Resistance and Solid-State Welding Processes

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Resistance and Solid-State Welding Processes

• Chapter 32

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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 chromemoly
steel shaft to a nickelsteel 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 1.5- mm- 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.