GTBL042-14 GTBL042-Callister-v2 August 29, 2007 8:59
Learning Objectives
After careful study of this chapter you should be able to do the following:
1.Name and describe four forming operations that
are used to shape metal alloys.
2.Name and describe five casting techniques.
3.State the purposes of and describe procedures
for the following heat treatments: process
annealing, stress relief annealing, normalizing,
full annealing, and spheroidizing.
4.Definehardenability.
5.Generate a hardness profile for a cylindrical
steel specimen that has been austenitized and
then quenched, given the hardenability curve
for the specific alloy, as well as quenching
rate-versus-bar diameter information.
6.Name and briefly describe five forming methods
that are used to fabricate glass pieces.- Briefly describe and explain the procedure by
which glass pieces are thermally tempered.
8.Briefly describe processes that occur during the
drying and firing of clay-based ceramic ware.
9.Briefly describe/diagram the sintering process of
powder particle aggregates.
10.Briefly describe addition and condensation
polymerization mechanisms.
11.Name the five types of polymer additives and,
for each, indicate how it modifies the
properties.
12.Name and briefly describe five fabrication
techniques used for plastic polymers.
14.1 INTRODUCTION
Fabrication techniques are those methods by which materials are formed or manu-
factured into components that may be incorporated in useful products. Sometimes
it also may be necessary to subject the component to some type of processing treat-
ment in order to achieve the required properties. And, on occasion, the suitability of
a material for an application is dictated by economic considerations with respect to
fabrication and processing operations. In this chapter we discuss various techniques
that are used to fabricate and process metals, ceramics, and polymers (and also, for
polymers, how they are synthesized).Fabrication of Metals
Metal fabrication techniques are normally preceded by refining, alloying, and often
heat-treating processes that produce alloys with the desired characteristics. The clas-
sifications of fabrication techniques include various metal-forming methods, casting,
powder metallurgy, welding, and machining; often two or more of them must be
used before a piece is finished. The methods chosen depend on several factors; the
most important are the properties of the metal, the size and shape of the finished
piece, and, of course, cost. The metal fabrication techniques we discuss are classified
according to the scheme illustrated in Figure 14.1.14.2 FORMING OPERATIONS
Forming operations are those in which the shape of a metal piece is changed by
plastic deformation: for example, forging, rolling, extrusion, and drawing are common
forming techniques. Of course, the deformation must be induced by an external force
or stress, the magnitude of which must exceed the yield strength of the material.
Most metallic materials are especially amenable to these procedures, being at least
moderately ductile and capable of some permanent deformation without cracking
or fracturing.