Properties of Materials


"those characteristics that help identify
and distinguish one material from
another” (p. 140)
Page numbers are in reference to: Jacobs, James A. and Thomas F. Kilduff. (2005). Engineering materials
technology, 5th Edition. Englewood Cliffs, NJ: Prentice-Hall, Inc.
Physical Properties

properties that "result from the
response of the material to some
environmental variable." (p.140)
Physical properties




Density & Specific Gravity
Porosity
Color
Other
Mechanical Properties

"a measure of a material's ability to
carry or resist mechanical forces or
stresses.” (p. 140)
Stress


"the resistance offered by a material to
external forces or loads.” (p.141)
sigma = F / A
Strain


"change in a physical dimension . . .
Deformation.” (p.142)
unit deformation. (p.142)
Stress-Strain Diagrams (p.144)





Elastic Region
Plastic Region
Yield Point
Ultimate Strength
Fracture
FIGURE 4-4 Engineering symbols for the sides of the triangle shown in the elastic region of the curve, 2 (theta) is the slope
angle, E is the Modulus of elasticity or Young’s Modulus and is computed:
E=
= tan
and
is the symbol that means “a measurable change in.” Stress–strain diagram.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Modulus of Elasticity


"the ratio of the stress to the strain in
the elastic region of the stress-strain
diagram." (p.145)
AKA: Young’s Modulus, MOE, E
FIGURE 4-4 Engineering symbols for the sides of the triangle shown in the elastic region of the curve, 2 (theta) is the slope
angle, E is the Modulus of elasticity or Young’s Modulus and is computed:
E=
= tan
and
is the symbol that means “a measurable change in.” Stress–strain diagram.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 4-6
Typical stress-strain diagrams.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Strength





tensile
compressive
shear
torsion
other
Calculating Strength



Strength = max. load / cross-sectional area
(psi)
(pascals)
pounds
square inches
newtons
square meters
Tensile Strength


or ultimate strength
p. 146
FIGURE 4-4 Engineering symbols for the sides of the triangle shown in the elastic region of the curve, 2 (theta) is the slope
angle, E is the Modulus of elasticity or Young’s Modulus and is computed:
E=
= tan
and
is the symbol that means “a measurable change in.” Stress–strain diagram.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 4-3
(a) Rod under a tensile load. (b) Standard tensile test specimen or gage.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Yield Strength


stress that produces 0.002 in/in strain
p.146
FIGURE 4-4 Engineering symbols for the sides of the triangle shown in the elastic region of the curve, 2 (theta) is the slope
angle, E is the Modulus of elasticity or Young’s Modulus and is computed:
E=
= tan
and
is the symbol that means “a measurable change in.” Stress–strain diagram.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Resilience


the amount of energy that a material
can absorb without plastic deformation.
p.147
Ductility



the ability to "undergo large plastic
deformation without fracture.”
(also, the ability to be drawn into a
wire.)
(p.149)
FIGURE 4-10
Stress-strain curves for (a) ductile material.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 4-10
Stress-strain curves for (b) brittle material.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Toughness


"the ability or capacity of a material to
absorb energy during plastic
deformation.” (p.152)
Influenced by temperature
Malleability, workability

(p.156)
Flexural or Bending Strength

(p.157)
Beam bending

Compression, Tension, & Neutral axis
FIGURE 4-18
A simple beam deflected by a cyclic, transverse load.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Fatigue Strength


(p.158)
Endurance
FIGURE 4-21
s-N diagram for a typical fiberglass composite material.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 4-22
s-N diagram for a typical low-carbon steel.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Shear Strength

Single or Double
FIGURE 4-9
load.
Shearing stress and strain. See Figure 4-10 for sheet metal shearing. (a) Before shear load. (b) After shear
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Creep


"a slow process of plastic deformation
that takes place when a material is
subjected to a constant condition of
loading (stress) below its normal yield
strength." (p.163)
(cf. bookshelves)
Torsion

"the process of twisting." (p.164)
FIGURE 4-27 (b) Torsional fracture. Torsional (twisting) loads produce spiral types of failure. Note the curved line from (A)
to (C) is part of a helix.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Hardness



"a measure of a material's resistance to
penetration (local plastic deformation)
or scratching." (p.167)
Hardness testing instrumentation
Hardness scales
FIGURE 4-30
(a) Photograph of Tukon microhardness tester (Measurement Systems Div., Page Wilson Corp.)
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 4-30
(b) Photograph of Rockwell hardness tester. (Measurement Systems Div., Page Wilson Corp.)
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 4-30 (c) Photograph of Air-O-Brinell metal hardness tester with digital readout of Brinell values. (Tinius Olsen
Testing Machine Co.)
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 4-30
(d) Microhardness penetrator (Knoop and Vickers) indentations. (Wilson Instrument Division of ACCO)
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 4-30
(e) Various standard loads for the Rockwell harness tester. (Wilson Instrument Division of ACCO)
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 4-30
(f) Brale sphero-conical diamond penatrator. (Wilson Instrument Division of ACCO)
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Hardness Scales (p. 168)
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Chemical Properties (p.176)





oxidation
corrosion resistance
acid/alkali resistance
behavior in chemical reactions
other
Oxidation


"the interaction of oxygen with
elements in a material to cause
structural changed due to the
movement of valence electrons in the
atoms of the material. An oxidized
material loses electrons from atoms or
ions." (p.183)
(The opposite of oxidation is reduction.)
Corrosion Resistance

"the ability to resist oxidation." (p.185)
pH






acid --> alkali
0 to 14
7 is neutral (pure water)
H+ or OH- ions
H2SO4, HCl, HNO3
NaOH, Ca(OH)2
Other Properties


Other Chemical Properties
Thermal Properties (p.194)






Specific heat
Coefficient of linear thermal expansion
Electrical Properties
Magnetic Properties
Optical Properties
Other Properties
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Materials Testing


Purpose
Type



Destructive
Non-destructive
Standards

ANSI and ASTM
FIGURE 4-51
Potential weight savings trend for future structural materials. (NASA)
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 4-1 (a) Cryogenic processing coupled with coatings of engine parts in race cars has increased the life of high
performance race cars three to five times.
James A. Jacobs & Thomas F. Kilduff
Engineering Materials Technology, Fourth
Edition
Copyright ©2001 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.