Page 274 - Materials Science and Engineering An Introduction

246 • Chapter 7 / Dislocations and Strengthening Mechanisms

Iron–Carbon Alloys Recrystallization Normalizing
(Steels) (Processing) (Chapter 7) (Chapter 11)
Annealing temperature (°F) 1000
600 800
600 60
900 A cm
Tensile strength Normalizing
50 Full annealing
Tensile strength (MPa) 40 Ductility (%EL) Temperature (°C) 800 A 1
500
A 3
700
400
Ductility 30
20 600
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
300
Recrystallization Composition (wt% C)

200 300 400 500
Annealing temperature (°C)

Important Terms and Concepts
cold working recovery slip system
critical resolved shear stress recrystallization solid-solution strengthening
dislocation density recrystallization temperature strain hardening
grain growth resolved shear stress
lattice strain slip

REFERENCES

Argon, A. S., Strengthening Mechanisms in Crystal Plasticity, Read, W. T., Jr., Dislocations in Crystals, McGraw-Hill, New
Oxford University Press, New York, 2008. York, 1953.
Hirth, J. P., and J. Lothe, Theory of Dislocations, 2nd edition, Weertman, J., and J. R. Weertman, Elementary Dislocation
Wiley-Interscience, New York, 1982. Reprinted by Theory, Macmillan, New York, 1964. Reprinted by Oxford
Krieger, Malabar, FL, 1992. University Press, New York, 1992.
Hull, D., and D. J. Bacon, Introduction to Dislocations, 5th
edition, Butterworth-Heinemann, Oxford, 2011.

QUESTIONS AND PROBLEMS
Problem available (at instructor’s discretion) in WileyPLUS
Basic Concepts far (in miles) would this chain extend? Now sup-
9
2
Characteristics of Dislocations pose that the density is increased to 10 mm by
7.1 To provide some perspective on the dimensions cold working. What would be the chain length of
3
of atomic defects, consider a metal specimen dislocations in 1000 mm of material?
2
5
with a dislocation density of 10 mm . Suppose 7.2 Consider two edge dislocations of opposite sign
3
3
that all the dislocations in 1000 mm (1 cm ) were and having slip planes separated by several atomic
somehow removed and linked end to end. How distances, as indicated in the following diagram.