Submerged Arc Welding
Three to ten times faster than SMAW
Electrodes
Typical wire size: 1/16, 5/64, 3/32”
Also cored and strip
Available for mild steel, low alloy, stainless steel and
nickel-base alloys
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Fluxes
Manufacturing: Fused (mixed, melted, fused, crushed,
screened & packaged)
Bonded (blended dry, binder added,
dried, sized & packaged)
Alloy Content
of Weld: Active (Controlled amounts of Mn & or Si
to improve resistance to porosity
and cracking)
Neutral (contains little or no deoxidizers)
Power Supplies
DCEN, DCEP, AC
DCEP recommended for deep penetration
DCEN recommended for: fillets (clean plate)
hard facing
hard to weld steels
greater build-up
AC recommended for: tandem arc
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Joint Preparation
Joint Preparation
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Joint Preparation
Backing Required
Electrode & Flux Specification
F XX X X-E L XX X
Flux
Tensile StrengthHeat Treat Condition
A = as welded, P = PWHT
Temp of impact strength
Z = impact testing not required
S = single pass only
Electrode
Mn L = low, M = medium,
H = high, C = composite electrode
If solid K = killed steel
Carbon or chemical analysis
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Team Assignment 9
Make a short presentation (7 to 10 minutes) to act as a
review for your class mates on one of the welding methods.
SMAW
GTAW
GMAW
FCAW
SAW
Heating
Preheating: Just prior to welding
Interpass heating During welding
Post weld heat treatment : After welding
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Preheating
Why?
Reduce local shrinkage stresses
Reduce cooling rate through critical temperature
(870º to 720º C) to prevent excess hardening
& lowering ductility in weld & HAZ
Reduce cooling rate around 205º C to allow more
time for hydrogen to to diffuse from weld
and adjacent plate material to avoid hydrogen
embrittlement and cracking
How Much Preheat?
Base metal chemistry
Plate thickness
Restraint
Rigidity of members
Heat input of welding process
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Guides for Preheat
Specification
Note usually given as minimum preheat and is
determined by measuring temperature for some
distance around the weld
Observe minimum ambient temperatures
Remember Q&T steels can be damaged if preheat
is to high
Guides for Preheat
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W59-03 Appendix P
W59-03 Appendix P
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W59-03 Appendix P
W59-03 Appendix P
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W59-03 Appendix P
Methods of Preheating
Production of small parts maybe best in a furnace
Natural gas premixed with air
Acetylene or propane torches
Electric strip heaters parallel to joint
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Measuring Preheat
Temperature
With the exception of Q&T steels temperatures
can be exceeded by 40º C
If temperature indicating crayons are used it is best
to have one above and one below target temperature
Pyrometers, thermocouples and infrared sensors are also
Used, calibration and proper use are important
Preheating Quench &
Tempered Steel
Q & T steel have been heat treated heating above a
certain temperature will destroy the properties of that
heat treatment
The assembly may require preheat but it must not be to high
The material must cool rapidly enough to re-establish the
original properties
Preheating and welding heat input must be closely controlled
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Interpass Temperatures
Usually steel which requires preheat is required to
remain at that temperature between passes
On massive weldments the heat input from welding
may not be sufficient to maintain the required temperature
Just as it is desirable to control the cooling rate of the weld
as a whole it is also important to control cooling between
passes
Heat from additional sources maybe required to maintain
interpass temperatures
Post Weld Heat Treatment
Annealing
Normalizing
Stress Relief
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Full Annealing
Purpose:
Make steel soft and ductile
Reduce stresses
Heat steel to 100º F above critical temperature
Hold for 1 hour per inch of thickness
Slow cool, usually in furnace
Normalizing
Purpose:
Reduce stresses, usually after welding
Greater hardness & tensile strength than
full annealing
Heat steel to 100º F above critical temperature
Hold for 1 hour per inch of thickness
Cool in still air
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Stress Relief
Purpose:
Provides dimensional stability
Softens martensitic areas
Improves fracture resistance
Heat slowly to about 625º C
Hold for a period of time
Slowly cool
Welding Procedures
CWB Pre-qualified Joints
Not pre-qualified Joints
ASME No pre-qualified joints
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CWB Pre-Qualified Joints
CSA W59-03 Section 10
SMAW, FCAW and SAW only
Weld Procedure Specification
Submit to CWB for Approval
Qualify Welders
CWB Not Pre-Qualified Joints
Welding Procedure Specification
Procedure Qualification
CWB Approval
Qualify Welders
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ASME Weld Procedures
No pre-approved joints
Each welding procedure will have a procedure
qualification record
Three types of variables: Essential
Supplementary
Non-essential
What is Included in a Welding
Procedure?
One welding procedure specification
One or more data sheets
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Welding Procedure
SpecificationScope
Welding Procedure
Base Metal
Base Metal Thickness
Preparation of Base Material
Filler Material
Shielding Gas
Position
Minimum Preheat and Interpass Temperatures
Electrical Characteristics
Welding Technique
Treatment of Underside of Groove
Weld Metal Cleaning
Quality of Welds
Storage of Electrodes
Data Sheet
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Data Sheet
CWB Welder Qualification
Classification
Process
Mode of Application
Position
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Classification
S With backing
T Without backing
FW = fillet & tack welds, ASW = arc spot weld, WT = tack welds
Process
SMAW
FCAW
GMAW
SAW
ESW
EGW
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Mode of Application
Manual
Semi-automatic
Machine Welding
Automatic
Position
Class F Flat position & horizontal fillets
Class H Flat and horizontal positions
Class V Flat, horizontal & vertical positions
Class O Flat, horizontal, vertical & overhead positions
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Electrode Designations
F4 Exx15, Exx16, Exx18
F3 Exx00, Exx10, Exx11
F2 Exx12, Exx13, Exx14
F1 Exx22, Exx24, Exx27, Exx28
Team Assignment 10
Review a weld procedure and present your teams
understanding to your class
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Verification Functions
Develop inspection plans & check lists
Ordering and delivery of material
Welding procedure specifications
Welder qualifications
Proper fit up and welding processes
Heat Treatment
Inspection
Inspection Records
Nondestructive Testing
Procurement Verification
Vendor approval
Quantity & Dimensions
Material Specification
Special Requirements
Heat treatment
Inspection
Nondestructive Testing
QA Requirements
Documentation Requirements
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Receiving Inspections
Quantity Inspections
Dimensions
Identification
Mill test reports or other required documentation
Manufacturing defects
Weather or transportation damage
Documentation Verification
Mill Test Reports
Certificates of Compliance
Partial Data Reports
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SMAW Electrode Storage
Low Hydrogen Minimum 120º C
Used within 4 hours
Alternate exposure times maybe approved
Portable storage devices maybe approved
E49 within 10 hours in portable storage
Non-Low Hydrogen Stored warm and dry
Kept free from oil and grease
Preparation for Welding
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Preparation for Welding
Assembly Fillet Welds
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Assembly Groove Welds
Workmanship
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Tack Welds
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Backing
Distortion Control
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Preheat & Interpass
Temperatures
Dimensional Tolerances
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Sweep
Camber
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Warpage and Tilt
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Misalignment
Profile of a Fillet Weld
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Fillet Weld Size
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Fillet Weld Size
Butt Weld Profile
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Groove Weld Profile
Butt Weld Profile
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Butt Weld Profile
Undercut
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Butt Weld Profile
Weld Discontinuities
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Incomplete Penetration
Lack of Fusion
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Porosity
Slag
Inclusions
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Solidification
Crack
Hydrogen Induced Cracking
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Lamellar Tearing
Arc Strikes
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Excess Convexity
Excessive Concavity
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Excessive Reinforcement
Insufficient Reinforcement
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Undercut
Discontinuities Related to
Specific Welding Methods
SMAW
SAW
GMAW & FCAW
GTAW
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SMAW
Spatter Lower current
Check polarity
Shorter arc
If molten metal running in front of arc,
change electrode angle
Watch for arc blow
Ensure electrodes are not wet
SMAW
Undercut Reduce current
Reduce travel speed
Reduce electrode size
Change electrode angle
Avoid excessive weaving
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SMAW
Rough Welding Check polarity
Check current
Ensure electrodes are not wet
SMAW
Porosity Remove scale rust and moisture
Use low hydrogen electrodes
Use shorter arc length
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SMAW
Lack of Fusion Increase current
Stringer bead technique
Ensure joint is clean
Check joint fit-up and design
Over Lap
SMAW
Incomplete Penetration Increase current
Decrease travel speed
Use smaller diameter electrode
Increase root gap
Proper electrode selection
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SMAW
Cracking Hydrogen induced cracking
Low hydrogen electrodes
Store electrodes properly
Use preheat
Smaller diameter electrodes
SMAW
Cracking Hot Cracking
Proper fit-up
Proper electrode selection
Ensure root pass is of sufficient size
Check rigidity of joint
Check Distortion control techniques
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SMAW
Cracking Solidification Cracking
If originating in crater use back
step technique
If centre bead decrease travel speed
SAW
Cracking Fillet Welds
If members 25 mm or greater ensure
gap of 1 to 1.5 mm to help with
shrinkage
Check polarity, usually DCEP but
DCEN sometimes used to
reduce penetration to help
deal with cracking
Check wire size, larger wire often used
when cracking is a problem
Check condition of root pass and fit-up
Check bead shape (1-1/4 to 1)
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SAW
Cracking Fillet Welds & T Welds
Groove angles should be at least 60º
If different materials, weld puddle
towards the most weld-able material
Increasing stick out reduces cracking
tendency
Ground at the start end of the weld
Decreasing welding speed and
current reduces cracking tendency
SAWCracking Butt Welds
If bead is hat shaped , check voltage
and travel speed, may need to be
reduced
If the first bead from the second side,
after back gouging is cracking check
to make sure the width is greater than
depth
If the steels are of poor weld-ability
often reducing current and/or travel
speed or increasing stick out reduces
dilution and reduces cracking tendency
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GMAW & FCAW
Fillet Welds Undercut & overlap are common
Check manipulation of the gun to ensure
welding of both base metals
Slag
Check for slag removal between passes
Gas Shielding is affected by ambient air movement
GTAW
Porosity Check shielding gas flow rates, leaks etc.
Check arc length (too long cannot be protected)
Tungsten Inclusions
Check for touching the electrode into the puddle
Check for current being to high
Check the size and type of electrode
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Team Assignment 11
Identify weld discontinuities in samples provided.
Record results
Mechanical Testing
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Bend Tests
Face Bend Root Bend
Bend Tests
Root Bend Face Bend
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Bend Tests
Bend Tests
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All Weld Metal Tensile Test
Reduced Section Tensile Test
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Vickers Hardness Test
Vickers Hardness Test
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Hardness Tests
Three groups:
Elastic hardness
Resistance to cutting or abrasion
Resistance to penetration
Resistance to Penetration
Brinell Hardness Test
A hard steel ball or carbide sphere is
forced into the surface under a specified
load.
Diameter is measured to determine Brinell
Hardness
BHN = Brinell Hardness Number
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Resistance to Penetration
Rockwell Hardness Method
Measures the net increase in depth of the
impression after a minor load is applied
and after the major load is applied
14 different scales
C, A & D are the most common scales
15-N, 30-N & 45-N are the most common
Superficial scales
Resistance to PenetrationVickers Hardness Test
Considered a micro hardness method
Uses a square based diamond pyramid
The surface dimensions of the indent are
measured and converted to hardness
Used for measuring case hardening and
heat affected zones of welds
VHN = Vickers Hardness Number
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Resistance to Penetration
Tukon Hardness Method
Micro hardness technique
Employs a diamond indenter
Usually combined with a Vickers unit
Resistance to Penetration
Knoop Hardness Method
Micro hardness technique
KHN = Knoop Hardness Number
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Impact Tests
Measures the decrease in
fracture resistance caused by
sudden loading in the
presence of a notch
Methods:
Charpy
Izod
Units: foot pounds of joules
Charpy Impact Tests
CVN = Charpy V-Notch
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Izod Impact Tests
Transition Temperature
Impact test results must include temperature
Most materials exhibit a change from notch tough to notch
brittle over a very narrow temperature range called the
transition temperature
Transition temperature is determined by conducting impact
tests at different temperatures until an abrupt change in
energy required to break the specimen is noted