Resistance and Solid-State Welding
Processes
Chapter 32
ME-215 Engineering Materials and Processes
Veljko Samardzic
32.1 Introduction
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32.2 Theory of Resistance
Welding
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Basic Resistive Welding
FIGURE 32-1 The basic resistance welding circuit.
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Resistive Welding Temperature
Distribution
FIGURE 32-2 The desired
temperature distribution across
the electrodes and workpieces
during resistance welding.
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Current and Pressure for Resistive
Welding
FIGURE 32-3 A typical current and pressure cycle for resistance welding. This
cycle includes forging and postheating operations.
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Schematic of Resistive Welding
FIGURE 32-4 The
arrangement of the electrodes
and workpieces in resistance
spot welding.
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32.3 Resistance Welding
Processes
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Microstructure of a Resistance
Weld
FIGURE 32-5 A spot-weld nugget between two sheets of 1.3-mm (0.05-in.)
aluminum alloy. The nugget is not symmetrical because the radius of the
upper electrode is greater than that of the lower electrode. (Courtesy
Lockheed Martin Corporation, Bethesda, MD.)
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Tear Test
FIGURE 32-6 Tear test
of a satisfactory spot
weld, showing how
failure occurs outside of
the weld.
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Resistive Welder
FIGURE 32-7 Single-phase,
air-operated, press-type
resistance welder with
microprocessor control.
(Courtesy Sciaky Inc., Chicago, IL.)
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Spot Welding Application
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Spot Welding Seams
FIGURE 32-8 Seam welds
made with overlapping spots
of varied spacing. (Courtesy
Taylor-Winfield Corporation,
Brookfield, OH.)
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Schematic of Seam Welding
FIGURE 32-9 Schematic
representation of the
seam-welding process.
those
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Tube Welding
FIGURE 32-10 Using high- Squeeze roll
frequency AC current to produce
a resistance seam weld in buttwelded
tubing. Arrows from the
contacts indicate the path of the
high-frequency current
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Projection Welding
FIGURE 32-11 Principle of
projection welding (a) prior to
application of current and
pressure and (b) after formation
of the welds.
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32.4 Advantages and Limitations of
Resistance Welding
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32.5 Solid-State Welding
Processes
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Process Summary for RW
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Cold Welding
FIGURE 32-12 Small
parts joined by cold
welding. (Courtesy of
Koldweld Corporation,
Willoughby, OH.)
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Roll Welding
FIGURE 32-13 Examples of
roll-bonded refrigerator freezer
evaporators. Note the raised
channels that have been
formed between the roll-bonded
sheets. (Courtesy Olin Brass,
East Alton, IL.)
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Friction Welding
FIGURE 32-14 Sequence for making a friction weld. (a) Components with square surfaces are inserted
into a machine where one part is rotated and the other is held stationary. (b) The components are
pushed together with a low axial pressure to clean and prepare the surfaces. (c) The pressure is
increased, causing an increase in temperature, softening, and possibly some melting. (d) Rotation is
stopped and the pressure is increased rapidly, creating a forged joint with external flash.
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Schematic for Friction Welding
FIGURE 32-15 Schematic diagram of the equipment
used for friction welding. (Courtesy of Materials
Engineering.)
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Inertia Welding
FIGURE 32-16 Schematic
representation of the various
steps in inertia welding. The
rotating part is now attached
to a large flywheel.
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Examples of Friction Welding
FIGURE 32-17 Some typical
friction-welded parts. (Top)
Impeller made by joining a
chrome–moly steel shaft to a
nickel–steel casting. (Center)
Stud plate with two mild steel
studs joined to a square plate.
(Bottom) Tube component
where a turned segment is
joined to medium-carbon steel
tubing. (Courtesy of Newcor Bay
City, Division of Newcor, Inc.,
Royal Oak, MI.)
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Stir Welding
FIGURE 32-18 Schematic
of the friction-stir welding
process. The rotating probe
generates frictional heat,
while the shoulder provides
additional friction heating
and prevents expulsion
of the softened material
from the joint. (Note: To
provide additional forging
action and confine the
softened material, the tool
may be tilted so the
trailing edge is lower than
the leading segment.)
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Example of Stir Welding
FIGURE 32-19 (a) Top surface
of a friction-stir weld joining 1.5mm- and 1.65-mm-thick
aluminum sheets with 1500-rpm
pin rotation. The welding tool
has traversed left-to-right and
has retracted at the right of the
photo. (b) Metallurgical cross
section through an alloy 356
aluminum casting that has been
modified by friction-stir
processing.
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Features of Stir Welding
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Schematic of Ultrasonic Welding
FIGURE 32-20 Diagram of the
equipment used in ultrasonic
welding
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Application of Ultrasonic
Welding
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Explosive Welding
FIGURE 32-21 (Left) Schematic of the explosive welding process. (Right)
Explosive weld between mild steel and stainless steel, showing the characteristic
wavy interface.
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Veljko Samardzic