Chapter 32:

Resistance and Solid-State

Welding Processes

DeGarmo’s Materials and Processes in

Manufacturing

32.1 Introduction

32.2 Theory of Resistance Welding

Basic Resistive Welding

FIGURE 32-1 The basic resistance welding circuit.

Resistive Welding Temperature

Distribution

FIGURE 32-2 The desired

temperature distribution across

the electrodes and workpieces

during resistance welding.

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.

Schematic of Resistive Welding

FIGURE 32-4 The

arrangement of the electrodes

and workpieces in resistance

spot welding.

32.3 Resistance Welding Processes

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.)

Tear Test

FIGURE 32-6 Tear test

of a satisfactory spot

weld, showing how

failure occurs outside of

the weld.

Resistive Welder

FIGURE 32-7 Single-phase,

air-operated, press-type

resistance welder with

microprocessor control.

(Courtesy Sciaky Inc., Chicago, IL.)

Spot Welding Application

Spot Welding Seams

FIGURE 32-8 Seam welds

made with overlapping spots

of varied spacing. (Courtesy

Taylor-Winfield Corporation,

Brookfield, OH.)

Schematic of Seam Welding

FIGURE 32-9 Schematic

representation of the

seam-welding process.

those

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

Projection Welding

FIGURE 32-11 Principle of

projection welding (a) prior to

application of current and

pressure and (b) after formation

of the welds.

32.4 Advantages and Limitations of

Resistance Welding

32.5 Solid-State Welding Processes

Process Summary for RW

Cold Welding

FIGURE 32-12 Small

parts joined by cold

welding. (Courtesy of

Koldweld Corporation,

Willoughby, OH.)

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.)

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.

Schematic for Friction Welding

FIGURE 32-15 Schematic diagram of the equipment

used for friction welding. (Courtesy of Materials

Engineering.)

Inertia Welding

FIGURE 32-16 Schematic

representation of the various

steps in inertia welding. The

rotating part is now attached

to a large flywheel.

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.)

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.)

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.

Features of Stir Welding

Schematic of Ultrasonic Welding

FIGURE 32-20 Diagram of the

equipment used in ultrasonic

welding

Application of Ultrasonic Welding

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.