Chapter 5: Mechanical Properties of Metals

Question 1

Metals are known to be:

Answer 1

Malleable & Ductile
High density
High Melting Point
High Thermal Conductivity
High Electric Conductivity

Question 2

how much force an
object can withstand without bending
or breaking (compression, tension, &
shear)

Answer 2

strength

Question 3

refers to a material’s
response to tensile stress, or its
ability to be stretched, rolled or
extruded without breaking.

Answer 3

ductility

Question 4

refers to a material’s
response to tensile stress, or its
ability to be stretched, rolled or
extruded without breaking.

Answer 4

ductility

Question 5

refers to compressive stress, as in
flattening.

Answer 5

malleability

Question 6

important properties of metals

Answer 6

ductility
malleability
toughness
fatigue resistance
hardness

Question 7

represents an ideal
balance between strength and ductility.
The toughest metals are those that can
absorb the highest amounts of energy
before fracturing. In simple terms, the
toughest parts are the most difficult to
break

Answer 7

toughness

Question 8

is a measure of a
part’s ability to undergo repeated,
cyclical stress without fracturing or
permanently deforming.

Answer 8

Fatigue resistance

Question 9

A material’s power to
resist a permanent change in shape
when acted upon by an external force

Answer 9

hardness

Question 10

Crystalline Structure of Metals

Answer 10

FCC (Face-centered cubic)
BCC (Body-centered cubic)
HCP (Hexagonal close packed)

Question 11

mechanical properties of FCC

Answer 11

Low young modulus
Low yield strength
Low hardness
Good ductility and high ability for
forming.

Question 12

mechanical properties of BCC

Answer 12

High yield strength
High young modulus
High hardness
High tensile strength
Limited ability to forming

Question 13

mechanical properties of HCP

Answer 13

Brittle
Low yield strength
Inability to forming

Question 14

The ___ of a material
reflects its response or deformation in
relation to an applied load or force.

Answer 14

mechanical behavior

Question 15

Key mechanical design properties are

Answer 15

stiffness, strength, hardness, ductility,
and toughness

Question 16

One of the most common mechanical
stress–strain tests is performed in

Answer 16

tension

Question 17

It is conducted in a manner similar to the tensile
test, except that the force is compressive and the specimen contracts along
the direction of the stress. Same equation use in strain and stress as in
tension. Used when a material’s behavior under large and
permanent (i.e., plastic) strains is desired, as in manufacturing applications,
or when the material is brittle in tension.

Question 18

is a variation of pure shear in which a
structural member is twisted in the manner of
torsional forces produce a rotational motion about
the longitudinal axis of one end of the member
relative to the other end.

Answer 18

torsion

Question 19

is a function of the orientations of the
planes upon which the stresses are taken to act.

Answer 19

stress state

Question 20

a more complex stress state is present that
consists of a tensile (or normal) stress 𝜎
′
that acts normal to
the p-p’ plane and, in addition, a ___ that acts
parallel to this plane; both of these stresses are represented
in the figure.

Answer 20

shear stress 𝝉’

Question 21

is non-permanent,
which means that when the applied load is
released, the piece returns to its original
shape. As shown in the stress–strain plot
Upon release of the load, the line is
traversed in the opposite direction, back to
the origin.

Answer 21

elastic deformation

Question 22

With increasing temperature,
the modulus of elasticity
___

Answer 22

decreases

Question 23

defined as the
ratio of the lateral and
axial strains

Answer 23

Poisson’s ratio 𝝂

Question 24

In most metals, G is about ___

Answer 24

0.4E

Question 25

The stress necessary to continue plastic deformation in metals increases to a maximum, point M and then decreases to the eventual fracture, point F. Unit Mpa or psi

Answer 25

Tensile Strength (TS)

Question 26

It is a measure of the degree of plastic deformation that has been sustained at fracture. Ability of metal to drawn out into wire. Performance under tensile stresses

Answer 26

ductility

Question 27

Knowledge of the ductility of materials is important for at least two reasons.

Answer 27

1.) It indicates to a designer the degree to which a structure will deform plastically before before fracture 2.) It specifies the degree of allowable deformation during fabrication operations.

Question 28

Metal that experiences very little or no plastic deformation upon fracture

Answer 28

brittle

Question 29

Is the capacity of a material to absorb energy when it is deformed elastically and then, upon unloading, to have this energy recovered.

Answer 29

resilience

Question 30

is the ability of a material to absorb energy and plastically deform before fracturing

Answer 30

toughness

Question 31

which is a measure of a material’s resistance to localized plasti

Answer 31

hardness

Question 32

Values normally range between

Answer 32

1.2 and 4.0

Question 33

Selection of ___ will depend on a number of factors, including economics, previous experience, the accuracy with which mechanical forces and material properties may be determined, and, most important, the consequences of failure in terms of loss of life and/or property damage.

Answer 33

N

Question 34

showing linear elastic deformation for loading and unloading cycles.

Answer 34

Schematic stress–strain diagram