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MET > MODULE 6 > Flashcards

MODULE 6 Flashcards

1
Q

material that is typically hard, opaque, shiny, and has
good electrical and thermal conductivity.

A

metal

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2
Q

they can be
hammered or pressed permanently out of shape without breaking or cracking

A

malleable

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3
Q

able to be fused or melted

A

fusible

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4
Q

able to be drawn out into a thin wire

A

ductile

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5
Q

Metal alloys, by virtue of composition, are often grouped into two classes:

A

ferrous and
nonferrous.

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6
Q

iron is the principal constituent

A

Ferrous alloys

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7
Q

not iron based

A

nonferrous are alloys

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8
Q

They are especially important as engineering construction
materials.

A

FERROUS ALLOYS

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9
Q

Their widespread use is accounted for by three factors:

A

(1) iron-containing compounds exist in abundant quantities within the earth’s crust;
(2) metallic iron and steel alloys may be produced using relatively economical extraction,
refining, alloying, and fabrication techniques; and
(3) ferrous alloys are extremely versatile; in that they may be tailored to have a wide range
of mechanical and physical properties.

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10
Q

The principal disadvantage of many ferrous alloys is

A

susceptibility to corrosion.

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11
Q

iron–carbon alloys that may contain appreciable concentrations of other
alloying elements;

A

Steels

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12
Q

Some of the more common steels are classified according to carbon concentration namely:

A

low, medium, and high-carbon types.

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13
Q

contain less than 0.25%C.

A

Low-carbon steels

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14
Q

it is not very responsive to heat treatments
and strengthening is accomplished by cold work.

A

Low-carbon steels

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15
Q

It is soft, weak, tough, ductile, machinable,
weldable and not expensive.

A

Low-carbon steels

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16
Q

They typically have a yield strength of 275 MPa (40,000 psi),

A

Low-carbon steels

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17
Q

tensile
strengths between 415 and 550 MPa (60,000 and 80,000 psi),

A

Low-carbon steels

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18
Q

ductility of 25%EL

A

Low-carbon steels

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19
Q

25%EL.Typical
applications include automobile body components, structural shapes (I-beams, channel and angle
iron), and sheets that are used in pipelines, buildings, bridges, and tin cans.

A

Low-carbon steels

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20
Q

It can also be seen that the
composition of steel is mainly

A

carbon ang manganese

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21
Q

It contains alloying elements such as copper, vanadium, nickel, and molybdenum in
combined concentrations of >10 wt%.

A

High-strength, Low-alloy (HSLA) steels

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22
Q

It is stronger than plain low-C steels. Most

A

High-strength, Low-alloy (HSLA) steels

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23
Q

Most may be
strengthened by heat treatment, giving tensile strengths in excess of 480 MPa (70,000 psi).

A

High-strength, Low-alloy (HSLA) steels

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24
Q

They
are ductile, formable and machinable.

A

High-strength, Low-alloy (HSLA) steels

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25
Q

are more resistant
to corrosion than the plain carbon steels

A

the HSLA steels

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26
Q

contain 0.25-0.60 wt.% of carbon.

A

Medium-Carbon Steels

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27
Q

It is
the hardest, strongest, and yet least ductile of the carbon steels. They

A

High-Carbon Steels

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28
Q

They are almost always used in
a hardened and tempered condition, wear resistant and capable of holding a sharp cutting edge.

A

High-Carbon Steels

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29
Q

The tool and die steels are high-carbon alloys, usually

A

containing chromium, vanadium,
tungsten, and molybdenum.

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30
Q

These steels are used as cutting tools and dies for forming and shaping materials, as well as in knives, razors, hacksaw
blades, springs, and high-strength wire.

A

High-Carbon Steels

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31
Q

The stainless steels are highly resistant to corrosion (rusting) in a variety of environments,
especially the ambient atmosphere.

A

Stainless steels

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32
Q

Their predominant alloying element is chromium;

A

Stainless steels

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33
Q

Corrosion resistance may also be enhanced by

A

nickel and molybdenum additions.

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34
Q

Stainless steels are divided into three classes on the basis of the predominant phase
constituent of the microstructure—

A

martensitic, ferritic, or austenitic.

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35
Q

are capable of being heat treated in such a way that martensite
is the prime microconstituent.

A

Martensitic stainless steels

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36
Q

the austenite (or ɣ) phase field is extended to room
temperature.

A

austenitic stainless steels

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37
Q

composed of the α-ferrite (BCC) phase. Austenitic

A

Ferritic stainless steels

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38
Q

are hardened and strengthened by cold work because they are not heat treatable.

A

Austenitic and ferritic stainless steels

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39
Q

Theoretically, it contains > 2.14 wt.% of carbon.

A

Cast Irons

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40
Q

Usually contains between 3.0-4.5 wt.% C, hence it is very brittle.

A

Cast Irons

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41
Q

They become liquid easily between 1150 0C and 1300 0C.

A

Cast Irons

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42
Q

They are easily
melted and amenable to casting.

A

Cast Irons

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43
Q

It is Inexpensive, machinable and wear resistant.

A

Cast Irons

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44
Q

The most
common cast iron types are

A

gray, nodular, white, malleable, and compacted graphite

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45
Q

The carbon and silicon contents of gray cast irons vary between 2.5 and 4.0 wt% and 1.0 and 3.0 wt%,

A

Gray Iron

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46
Q

is comparatively weak and brittle in tension.

A

gray iron

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47
Q

Strength and ductility are much higher under compressive loads.

A

Gray Iron

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48
Q

They are very effective in
damping vibrational energy.

A

Gray Iron

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49
Q

gray irons exhibit a high resistance to wear and the
least expensive of all metallic materials

A

Gray Iron

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50
Q

Adding a small amount of magnesium and/or cerium to the gray iron before casting
produces a distinctly different microstructure and set of mechanical properties.

A

Ductile (or Nodular) Iron

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51
Q

It has mechanical characteristics approaching those of steel.

A

Ductile (or Nodular) Iron

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52
Q

For low-silicon cast irons (containing less than 1.0 wt% Si) and rapid cooling rates, most
of the carbon exists as cementite instead of graphite.

A

White Iron

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53
Q

A fracture surface of this alloy has a white
appearance, and thus it is termed

A

white cast iron

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54
Q

As a consequence of large amounts of the cementite phase, _________
is extremely hard but also very brittle, to the point of being virtually unmachinable.

A

White Iron

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55
Q

Its use is
limited to applications that necessitate a very hard and wear-resistant surface, without a high
degree of ductility—for example, as rollers in rolling mills

A

White Iron

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56
Q

Heating white iron at temperatures between 800 and 900 oC for a prolonged time period
and in a neutral atmosphere (to prevent oxidation) causes a decomposition of the cementite,
forming graphite, which exists in the form of clusters or rosettes surrounded by a ferrite or
pearlite matrix, depending on cooling rate. The

A

Malleable Iron

57
Q

Silicon
content ranges between 1.7 and 3.0 wt%,

A

Compacted Graphite Iron

58
Q

carbon concentration is normally between
3.1 and 4.0 wt%

A

Compacted Graphite Iron

59
Q

Tensile and yield strengths for _______ are comparable
to values for ductile and malleable irons, yet are greater than those observed for the higher
strength gray irons.

A

Compacted Graphite Iron

60
Q

are intermediate between values for gray
and ductile irons; also, moduli of elasticity range between 140 and 165 GPa ( and psi).

A

Compacted Graphite Iron

61
Q

desirable characteristics of ______ include the
following: higher thermal conductivity, better resistance to thermal shock (i.e., fracture resulting
from rapid temperature changes) and lower oxidation at elevated temperatures.

A

Compacted Graphite Iron

62
Q

are now being used in a number of important applications—these include: diesel
engine blocks, exhaust manifolds, gearbox housings, brake discs for high-speed trains, and
flywheels.

A

Compacted Graphite Iron

63
Q

are metals that do not have any iron in them at all.

A

NONFERROUS ALLOYS

64
Q

It is not attracted to
the magnet and do not rust easily when exposed to moisture.

A

NONFERROUS ALLOYS

65
Q

It is highly resistant to corrosion in diverse environments including the ambient
atmosphere, seawater, and some industrial chemicals.

A

Copper and Its Alloys

66
Q

most common copper alloys

A

brasses

67
Q

are alloys of copper and several other elements, including tin, aluminum, silicon,
and nickel.

A

bronzes

68
Q

most common heat-treatable copper alloys

A

beryllium coppers.

69
Q

tensile strengths as high as 1400 MPa (200,000
psi),

A

Copper and Its Alloys

70
Q

Applications include jet aircraft landing gear
bearings and bushings, springs, and surgical and dental instruments.

A

Copper and Its Alloys

71
Q

are characterized by a relatively low density (2.7 g/cm3 as compared to 7.9 g/cm3 for steel), high electrical and thermal conductivities, and a resistance to
corrosion in some common environments,

A

Aluminum and its alloys

72
Q

The chief limitation of _________ is its low
melting temperature 660 oC.

A

aluminum

73
Q

aluminum alloys are classified as either

A

cast or wrought.

74
Q

more common applications of aluminum alloys include aircraft structural parts, beverage
cans, bus bodies, and automotive parts (engine blocks, pistons, and manifolds).

A

Aluminum and Its Alloys

75
Q

most outstanding characteristic of _____ is its density, 1.7 g/cm3, which is the
lowest of all the structural metals.

A

magnesium

76
Q

are relatively unstable and especially susceptible to corrosion in
marine environments.

A

magnesium alloys

77
Q

have
replaced engineering plastics that have comparable densities in as much as the magnesium
materials are stiffer, more recyclable, and less costly to produce.

A

magnesium alloys

78
Q

The pure metal has a relatively low density (4.5 g/cm3),
a high melting point [1668 oC ], and an elastic modulus of 107 GPa ( psi).

A

Titanium and Its Alloys

79
Q

are
extremely strong; room temperature tensile strengths as high as 1400 MPa (200,000 psi) are
attainable, yielding remarkable specific strengths.

A

Titanium alloys

80
Q

major limitation of _______ is its chemical
reactivity with other materials at elevated temperatures and quite expensive.

A

titanium

81
Q

the corrosion resistance of _____ at normal temperatures is
unusually high; they are virtually immune to air, marine, and a variety of industrial environments.

A

titanium alloys

82
Q

They are commonly utilized in airplane structures, space vehicles, surgical implants, and in the
petroleum and chemical industries.

A

Titanium and Its Alloys

83
Q

Metals that have extremely high melting temperatures are classified as

A

refractory
metals.

84
Q

Included in this group are niobium (Nb), molybdenum (Mo), tungsten (W), and tantalum
(Ta).

A

The Refractory Metals

85
Q

are utilized for extrusion dies and structural parts in space vehicles;
incandescent light filaments, x-ray tubes,

A

Molybdenum alloys

86
Q

welding electrodes

A

tungsten
alloys

87
Q

is immune to chemical attack by virtually all environments at temperatures below
150 oC and is frequently used in applications requiring such a corrosion-resistant material.

A

Tantalum

88
Q

have superlative combinations of properties.

A

superalloys

89
Q

Most are used in aircraft
turbine components, which must withstand exposure to severely oxidizing environments and high
temperatures for reasonable time periods.

A

superalloys

90
Q

These materials are classified according to the
predominant metal(s) in the alloy, of which there are three groups—

A

iron–nickel, nickel, and cobalt.

91
Q

are a group of eight elements that have some physical
characteristics in common.

A

The Noble Metals

92
Q

They are expensive (precious) and are superior or notable (noble) in
properties, that is, characteristically soft, ductile, and oxidation resistant.

A

The Noble Metals

93
Q

are most
common and are used extensively in jewelry.

A

silver, gold, platinum,

94
Q

are highly resistant to corrosion in many environments, especially
those that are basic (alkaline).

A

Nickel and its alloys

95
Q

are
mechanically soft and weak, have low melting temperatures, are quite resistant to many corrosion
environments, and have recrystallization temperatures below room temperature.

A

Lead, tin, and their alloys

96
Q

also is a relatively soft metal having a low melting temperature and a
subambient recrystallization temperature.

A

Unalloyed zinc

97
Q

are ductile and have other mechanical characteristics that are
comparable to those of titanium alloys and the austenitic stainless steels.

A

Zirconium and its alloys

98
Q

the primary
asset of these alloys is their resistance to corrosion in a host of corrosive media, including
superheated water.

A

Zirconium and its alloys

99
Q

are those in which the shape of a metal piece is changed by plastic
deformation;

A

FORMING OPERATIONS

100
Q

is mechanically working or deforming a single piece of a normally hot metal; this
may be accomplished by the application of successive blows or by continuous squeezing.

A

Forging

101
Q

Forgings are classified as:

A

closed die
open die

102
Q

a force is brought to bear on two or more die halves having the finished shape
such that the metal is deformed in the cavity between them

A

closed die

103
Q

-two dies having simple geometric shapes (e.g., parallel flat, semicircular) are
employed, normally on large workpieces.

A

open die

104
Q

is the most widely used deformation process, consists of passing a piece of metal
between two rolls; a reduction in thickness results from compressive stresses exerted by the rolls.

A

Rolling

105
Q

may be used in the production of sheet, strip, and foil with high quality surface finish.

A

Cold rolling

106
Q

Circular shapes as well as I-beams and railroad rails are fabricated

A

grooved rolls.

107
Q

a bar of metal is forced through a die orifice by a compressive force that is

applied to a ram; the extruded piece that emerges has the desired shape and a reduced cross-
sectional area.

A

Extrusion

108
Q

is the pulling of a metal piece through a die having a tapered bore by means of a
tensile force that is applied on the exit side.

A

Drawing

109
Q

is a fabrication process whereby a totally molten metal is poured into a mold cavity
having the desired shape; upon solidification, the metal assumes the shape of the mold but
experiences some shrinkage.

A

Casting

110
Q

ordinary sand is used as the mold
material.

A

Sand Casting

111
Q

A two-piece mold is formed by packing sand around a pattern that has the shape of the
intended casting.

A

Sand Casting

112
Q

the liquid metal is forced into a mold under pressure and at a relatively high
velocity, and allowed to solidify with the pressure maintained.

A

Die Casting

113
Q

However, this technique lends itself only to relatively small pieces and to alloys of zinc,
aluminum, and magnesium, which have low melting temperatures.

A

Die Casting

114
Q

(sometimes called lost-wax) casting,

A

Investment Casting

115
Q

This technique is employed when high dimensional accuracy, reproduction of fine detail,
and an excellent finish are require,

A

Investment Casting

116
Q

expendable pattern is a foam that can be formed by compressing polystyrene beads into the
desired shape and then bonding them together by heating.

A

Lost Foam Casting

117
Q

Metal alloys that most commonly use this technique are cast irons and aluminum alloys;
furthermore, applications include automobile engine blocks, cylinder heads, crankshafts, marine
engine blocks, and electric motor frames.

A

Lost Foam Casting

118
Q

At the conclusion of extraction processes, many molten metals are solidified by casting
into large ingot molds.

A

Continuous Casting

119
Q

compaction of powdered metal, followed by a
heat treatment to produce a denser piece.

A

Powder Metallurgy

120
Q

This method is especially suitable for metals having
low ductilities, since only small plastic deformation of the powder particles need occur.

A

Powder Metallurgy

121
Q

Furthermore, parts that require very close dimensional tolerances (e.g., bushings and gears)
may be economically produced using this technique.

A

Powder Metallurgy

122
Q

two or
more metal parts are joined to form a single piece when one-part fabrication is expensive or
inconvenient.

A

Welding

123
Q

variety of
welding methods exist,

A

including arc and gas welding, as well as brazing and soldering.

124
Q

is a heat treatment process in which a material is exposed to an elevated
temperature for an extended time period and then slowly cooled.

A

Annealing

125
Q

is carried
out to relieve stresses; to increase softness, ductility, and toughness; and/or to produce a specific
microstructure. Annealing

A

Annealing

126
Q

Annealing process consists of three stages:

A

(1) heating to the desired temperature,
(2) holding or “soaking” at that temperature, and
(3) cooling, usually to room temperature.

127
Q

a heat treatment process used to refine the grains and produce a more uniform
and desirable size distribution.

A

Normalizing

128
Q

is the process for making material harder.

A

Hardening

129
Q

is a heat treatment method mostly used to increase the yield
strength of malleable metals.

A

Ageing or Precipitation Hardening

130
Q

produces uniformly dispersed particles within a metal’s grain
structure which bring about changes in properties.

A

Ageing or Precipitation Hardening

131
Q

is especially common for boiler parts, air bottles, accumulators, etc. This
method takes the metal to a temperature just below its lower critical border.

A

Stress relieving

132
Q

Tempering carried out by preheating previously quenched or normalized steel to a
temperature below the lower critical temperature (often from 205 to 595 ̊C), holding, and then
cooling to obtain the desired mechanical properties.

A

Tempering

133
Q

The higher the temperature in the tempering process,

A

the lower the hardness.

134
Q

is the process of hardening the surface of steel while
leaving the interior unchanged.

A

Case hardening or Surface hardening

135
Q

The principal forms of casehardening are :

A

Carburizing
Cyaniding
Nitriding

136
Q

It is process of increasing the carbon content on the surface of steel. It is a heat
treatment process in which iron or steel is heated in the presence of another material (in the
range of 900 to 950 °C ) which liberates carbon as it decomposes

A

Carburizing

137
Q

It is a process of producing hard surfaces by immersing low carbon steel in cyanide
bath maintained at 800°C – 850°C. The parts are then quenched in water or oil. This
process helps to maintain bright finish of the parts.

A

Cyaniding

138
Q
A

MET (11 decks)

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