part. Before assembly, the outer part is heated until it
expands enough to slide over the inner part. As the part
cools, it shrinks and locks the two pieces together.
Corner Joints and Welds
Corner joints are similar to T-joints, since they
consist of sheets or plates mating at an angle to one
another. They are usually used in conjunction with
groove welds and fillet welds. Some of the many
different corner weld designs are shown in Figure 6-33.
When using thinner gauges of metal, it may be difficult
to assemble component parts without proper tooling.
Tack welding and welding often will cause distortion and
buckling of thinner materials. For the most part, use of
corner joints should be limited to heavier materials in
structural assemblies.
Edge Joints and Welds
Edge welds are used where the edges of two sheets
or plates are adjacent and are in approximately parallel
planes at the point of welding. Figure 6-34 shows several
types of edge weld designs. These designs are common
only in structural use. Since the weld does not penetrate
completely through the joint thickness, it should not be
used in stress or pressure applications.
Special Designs and Procedures
Special designs are often used in the fabrication of a
weldment where:
• Welds cannot be thermally treated after welding
because of configuration or size. Material is added
to the joint thickness, as shown in Figure 6-35, and
the weld is made restricting the heat flow into the
thinner metal. This type of joint will achieve the
full mechanical values of the base material.
• Joining of dissimilar materials can be done by
buttering the face of one material to match the
other, as shown in Figure 6-36.
Special procedures and tooling may be used to
provide a preheating, interpass, and postheating opera-
tion to control grain size. Preheating is generally used to
slow down the cooling rate of the weld to prevent
cracking. Interpass temperature is the Min/Max temper-
ature at which a weld can be made on a multi-pass weld.
Individual chapters regarding the welding of various
metals will define the requirements for preheating, inter-
pass, and postheating temperatures. These temperatures
may be checked by the use of special crayons, paints, or
pellets like those in Figure 6-37.
Special procedures, tooling, and chill bars may be
used to localize and remove welding heat during the
welding application. Figure 6-38 shows an application of
tooling used to remove heat from the part.
Chapter 6 Weld Joints and Weld Types 67
Edge to edge
Flush corner
Half overlap
Figure 6-33. Common corner weld joint designs that may be
used in fabrication.
Figure 6-34. Common edge weld joint designs that may be
used in fabrication.