Fusion Welding
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Welding Glossary
If you are unfamiliar with welding, the following site is an
excellent glossary of welding terms.
http://www.hobartwelders.com/elearning/glossary.php
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Definition
• Fusion welding is a group of processes
that bond metal together by heating a
portion of each piece above the melting
point and causing them to flow together.
• Usually includes the uses a filler material
to insure the joint is filled.
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Fusion Welding Process
Learning the basics
1. “Welding and cutting requires
good eye-mind-hand
coordination.”
2. Must be able to concentrate.
3. Must see and understand the
activity in the molten metal as
the process is occurring.
4. Thorough understanding of the
operation of the equipment.
5. Must have good depth
perception.
6. Must be able to determine the
time and place to apply heat
and/or filler metal.
7. Maintain a good body position so
it is possible to look left and right,
and ahead and behind the puddle.
8. Must know the quality standards.
9. Must understand the procedures
for inspecting work.
10. Must learn safe work habits.
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Fusion Welding Requirements
All fusion welding processes have four requirements.




Heat
Shielding
Filler material
Critical distance
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Fusion Welding--Heat
 Sufficient heat must be applied to the weld zone to raise the
temperature above the melting point.
 Melting point is different for each material.
Material
Melting Point (oF)
Material
Melting Point (oF)
Tin
450
Steel (HC)
2,500
Lead
620
Stainless Steel
2,550
Zinc
786
Steel (MC)
2,600
Aluminum
1,220
Steel (LC)
2,700
Silver
1,760
Iron
2,800
Copper
1,980
Chromium
3,000
Cast Iron
2,300
Titanium
3,260
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Fusion Welding—Heat—cont.
Two important principles
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2
A metal with higher melting temperature will require more heat to
fusion weld than a metal with a lower melting temperature.
The larger the mass of metal, the greater the amount of heat that
will be required to raise the temperature above the melting point.
Conclusion: you must be able to adjust the heat produced to match the
needs of the weld.
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Fusion Welding—Heat--cont.
To be able to adjust the heat, you must know the
source of the heat.
The source of the heat is one of the distinguishing
characteristics between the welding process.
 SMAW
Electric arc
 GMAW
Electric arc
 FCAW
Electric arc
 GTAW
Electric arc
 OFW
Gas Flame
How is the heat produced adjusted for each fusion welding
process?
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Fusion Welding--Shielding
 Steel is produced in an environment devoid of atmospheric air.
 If atmospheric air is allowed to mix with the molten metal during the
fusion welding process the quality of the weld is reduced.
 The method used for shielding is another difference between the
common welding processes.
 SMAW
Inert gas from flux
 GMAW
Inert gas from cylinder
 FCAW
Inert gas from flux
 GTAW
Inert gas from cylinder
 OFW
Gas Flame
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Fusion Welding--Filler Material
 If filler material is not added during a fusion welding process the joint
will be starved.
 Starved joints have reduced strength.
 For this reason, joints are usually
slightly over filled (reinforced) to
insure the strength is not
reduced.
 Reinforcement does not increase
the strength of the weld, just
insures the joint is not starved.
 Excessive reinforcement is wasted resources.
 Excessive reinforcement may need to be removed = additional cost..
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Fusion Welding--Filler Material--cont.
 The source of the filler material is also one of the differences
between the different welding processes.
 SMAW
Consumable electrode
 GMAW
Continuous wire electrode
 FCAW
Continuous wire electrode
 GTAW
Manual rod
 OFW
Manual rod
How is the rate of filler material delivery changed for each
process?
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Fusion Welding—Critical Distance
 Each fusion welding process has a critical distance that must be
maintained.
 Failure to maintain the critical distance can reduce the quality of
the weld and/or damage equipment.
 Critical distances:
SMAW
Arc length
GMAW
Stick out
FCAW
Stick out
GTAW
Arc length
OFW
Tip clearance
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Four Requirements Summary
To be able to fusion weld you must be able to set the machine for the
correct heat, insure the weld pool is adequately shielded, control the rate
of delivery of the filler material and maintain the critical distance.
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Fusion Welding’s Five (5) Factors Which
Determine The Quality Of The Weld
Angle
Manipulation
Heat
Speed
Distance
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Heat
Are temperature and heat the same?
What units are used to measure temperature?
What units are used to measure heat?
What determines the amount of heat that will be required to
complete a weld?
In fusion welding processes, the amount of heat must be
sufficient to raise the temperature of the metal above the
melting point.
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Heat—cont.
Six (6) ways of controlling welding heat
2. Equipment settings
1. Equipment size
3. Distance from heat source to work
4. The Manipulation of the heat source
5. Heat source angle
6. The travel speed
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Heat—Equipment Size
 In all fusion welding processes the effective heat at the weld is
influenced by the size of the components being used.
 SMAW
Electrode diameter
 GMAW
Wire diameter
 FCAW
Wire diameter
 GTAW
Filler rod diameter, tungsten electrode diameter
 OFW
Filler rod diameter, tip size
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Heat—Equipment Setting
 In all fusion welding processes the effective heat at the weld is
influenced by the settings on the equipment.
 SMAW
Amperage
 GMAW
Voltage, wire speed
 FCAW
Voltage, wire speed
 GTAW
Amperage, polarity
 OFW
Torch, regulators
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Heat--Distance
All welding and cutting processes have a critical distance.
The critical distance varies with each welding process.
Process
Distance
Identification
OFW
inner cone to work
Torch gap
SMAW
electrode end to work
Arc length
GMAW
contact tube to work
Stick out
FCAW
contact tube to work
Stick out
GTAW
end of tungsten to work
Arc length
The quality of fusion welds will be reduced if the critical distance is
varied beyond the recommended limits.
What are the results of insufficient or excessive distance for each
process?
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Heat--Manipulation
 You must insure manipulation is
necessary to produce the desired
weld.
 Manipulation (movement) is used to:
1. Control puddle in vertical,
horizontal and overhead welds.
2. Fill joint
3. Produce desired appearance
Some outcomes of improper
manipulation
1.
Reduced depth of fusion.
2.
Undercutting
3.
Porosity
4.
Slag inclusions
5.
Unnecessary wear on
joins of fingers and wrist.
Two points to remember
1.
Make sure there is a sound reason for the manipulation.
2.
Select a manipulation pattern that will produce the desired results.
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Heat--Angle
• Two angles are important in fusion welding
 work
 travel
The ideal angle is different for each type of weld, welding position
and welding process.
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Heat--Speed
 The ideal travel speed is different for each
weld, weld position and welding process.
 Operator must watch the welding process
and adjust speed as needed.
Speed indicators are:
A.
Size of bead
B.
Shape of ripples
C.
Depth of penetration
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Types of Welds
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Five Types of Welds
 Surface
 Groove
 Fillet
 Plug
 Slot
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Surface Welds
Surface welds are welds were material has been
applied too and/or blended with the surface of the
work piece.
Two common applications are for hard
surfacing and padding.
Surface weld nomenclature
A: Electrode wire
B: Electrode flux
C: Arc
D: Weld puddle
E: Bead
F: Slag
G: Gas shield
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Groove Welds
Groove welds are used to fuse the sides or
ends of two pieces of metal.
The primary use of groove welds is to complete
butt joints.
Groove weld nomenclature
A: Toe
B: Width
C: Face reinforcement
D: Toe
E: Joint preparation
F: Joint gap
G: Root reinforcement
H: Joint face
I: Base metal
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Fillet Welds
 Fillet welds have a triangular
cross section and are used to
fuse two faces of metal that
are at a 90 degree angle to
each other.
 Three common types are:
T
Lap
Corner
Fillet weld nomenclature
A: Reinforcement
B: Toe
C: Face
D: Throat
E: Toe
F: Leg
G: Root
H: Base metal
I: Leg
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Plug Welds
Plug welds are used to attach
two surfaces together when a
complete joint is not required
and the design does not allow
for any weld bead outside the
dimensions of the metal.
The holes can be made with a drill bit.
The weld is completed by establishing the arc on the bottom plate and
then continuing to weld until the hole is full.
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Slot Welds
Slot welds are identical to plug welds except for the shape of the
holes.
For slot welds, slots are machined or stamped in the upper plate.
They are completed the same as
plug welds.
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Five Types of Joints
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Five Types of Joints
Corner
Butt
Lap
T
Edge
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Butt Joints
 Used to attach two metal faces together.
 Joint can be completed with the faces square or beveled.
 How do you determine if you need to bevel a butt joint?
 What type of weld is used to complete a butt joint?
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Butt Joint--Multipass
Three examples for 1/8 inch SMAW electrode:
1/4 inch and less; single pass,
single side.
1/4 inch to 3/8’s inch; single pass, two
sides or joint prep and one side.
3/8’s inch to 3/4 inch; joint prep
and multiple pass.
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Corner Joints
 Three common types:
Joint
Weld
 Closed
Groove weld
 Partially open
Fillet weld
 Fully open
Fillet weld
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Lap Joints
 Lap joints are use to attach
metal that overlaps.
 A lap of three times metal
thickness provides maximum
strength.
 Welding both sides increases
strength in both directions.
What type of weld is used to complete a lap joint?
When would a multiple pass lap joint be made?
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Edge Joints
 Used to weld two surfaces
at 180 degrees.
 What type of weld is used
to complete an edge joint?
 When would a multipass
weld be used to complete
an edge joint?
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Five Welding Positions
Flat
Horizontal
Vertical down
Vertical up
Overhead
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Questions
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