Fundamentals of Materials Science and Engineering: An Integrated Approach, 3e

GTBL042-14 GTBL042-Callister-v2 August 29, 2007 8:59

616 • Chapter 14 / Synthesis, Fabrication, and Processing of Materials

Polymerization

14.19Cite the primary differences between addi-

tion and condensation polymerization tech-

niques.

14.20Nylon 6,6 may be formed by means of a con-

densation polymerization reaction in which

hexamethylene diamine [NH 2 —(CH 2 ) 6 —

NH 2 ] and adipic acid react with one another

with the formation of water as a byproduct.

What masses of hexamethylene diamine and

adipic acid are necessary to yield 20 kg of

completely linear nylon 6,6? (Note:the chem-

ical equation for this reaction is the answer

to Concept Check 14.8.)

Forming Techniques for Plastics

14.21Cite four factors that determine what fabri-

cation technique is used to form polymeric

materials.

Fabrication of Fibers and Films

14.22Why must fiber materials that are melt spun

and then drawn be thermoplastic? Cite two

reasons.

DESIGN PROBLEMS

Heat Treatment of Steels

14.D1A cylindrical piece of steel 38 mm (1^12 in.)

in diameter is to be quenched in moderately

agitated oil. Surface and center hardnesses

must be at least 50 and 40 HRC, respectively.

Which of the following alloys will satisfy

these requirements: 1040, 5140, 4340, 4140,

and 8640? Justify your choice(s).

14.D2A cylindrical piece of steel 44 mm (1^34 in.) in

diameter is to be austenitized and quenched

so that a microstructure consisting of at least

50% martensite will be produced through-

out the entire piece. Of the alloys 4340, 4140,

8640, 5140, and 1040, which will qualify if

the quenching medium is(a)moderately ag-

itated oil and(b)moderately agitated water?

Justify your choice(s).

14.D3A cylindrical piece of 4140 steel is to be

austenitized and quenched in moderately

agitated oil. If the microstructure is to con-

sist of at least 80% martensite throughout

the entire piece, what is the maximum al-

lowable diameter? Justify your answer.

14.D4Is it possible to temper an oil-quenched 4140

steel cylindrical shaft 25 mm (1 in.) in diam-

eter so as to give a minimum yield strength

of 950 MPa (140,000 psi) and a minimum

ductility of 17%EL? If so, specify a temper-

ing temperature. If this is not possible, then

explain why.