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IE 301 > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

Alloys containing more than 50wt.% Fe

A

Ferrous Alloys

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2
Q

Alloys containing less than 50wt.% Fe

A

Nonferrous Alloys

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3
Q

Based on carbon content:

(< 0.008wt% C)

A

Pure iron

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4
Q

Based on carbon content:

0.008 ~ 2.14wt% C

A

Steels

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5
Q

In most steels the microstructure consists of both

A

a and Fe3C phases

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6
Q

Carbon concentrations in commercial steels rarely exceed

A

1.0 wt%

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7
Q

Based on carbon content:

2.14 ~ 6.70wt% C

A

Cast irons

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8
Q

Commercial cast irons normally contain less than

A

4.5wt% C

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9
Q

Less than 0.25 wt%C, containing only residual concentrations of impurities and a little manganese.

A

Plain carbon steels

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10
Q

About 90% of all steel made is

A

carbon steel

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11
Q

more alloying elements are intentionally added in specific concentrations

A

Alloy steels

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12
Q

What are the 3 Ferrous Alloys — Steels?

A

Plain carbon steels
Alloy steels
Stainless steels

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13
Q

The first two digits indicate the

A

alloy content

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14
Q

The last two digits indicate the

A

the carbon concentration

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15
Q

For plain carbon steels, the first two digits are

A

1 and 0

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16
Q

alloy steels are designated by

A

other initial two-digit combinations (e.g., 13, 41, 43)

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17
Q

The third and fourth digits represent

A

the weight percent carbon multiplied by 100

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18
Q

For example, a 1040 steel is

A

a plain carbon steel containing 0.40 wt% C

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19
Q

A four-digit number

A

the first two digits indicate the alloy content; the last two, the carbon concentration

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20
Q

AISI

A

American Iron and Steel Institute

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21
Q

SAE

A

Society of Automotive Engineers

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22
Q

UNS

A

Uniform Numbering System

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23
Q

Low-carbon steels

A

Less than 0.25 wt%C

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24
Q

Medium-carbon steels

A

0.25 ~ 0.60 wt%C

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25
Q

High-carbon steels

A

0.60 ~ 1.4 wt%C

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26
Q

Unresponsive to heat treatments intended to form martensite; strengthening is accomplished by cold work

A

Low-Carbon Steels

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27
Q

Microstructures of low-carbon steel

A

ferrite and pearlite

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28
Q

Relatively soft and weak, but having outstanding ductility and toughness

A

Low-Carbon Steels

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29
Q

Typically, sy = 275 MPa, sUT = 415~550 MPa, and ductility = 25%EL

A

Low-Carbon Steels

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30
Q

Machinable, weldable, and, of all steels, are the least expensive to produce

A

Low-Carbon Steels

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31
Q

Applications for low-carbon steels:

A

automobile body components, structural shapes, and sheets used in pipelines, buildings, bridges, etc.

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32
Q

0.25 ~ 0.60 wt% C

A

Medium-Carbon Steels

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33
Q

May be heat treated by austenitizing, quenching, and then tempering to improve their mechanical

A

Medium-Carbon Steels

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34
Q

Often utilized in the tempered condition

A

Medium-Carbon Steels

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35
Q

Microstructures of medium carbon steel:

A

tempered martensite

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36
Q

Stronger than low-carbon steels and weaker than high-carbon steels

A

Medium-Carbon Steels

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37
Q

Applications for medium-carbon steels:

A

railway wheels and tracks, gears, crankshafts, and other machine parts and high-strength structural components calling for a combination of high strength, wear resistance, and toughness

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38
Q

0.60 ~ 1.4 wt%C

A

High-Carbon Steels

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39
Q

Used in a hardened and tempered condition

A

High-Carbon Steels

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40
Q

Hardest, strongest, and yet least ductile; especially wear resistant and capable of holding a sharp cutting edge

A

High-Carbon Steels

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41
Q

Containing Cr, V, W, and Mo; these alloying elements form very hard and wear-resistant carbide compounds (e.g., Cr23C6, V4C3, and WC)

A

High-Carbon Steels

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42
Q

Applications for high carbon steel:

A

cutting tools and dies for forming and shaping materials, knives, razors, hacksaw blades, springs, and high-strength wire

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43
Q

Stainless steels are selected for their excellent

A

resistance to corrosion

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44
Q

Stainless steels are divided into three classes:

A

martensitic, ferritic, or austenitic

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45
Q

The predominant alloying element in stainless steel is

A

chromium; a concentration of at least 11 wt% Cr is required

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46
Q

The predominant alloying element __________

A

permits a thin, protective surface layer of chromium oxide to form when the steel is exposed to oxygen

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47
Q

Aluminum and aluminum alloys are the most widely used

A

nonferrous metals

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48
Q

strengthened by cold working and alloying

A

Aluminum alloys

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49
Q

Nonheat-treatable: single phase, solid solution strengthening

A

Aluminum alloys

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50
Q

Low density (2.7 g/cm3), as compared to 7.9 g/cm3 for steel
High electrical and thermal conductivity
Resistant to corrosion in some common environments
Easily formed and thin Al foil sheet may be rolled
Al has an FCC crystal structure; its ductility is retained even at very low temperatures
Limitation: low melting temperature (660°C)

A

Properties of aluminum alloys

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51
Q

Al alloys can provide a weight savings of up to ___ compared to an equivalent steel structure

A

55%

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52
Q

________ is used in the manufacture of aircraft and for fuel tanks in spacecraft

A

Aluminum plate

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53
Q
  • So soft and ductile that it is difficult to machine
  • Unlimited capacity to be cold worked
  • Highly resistant to corrosion in diverse environments
A

Unalloyed copper

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54
Q

strengthened by cold working and/or solid-solution alloying

A

Copper alloys

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55
Q

________ and _______ are two common copper alloys

A

Bronze and brass

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56
Q

Applications for copper alloys:

A

costume jewelry, cartridge casings, automotive radiators, musical instruments, electronic packaging, and coins

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57
Q

Bronze is an alloy of _______ and _____.

A

copper and tin

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58
Q

May contain up to 25% tin

A

Bronze

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59
Q

Brass is an alloy of ______

and ____.

A

copper

zinc

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60
Q

Contain 5-30% zinc

A

Brass

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61
Q

The zinc ________ the strength of the copper

A

increases

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62
Q

_______ and _______ are also increased by the zinc.

A

Ductility

formability

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63
Q

Relatively new engineering material that possess an extraordinary combination of properties

A

Titanium

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64
Q

Low density (4.5 g/cm3)

A

Titanium

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65
Q

High melting temperature (1668°C), high elastic modulus (107 GPa)

A

Titanium

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66
Q

What are the limitations of titanium?

A
  • Chemical reactivity with other materials and oxidation problems at elevated temperatures
  • Cost
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67
Q

What are the applications of titanium?

A

High-strength prosthetic implants, petroleum & chemical-processing equipment, airframe structural components

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68
Q

Most polymers are

A

hydrocarbons

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69
Q

Each carbon singly bonded to four other atoms

A

Saturated hydrocarbons

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70
Q

Example of a Saturated hydrocarbons

A

Ethane, C2H6

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71
Q

Double & triple bonds somewhat unstable – can form new bonds

A

Unsaturated Hydrocarbons

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72
Q

_______ found in ethylene (ethene) - C2H4

A

Double bond

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73
Q

_________ found in acetylene (ethyne) - C2H2

A

Triple bond

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74
Q

two compounds with same chemical formula can have quite different structures

A

Isomerism

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75
Q

Example of Isomerism

A

C8H18:
normal-octane
2,4-dimethylhexane

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76
Q

_______ is a long-chain hydrocarbon

A

polyethylene

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77
Q

Molecular Shape is also known as

A

Conformation

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78
Q

chain bending and twisting are possible by rotation of carbon atoms around their chain bonds

A

Molecular Shape

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79
Q

not necessary to break chain bonds to ________

A

alter molecular shape

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80
Q

two or more monomers polymerized together

A

Copolymers

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81
Q

A and B randomly positioned along chain

A

random

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82
Q

A and B alternate in polymer chain

A

alternating

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83
Q

large blocks of A units alternate with large blocks of B units

A

block

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84
Q

chains of B units grafted onto A backbone

A

graft

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85
Q

Crystallinity in Polymers

A
  • Ordered atomic arrangements involving molecular chains

- Crystal structures in terms of unit cells

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86
Q

Polymer Crystalline regions

A
  • thin platelets with chain folds at faces

- Chain folded structure

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87
Q

Polymers _____ 100% crystalline

A

rarely

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88
Q

in Polymer Crystallinity, it is difficult for all regions of all chains to become ________

A

aligned

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89
Q

Degree of crystallinity is expressed as

A

% crystallinity

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90
Q

Some physical properties depend on

A

% crystallinity

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91
Q

Heat treating causes crystalline regions to _____ and % crystallinity to _______

A

grow

increase

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92
Q

Some semicrystalline polymers form

A

spherulite structures

93
Q

Alternating chain-folded crystallites and amorphous regions

A

Semicrystalline Polymers

94
Q

Spherulite structure for relatively _____ growth rates

A

rapid

95
Q

Mass of a mole of chains

A

Molecular weight

96
Q

Not all chains in a polymer are of the

A

same length

97
Q

there can be a ________ of molecular weights

A

distribution

98
Q

average number of repeat units per chain

A

Degree of Polymerization, DP

99
Q

The fracture strengths of polymers is _____ of those for metals

A

10%

100
Q

Deformation strains for polymers are

A

> 1000%

101
Q

for most metals, deformation strains are

A

< 10%

102
Q

Drawing

A
  • stretches the polymer prior to use

- aligns chains in the stretching direction

103
Q

What are the results of drawing?

A
  • increases the elastic modulus (E) in the stretching direction
  • increases the tensile strength (TS) in the stretching direction
  • decreases ductility (%EL)
104
Q

Annealing after drawing:

A
  • decreases chain alignment

- reverses effects of drawing (reduces E and TS, enhances %EL)

105
Q

Predeformation by Drawing

A

Contrast to effects of cold working in metals

106
Q

Compare elastic behavior of elastomers with the:

A
  • brittle behavior (of aligned, crosslinked & network polymers)
  • plastic behavior (of semicrystalline polymers) (as shown on previous slides)
107
Q

-little crosslinking
- ductile
- soften w/heating
- polyethylene
polypropylene
polycarbonate
polystyrene

A

Thermoplastics

108
Q
  • significant crosslinking (10 to 50% of repeat units)
  • hard and brittle
  • do NOT soften w/heating
  • vulcanized rubber, epoxies, polyester resin, phenolic resin
A

Thermosets

109
Q

Decreasing T

A
  • increases E
  • increases TS
  • decreases %EL
110
Q

Increasing strain rate

A
  • increases E
  • increases TS
  • decreases %EL
111
Q

Both Tm and Tg increase with

A

increasing chain stiffness

112
Q

Chain stiffness increased by presence of

A
  1. Bulky sidegroups
  2. Polar groups or sidegroups
  3. Chain double bonds and aromatic chain groups
113
Q

formation prior to cracking

A

Craze

114
Q

What happens during crazing?

A
  • plastic deformation of spherulites

- formation of microvoids and fibrillar bridges

115
Q

There are two types of polymerization:

A
  • Addition (or chain) polymerization

- Condensation (step) polymerization

116
Q

Polymer Additives can

A

Improve mechanical properties, process-ability, durability, etc.

117
Q

Added to improve tensile strength & abrasion resistance, toughness & decrease cost

A

Fillers

118
Q

What are some examples of Polymer fillers?

A

carbon black, silica gel, wood flour, glass, limestone, talc, etc

119
Q
  • Added to reduce the glass transition temperature Tg below room temperature
  • Presence of plasticizer transforms brittle polymer to a ductile one
  • Commonly added to PVC - otherwise it is brittle
A

Plasticizers

120
Q
  • can be reversibly cooled & reheated

i. e. recycled heat until soft, shape as desired, then cool

A

Thermoplastic

121
Q
  • when heated forms a molecular network (chemical reaction)
  • degrades (doesn’t melt) when heated
  • a prepolymer molded into desired shape, then chemical reaction occurs
A

Thermoset

122
Q

Polymer Fibers - length/diameter

A

> 100

123
Q

Primary use is in textiles

A

Polymer Fibers

124
Q

Fiber characteristics:

A
  • high tensile strengths
  • high degrees of crystallinity
  • structures containing polar groups
125
Q

Polymers fibers are formed by

A

spinning:

  • extrude polymer through a spinneret (a die containing many small orifices)
  • the spun fibers are drawn under tension
  • leads to highly aligned chains - fibrillar structure
126
Q

Coatings

A

thin polymer films applied to surfaces – i.e., paints, varnishes

127
Q
  • protects from corrosion/degradation
  • decorative – improves appearance
  • can provide electrical insulation
A

Coatings

128
Q

bonds two solid materials

A

Adhesives (adherands)

129
Q

bonding types:

A

Secondary – van der Waals forces

Mechanical – penetration into pores/crevices

130
Q

produced by blown film extrusion

A

Films

131
Q

gas bubbles incorporated into plastic

A

Foams

132
Q

Limitations of polymers:

A
  • E, σy, Kc, T application are generally small.

- Deformation is often time and temperature dependent

133
Q

Thermoplastics (PE, PS, PP, PC):

A
  • Smaller E, σy, T application
  • Larger Kc
  • Easier to form and recycle
134
Q

Elastomers (rubber):

A
  • Large reversible strains
135
Q

Thermosets (epoxies, polyesters):

A
  • Larger E, σy, T application

- Smaller Kc

136
Q

Polymer Processing:

A

compression and injection molding, extrusion, blown film extrusion

137
Q

Combination of two or more individual materials

A

Composite

138
Q

What is the design goal of composites?

A

obtain a more desirable combination of properties (principle of combined action)

139
Q

Multiphase material that is artificially made

A

Composite

140
Q

Phase types:

A
  • Matrix - is continuous

- Dispersed - is discontinuous and surrounded by matrix

141
Q

Purposes of the matrix phase:

A
  • transfer stress to dispersed phase

- protect dispersed phase from environment

142
Q

Types matrix phase:

A

MMC, CMC, PMC (metal, ceramic, polymer)

143
Q

Dispersed phase:

– Purpose:

A

MMC: increase σy, TS, creep resist.
CMC: increase Kic ( fracture toughness)
PMC: increase E, σy, TS, creep resist

144
Q

Types of dispersed phase:

A

particle, fiber, structural

145
Q

Estimate fiber-reinforced composite modulus of elasticity for continuous fibers

A

Continuous fibers

146
Q
  • Continuous fibers pulled through resin tank to impregnate fibers with thermosetting resin
  • Impregnated fibers pass through steel die that preforms to the desired shape
  • Preformed stock passes through a curing die that is
  • -precision machined to impart final shape
  • -heated to initiate curing of the resin matrix
A

Pultrusion

147
Q
  • Continuous reinforcing fibers are accurately positioned in a predetermined pattern to form a hollow (usually cylindrical) shape
  • Fibers are fed through a resin bath to impregnate with thermosetting resin
  • Impregnated fibers are continuously wound (typically automatically) onto a mandrel
  • After appropriate number of layers added, curing is carried out either in an oven or at room temperature
  • The mandrel is removed to give the final product
A

Filament Winding

148
Q
  • stacked and bonded fiber-reinforced sheets
    - stacking sequence: e.g., 0º/90º
    - benefit: balanced in-plane stiffness
A

Laminates

149
Q

honeycomb core between two facing sheets

- benefits: low density, large bending stiffness

A

Sandwich panels

150
Q

Costs are not effected by the level of production

A

Fixed costs

151
Q

Includes both variable and semi-variable costs

A

Overhead costs

152
Q

costs that are directly affected by the level of production

A

Variable costs

153
Q

Variable costs

A

= UC = Total Unit Cost

154
Q

Variable costs that have a minimum fixed value and then a variable component that fluctuates with the production level

A

Semi-variable costs

155
Q

total income received from sales

A

Revenue

156
Q

Selling Price times number of units sold

A

Revenue

157
Q

the money you have after subtracting fixed and variable cost from the revenue

A

Profit BT

158
Q

the money you have after subtracting fixed and variable cost and Taxes from the revenue

A

Profit AT

159
Q

purchased material and lower level manufactured parts that include direct labor and overhead

A

Material

160
Q

Pay to employees who add value to product

Often paid hourly, or per item, but can be salaried

A

Direct Labor

161
Q

General term for all other variable costs that are NOT included in material and direct labor

A

Overhead (OH)

162
Q

labor paid for non value added work such as: moving & stocking material, quality inspection, unloading trucks, receiving material (both purchased and manufactured). Includes fringe benefits

A

Indirect labor

163
Q

for manufacturing and warehouse areas

A

Utilities

164
Q

paint, jigs & fixtures, cutting oils, maintenance supplies, shipping supplies not on BOM, bolts, nails, glue not on BOM, etc

A

Production Supplies

165
Q

shop/warehouse

A

Janitorial & maintenance Services

166
Q

A decision-making aid for determining whether a particular production or sales volume will result in losses or profits

A

Break-Even Analysis

167
Q

What is the break-even analysis used for?

A

Used to see if your income is more than your expense

Determine minimum price a product can be sold for

Determine the minimum quantity of sales

168
Q

How do you set a selling price?

A

Need to know the Unit Cost = M, L, OH

Determine the margin profit

169
Q

Based on competitive strategy

A

margin profit

170
Q

Based on who you are selling to

A

margin profit

171
Q
  • Technique for evaluating process and equipment alternatives
  • Objective is to find the point in dollars and units at which certain costs equals revenue
  • Requires estimation of fixed costs, variable costs, and revenue
A

Break-Even Analysis

172
Q

Revenue function begins at the _____ and proceeds ____ to the _____, increasing by the selling price of each unit

A

origin
upward
right

173
Q

Where the revenue function crosses the total cost line is the

A

break-even point

174
Q

What are the assumptions of a break-even analysis?

A
  • Costs and revenue are linear functions
  • -Generally not the case in the real world
  • We actually know these costs
  • -Although sometimes difficult to verify
  • Time value of money is often ignored
175
Q

Two basic approaches to Break-Even

A
  • Fixed time period with variable production rate

- Fixed production rate with variable time period

176
Q

The _________ is traditionally used

A

Fixed Time Period

177
Q

Four different Break-Even Points:

A
  • Shutdown Point
  • Break-Even at cost
  • Break-Even at required return
  • Break-Even at required return after taxes
178
Q

When the total revenue is equal to sum of variable and semivariable costs

A

Shutdown Point

179
Q

When the total revenue is equal to total costs (variable, semi-variable, and fixed)

A

Break-Even at cost

180
Q

When the total revenue is equal to the total costs plus the required return

A

Break-Even at required return

181
Q

When the total revenue is equal to the total costs plus the required return plus the taxes on the required return

A

Break-Even at required return after taxes

182
Q

Revenue (shutdown point) =

A

Variable costs + Semi-variable costs

183
Q

Revenue (Break-Even Analysis: At Cost) =

A

Total costs =Fixed costs + Variable costs +Semi-variable costs

184
Q

Revenue (At Required Return) =

A

Total cost + Required return

185
Q

Revenue (At Required Return) =

A

Fixed costs + Variable costs + Semi-variable costs + Required return

186
Q

Revenue (At Required Return After Tax) =

A

Total cost + Required return + Taxes on the required return

187
Q

General expression to determine material cost:

A

C(u) = C(w) x W

188
Q

C(u)

A

total unit cost, $

189
Q

C(w)

A

cost per unit weight, $/weight ($/kg, $/lb)

190
Q

W

A

weight (k,lb)

191
Q

Weight can be expressed by:

A

W = d x V

192
Q

d

A

density, weight/unit volume (kg/m^3, lb/in^3)

193
Q

V

A

volume (m^3, in^3) `

194
Q

Thus expression transforms to:

A

C(u) = C(w) x d x V

195
Q

Volume can be expressed by:

A

V = L x A

196
Q

L

A

design length (m, in)

197
Q

A

A

design cross-sectional area (m^2, in^2)

198
Q

Thus expression transforms to again:

A

C(u) = C(w) x d x L x A

199
Q

Cross-sectional area frequently involved in

A

basic design relationships

200
Q

Cross sectional area

A

usually determined by design requirements

201
Q

Two of the most common design requirements are:

A

1) The product must support a design load (strength requirement)
2) The product is to be restricted in the amount of deflection (stiffness requirement)

202
Q

Design relationships for cross-sectional area (A)

A

must be developed

203
Q

Design relationship for simple tension in a solid bar:

A

S = P/A or A = P/S

204
Q

S

A

material strength (MPa, kpsi)

205
Q

P

A

load (kN, lb)

206
Q

A

A

cross sectional area (m^2, in^2)

207
Q

Sometimes a design calls for materials when
COST is not critical for a solid rod, bar or cylinder
Examples would be:

A
  • Airplane / aerospace industry
  • Hospital equipment (implants use Titanium…)
  • Sports Equipment (bikes, carabiners…)
208
Q

For more complex loadings than simple tension the expression in return is

A

more complex

209
Q

In cases with multiple constraints (e.g., load AND elongation),

A

critical cross-sectional areas must be calculated

210
Q

Cost performance is only comparable for

A

same criteria (that is, loading)

211
Q

In cases where load is critical for one material and elongation for another ->

A

ratio should not be used

212
Q

What type(s) of bonds is (are) found between atoms within hydrocarbon molecules?

A

Covalent bonds

213
Q

How do the densities compare for crystalline and amorphous polymers of the same material that have identical molecular weights?

A

Density of crystalline polymer > density of amorphous polymer

214
Q

Significant tensile deformation of a semicrystalline polymer results in a highly-oriented structure (T or F)

A

True. Significant tensile deformation of a semicrystalline polymer results in a highly-oriented structure

215
Q

How does annealing an undeformed semicrystalline polymer affect its yield strength?

A

Annealing an undeformed semicrystalline polymer produces an increase in its tensile strength

216
Q

Which of the following factor(s) favor(s) brittle fracture in polymers?

  • Increasing in temperature.
  • Increasing in strain rate.
  • The presence of a sharp notch.
  • Decreasing specimen thickness.
A
  • Increasing strain rate
  • the presence of a sharp notch
  • decreasing temperature
217
Q

The bonding forces between adhesive and adherend surfaces are thought to be

  • Electrostatic
  • Covalent
  • Chemical
A

electrostatic

218
Q

Deformation of a semicrystalline polymer by drawing produces what?

A
  • an increase in strength in the direction of drawing

- a decrease in strength perpendicular to the direction of drawing

219
Q

How does deformation by drawing of a semicrystalline polymer affect its tensile strength?

A

increases the tensile strength

220
Q

How does increasing the degree of crystallinity of a semicrystalline polymer affect its tensile strength?

A

leads to an increase in its tensile strength. This is due to enhanced interchain bonding and forces in crystalline regions; in response to applied stresses, interchain motions become more restrained as degree of crystallinity increases

221
Q

How does increasing the molecular weight of a semicrystalline polymer affect its tensile strength?

A

The tensile strength of a semicrystalline polymer increases with increasing molecular weight. This effect is explained by the increased chain entanglements at higher molecular weights

222
Q

In order for a polymer to behave as an elastomer, what is necessary?

A

In order for a polymer to behave as an elastomer

  • It must not crystallize easily
  • Chain bond rotations must be relatively free
  • The polymer must be above its glass transition temperature
223
Q

A random and lightly crosslinked copolymer that has a glass-transition temperature of –40°C is an _______ since it is a random copolymer (i.e., is highly noncrystalline), is lightly crosslinked, and is above its glass transition temperature.

A

elastomer

224
Q

A branched and isotactic polypropylene that has a glass-transition temperature of –10°C is a __________ since it has a branched structure.

A

thermoplastic

225
Q

The polyethylene that has a glass-transition temperature of 0°C is a _________ since it is heavily crosslinked.

A

thermoset (nonelastomer)

226
Q

Linear polyvinyl chloride that has a glass-transition temperature of 100°C is a __________ since it has a linear structure.

A

thermoplastic

227
Q

What is the definition of glass transition temperature?

A

The glass transition temperature is the temperature at there is a slight decrease in slope of the temperature versus specific volume curve.

228
Q

There is a definite temperature at which a liquid transforms to a glassy (or noncrystalline) solid. (T or F)

A

False. Unlike crystalline materials, a glassy or noncrystalline material does not transform into a solid at a definite temperature. Rather, upon cooling from the liquid, a glass becomes more viscous as the temperature decreases.

IE 301 (3 decks)

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