Flux Cored Arc Welding Handbook, 3rd Edition Page 58 (58 of 177)

Special Designs and Procedures
Special designs are used in the fabrication of a weld-
ment when:
• Welds cannot be thermally treated due to their
configuration or size. Additional material is
added to the joint thickness, and the weld is made
restricting the heat flow into the thinner material.
See Figure 6-34. This type of joint will achieve
the full mechanical values of the base material.
• Joining dissimilar metals often requires buttering
one material to allow the joint to be welded with
a common filler material. See Figure 6-35.
• Tooling can be used to preheat component parts
and maintain interpass temperatures. Preheating
slows the cooling rate of the weld to prevent
cracking of sensitive components. Interpass
temperature is the maximum temperature
allowed when the next pass is started on a
multipass weld. Postheating is used to con-
trol grain size, prevent cracking, and remove
residual stresses. These temperatures may
be checked using special crayons, paints, or
pellets, Figure 6-36.
• Chill (backing) bars and tooling may be used to
localize and remove heat during the welding
application. See Figure 6-37. Other benefits of
tooling include:
• Aligning components before and during the
welding operation.
• Checking component parts for proper fitup.
• Preventing excessive drop-through penetration
on the other side of the weld.
58 Flux Cored Arc Welding Handbook
Figure 6-33. Common edge-joint designs.
Figure 6-34. Joint thickness and filler material tensile strength
combined are equivalent to the strength of the base material.
Heat affected zone
within this area
Wall
thickness
Reinforcement
Figure 6-35. Buttering is commonly used to adapt dissimilar
metals for welding.
New
weld
Original
material
Buttered
weld
Original
material
Buttered
weld

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Extracted Text (may have errors)

Special Designs and Procedures
Special designs are used in the fabrication of a weld-
ment when:
• Welds cannot be thermally treated due to their
configuration or size. Additional material is
added to the joint thickness, and the weld is made
restricting the heat flow into the thinner material.
See Figure 6-34. This type of joint will achieve
the full mechanical values of the base material.
• Joining dissimilar metals often requires buttering
one material to allow the joint to be welded with
a common filler material. See Figure 6-35.
• Tooling can be used to preheat component parts
and maintain interpass temperatures. Preheating
slows the cooling rate of the weld to prevent
cracking of sensitive components. Interpass
temperature is the maximum temperature
allowed when the next pass is started on a
multipass weld. Postheating is used to con-
trol grain size, prevent cracking, and remove
residual stresses. These temperatures may
be checked using special crayons, paints, or
pellets, Figure 6-36.
• Chill (backing) bars and tooling may be used to
localize and remove heat during the welding
application. See Figure 6-37. Other benefits of
tooling include:
• Aligning components before and during the
welding operation.
• Checking component parts for proper fitup.
• Preventing excessive drop-through penetration
on the other side of the weld.
58 Flux Cored Arc Welding Handbook
Figure 6-33. Common edge-joint designs.
Figure 6-34. Joint thickness and filler material tensile strength
combined are equivalent to the strength of the base material.
Heat affected zone
within this area
Wall
thickness
Reinforcement
Figure 6-35. Buttering is commonly used to adapt dissimilar
metals for welding.
New
weld
Original
material
Buttered
weld
Original
material
Buttered
weld

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groove-and-fillet welds, Figure 6-30. Fillet weld sizes
must conform to allowable design loads. AWS specifies
where fillet welds may be used, as well as the minimum
and maximum sizes permissible in the construction of
buildings and bridges. When welding on materials less
than 1/4″ thick, and design loads are unknown, follow
this rule of thumb: the fillet weld lengths must equal
the thickness of the thinner material being joined. See
Figure 6-31.
The main problem in making fillet welds is lack of
penetration at the joint intersection. To prevent this con-
dition, make stringer beads (welds made without side-to-
side motion) at the intersection. Weave beads across the
intersection are prone to lack of penetration.
Corner Joints and Welds
Corner joints are similar to T-joints. They consist of
sheets or plates mating at an angle to one another,
Figure 6-32. Corner joints are usually used in conjunc-
tion with groove welds and fillet welds. When using thin
materials, the assembly of component parts may be diffi-
cult without proper tooling. Tack welding and welding
without extensive tooling often causes distortion and
buckling of thinner materials. For the most part, these
types of joints should be limited to heavier materials in
structural assemblies.
Edge Joints and Welds
Edge welds are used when the edges of two sheets
or plates are adjacent and have approximately parallel
planes at the point of welding. See Figure 6-33. Edge
welds are applicable on thinner gauges of metal and
are not used in structural assemblies. Only full pene-
tration welds should be used with stress or pressure
applications.
Chapter 6 Weld Joints and Weld Types 57
Figure 6-30. Types of T-joints and welds.
Groove-and-fillet combination Double fillet Single fillet
Figure 6-31. Fillet weld legs should be equal in length from the
root of the joint. Unequal leg length, unless specified, will not
carry the designed load and may fail when stressed.
Leg length
Size of
required
weld
Figure 6-32. Common corner-joint designs used in the fabrication of component parts.
Flush corner Half overlap Edge-to-edge

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Review Questions
Please do not write in this text. Write your answers on a
separate sheet of paper.
1. Name the five basic types of weld joints.
2. Identify the type of joint and the type of weld shown
for each figure.
3. Which does not characterize double-groove welds?
A. Less distortion of the weldment.
B. Less metal used.
C. Higher cost.
D. 100% penetration.
4. Fillet welds made from each side of the joint may be
(smaller, larger) than those made from one side of
the joint.
5. What type of joint is used in the auto industry for
overlapping sheet metal pieces with a spot or plug
weld?
6. In what weld configuration are lands used at the bot-
tom of the joint for butt welding pipes together to
minimize shrinkage?
7. Prefabricated _____ are used in butt welds to assem-
ble the parts and minimize burn-through.
8. On welding drawings, the symbol below the refer-
ence line indicates the weld is to be made on the
_____ of the joint. The symbol above the reference
line indicates the weld is to be made on the _____ of
the joint.
9. Identify the weld symbols shown.
Chapter 6 Weld Joints and Weld Types 59
Figure 6-36. Temperature crayons and pellets can be used to
determine preheat and postheat temperatures.
Figure 6-37. Tooling and chill bars are used to remove heat
from the weld and resist heat flow into the base material.
Hold-down and chill bars
Backing and
chill bar
A. B. C. D.
E. F. G.
A. B. C.
D. E.

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