Applied Dental Materials 2 Lecture 4 (Wrought Alloys)

Front 1

What the name for a cast alloy that is rolled thin, worked, pulled into a wire or bent and becomes stronger and harder?

Back 1

wrought alloy

Front 2

What are two common examples of wrought wire?

Back 2

ortho wire
RPD clasp wire

Front 3

True or false, wrought wire properties are virtually identical to cast alloy

Back 3

false

Front 4

The grains inwrought wire are (bunched/elongated), contain (very little/a lot) of distortion

Back 4

elongated, a lot

Front 5

"cold-working" takes place at what temperature?

Back 5

room temp (so it's somewhat of a misnomer)

Front 6

line defects and dislocations are known as (point/lattice) imperfections

Back 6

lattice

Front 7

Dislocations are (2/3) dimensional defects

Back 7

3

Front 8

What 3D defect is responsible for the peculiar mechanical properties exhibited by metals?

Back 8

dislocation

Front 9

What is the term for the linear array of atoms each of which has a coordination differing from the normal coordination of those atoms in the structure?

Back 9

dislocation

Front 10

The charge field around each metal atom is (different/the same), this allowing dislocation

Back 10

the same

Front 11

Impurities, atoms of (smaller/larger) size and grain boundaries act as obstructions and cause the dislocations to pile-up, resulting in (amplified/impaired) dislocation movement, which eventually distorts the grain and results in the (softening/hardening) of the metal if it is stressed more. This process is called ____

Back 11

larger, impaired, hardened, strain-hardening (or work-hardening, cold-working)

Front 12

What are two other terms for strain-hardening?

Back 12

work-hardening
cold-working

Front 13

(Large/small) grains are stronger because they have (more/less) dislocation barriers

Back 13

small, more

Front 14

Small grains can be defined as (fine/coarse)

Back 14

fine

Front 15

Twinning occurs at (high/low) strain rates and (high/low) temp

Back 15

high, low

Front 16

Atoms have mirror orientation relationship with each other in metals with relatively few slip systems is referred to as ___

Back 16

twinning

Front 17

What is the reversal of the effects associated with cold-working by heating the metal to an appropriate elevated temp?

Back 17

annealing

Front 18

Annealing is the reversal of the effects associated with what?

Back 18

cold working

Front 19

What is the stage at which cold-work properties disappear, no significant microscopic change, and has residual stress?

Back 19

recovery

Front 20

What is the term for the change in microstructure, new strain-free grains in areas of severe cold-work (grain boundaries) or severe deformation; ductile

Back 20

recrystallization

Front 21

What is the stage where there is growth of fine grains to larger coarse grains?

Back 21

grain growth

Front 22

What are the 3 stages of annealing?

Back 22

recovery, recrystallization, grain growth

Front 23

Say whether TENSILE STRENGTH and DUCTILITY increase or decrease during these 4 stages:

cold-working
recovery
recrystallization
grain growth

Back 23

cold-working (D decrease, TS increase)
recovery (D same, TS decrease)
recrystallization (D increase, TS decrease)
grain growth (D increase, TS decrease)

Front 24

At which phase of annealing are Tensile strength and ductility BOTH increasing? Both decreasing?

Back 24

None! Always going in opposite directions (except recovery where ductility does not change)

Front 25

Compared to cast alloy, wrought metals:

(higher/lower) elastic modulus
(higher/lower) plastic deformation (aka ductility in cast alloy)
(higher/lower) flexibility
(higher/lower) yield strength and hardness
(elongated/compressed) grains

Back 25

UNCHANGED (elastic modulus is = in WW and CA), lower, higher, higher, elongated

Front 26

Optimal ortho wire produces (heavy/light) and (variable/continuous) force

Back 26

light, continuous

Front 27

It is critical that ortho wires (do/do not) decrease rapidly and decay away

Back 27

do NOT

Front 28

List these in the proper order of creating archwire:

heat treatment to eliminate work-hardening of wires

mechanical reduction of cross-section for drawing of round wire

casting of ingot

mechanical reduction of round wire by rollers to produce rectangular wires (w/slight rounding of edges)

Back 28

ingot, mechanical reduction of cross-section, mechanical reduction of round wire, heat treatment

Front 29

There was a whole "duh" slide about how there is archwire variety and that orthodontists need to know the properties, etc...

Back 29

move along

Front 30

Elastic range is also called ___ range

Back 30

working

Front 31

What is the distance a wire will bend elastically before permanent deformation occurs?

Back 31

elastic range

Front 32

Permanent deformation occurs at a metals ___ limit

Back 32

proportional

Front 33

The distance the wire will deform plastically before it fractures is called the ___ range

Back 33

plastic

Front 34

Between proportional limit and fracture is known as the ___ range

Back 34

plastic

Front 35

You bend an archwire to which one?

The form you want the teeth to have

The form the teeth currently have

Back 35

The form you want the teeth to have

Front 36

If lots of force is used in friction of the wire, it will results in (more/less) force to actually move the teeth

Back 36

less

Front 37

Amount of deformation recovery, upon unloading, beyond the proportional limit is called

Back 37

springback

Front 38

YS/E or PL/E is called

Back 38

springback

Front 39

more springback, (more/less) deformation wire can undergo and then recover from

Back 39

more

Front 40

pseudoelasticity is also called ___

Back 40

superelasticity

Front 41

What types of wires can undergo superelasticity?

Back 41

Ni-Ti

Front 42

Ni-Ti undergo ___-induced transformation to high-stress martensitic Ni-Ti phase by work-hardening mechanism

Back 42

stress

Front 43

You heat a Ni-Ti wire and heat it to 480C and give wire ideal arch form... then allow it to cool to room temperature and then place the wire in the patients mouth (25-27C) returns wire to what it was when it was originally heated. This phenomenon is called:

Back 43

shape memory

Front 44

In shape memory, the wire is heated to a high temperature, cooled and heated back to the same initial high temperature

Back 44

False! High temp, low temp, slightly higher temp

Front 45

4 main compositions of ortho wire are

Back 45

stainless steel
Co-Cr
Ni-Ti
Beta-Ti

Front 46

What is the ONLY kind of stainless steel wire used in ortho?

Back 46

austenitic

Front 47

What are the three kinds of stainless steel wire?

Back 47

ferritic, martensitic, austenitic

Front 48

What are the 4 subclasses of Co-Cr wire?

Back 48

soft
ductile
semi-resilient
resilient

Front 49

What are the 3 subclasses of Ni-Ti wire?

Back 49

conventional (non-superelastic)
pseudoelastic
thermoelastic

Front 50

How many subclasses of Beta-Ti wire are there?

Back 50

None! Bye!

Front 51

Austenitic is AISI __ and ___, or ___ (all numbers)

Back 51

302, 304, 316L

Front 52

Which type of stainless steel wire is not used in ortho but is used as surgical instrumentation?

Back 52

martensitic

Front 53

Austenitic wire 302 and 304 is for ___ wire while 316L is for ___

Back 53

ortho; low C (carbon) concentration, implants, brackets, etc.

Front 54

Which type of stainless steel is MOST corrosion resistant?

Back 54

austenitic

Front 55

Ferritis and Martensitic stainless steel are AISI # ____

Back 55

400

Front 56

Martensitic stainless steel has:

(high/low) strength and hardness
(high/low) ductility
(high/low) corrosion resistance
(is/is not) heat treatable

Back 56

high, low, low, is

Front 57

In an 18-8 wire, what do these #s mean?

Back 57

18 = 18 wt% Cr

8 = 8 wt% Ni

Front 58

What are the approximate concentrations of Fe, Cr, Ni, and C in austenitic 18-8 stainless steel wire?

Back 58

70%, 18%, 8%, 0.15% or 0.08%

(spec 302 = 0.15% whereas spec 304 = 0.08%)

Front 59

Austenitic 18-8 SS wire has:

(high/low) elastic modulus
(high/low) stiffness
(high/low) ductility
(good/poor) in ability to overcome sensitization

Back 59

high, high, high, good

Front 60

Austenitic 18-8 SS wire has:

(good/poor) joinability with soldering
(good/poor) formability
(good/poor) corrosion resistance

Back 60

All 3 are GOOD

Front 61

Austenitic 18-8 SS wire has:

(higher/lower) springback than newer wire
(high/low) bracket friction

Back 61

lower, low

Front 62

True or False, Austenitic 18-8 SS wire releases Ni

Back 62

True

Front 63

True or False, Austenitic 18-8 SS wire is available in only 1 cross section geometry due to it's difficult handling properties

Back 63

False, available in many different cross sections

Front 64

Austenitic 18-8 SS wire is heat treated between __ and __ C to minimize breakage be eliminating residual stress

Back 64

400-500

Front 65

What is the process of precipitation of Cr3C in grain boundaries at temps above ___C leading to loss of passivation, decreased resistance to corrosion, and partial disintegration

Back 65

sensitization, 400

Front 66

Addition of an element that will precipitate as a carbide in the preference to Cr is called

Back 66

stabilization

Front 67

Twisting or braiding a wire leads to (lower/higher) EM, this making the wire (more/less) stiff

Back 67

lower, less

Front 68

Co-Cr wires have properties that are:

a. similar to SS wire
b. much worse than SS wire
c. much better than SS wire
d. identical to SS wire

Back 68

a. similar to SS wire

Front 69

What are the % compositions of the following elements in Co-Cr wire?

Co, Cr, Fe, Ni, Mo, Mn, C, Be

Back 69

Co 40, Cr 20, Fe 15.8, Ni 15, Mo 7, Mn 2, C 0.15, Be 0.04

Front 70

Rank these colors of Co-Cr wire from hardest to softest:

red, blue, yellow, green

Back 70

Red
Green
Yellow
Blue

(Mnemonic: Run and Get Your Burs)

Front 71

Co-Cr wires have:

(good/bad) formability
(higher/lower) springback than newer wires
(higher/lower) EM than SS wire

Back 71

good, lower, same (wasn't an option... now you won't forget!)

Front 72

Co-Cr can be heat treated at ___C to increase stiffness and torsional strength

Back 72

500

Front 73

Co-Cr wires have:

(good/poor) corrosion resistance
(high/low) bracket to wire friction levels
(is/is not) joinable with soldering

Back 73

good, low, is

Front 74

Ni-Ti wires have what % of Ni, Ti and Co?

Back 74

Ni 52, Ti 45, Co 3

Front 75

Ni-Ti wires have:

(good/poor) springback and flexibility
(true/pseudo) shape memory
(low/high) EM compared to SS wire

Back 75

good, true, low (in fact, only 20% of that of SS wire!)

Front 76

Ni-Ti wires have:

(higher/lower) frictional forces compared to steel alternatives
(good/poor) formability and joinability
heat treatment at __-__C

Back 76

higher, poor, 500-600

Front 77

Which type of wire allows for "variable-modulus" orthodontics?

Back 77

Ni-Ti

Front 78

What type of wire is best in a highly curved root canal?

Back 78

Ni-Ti, bc of its low EM

Front 79

Beta-Ti wires have what % composition of Ti, Mo, Zr, Sn

Back 79

Ti 77, Mo 11, Zr 6, Sn 4

Front 80

Some new versions of Beta-Ti wires have a __+ ion added

Back 80

N

Front 81

Beta-Ti wires have:

(higher/lower) EM than SS wire
(high/low) ductility
(high/low) springback)
(good/poor) formability

Back 81

lower, high, high, good

Front 82

What is the ONLY wire possessing true weldability?

Back 82

Beta-Ti

Front 83

True or False, you should not heat-treat Beta-Ti wires

Back 83

true

Front 84

True or False, Beta-Ti wires contain the most Ni of the 4 wires

Back 84

False, NO Ni at all!

Front 85

Beta-Ti wires have:

(high/low) bracket to wire friction due to a (smooth/rough) surface

Back 85

high, rough

Front 86

Rank the 4 wires in order from highest to lowest in terms of EM (elastic modulus)

Back 86

Co-Cr
SS
Beta-Ti
Ni-Ti

Front 87

Rank the 4 wires in order from highest to lowest in terms of yield strength

Back 87

SS
Co-Cr
Beta-Ti
Ni-Ti

Front 88

Rank the 4 wires in order from highest to lowest in terms of stiffness

Back 88

Co-Cr
SS
Beta-Ti
Ni-Ti

Front 89

Rank the 4 wires in order from highest to lowest in terms of ductility

Back 89

SS and Beta-Ti are tied
Ni-Ti = "poor"
Co-Cr = "low"

Front 90

Rank the 4 wires in order from difficult to easy in terms of ease of soldering

Back 90

Ni-Ti
Beta-Ti
Co-Cr = reasonable/moderate
SS = reasonable

Front 91

Ticonium is an alloy of what 4 metals?

Back 91

Co-Cr-W-Ni

Front 92

Co-Cr-W-Ni make up the alloy known as ___

Back 92

ticonium

Front 93

Retention pins are usually made of what type of wire as well as Ti and Ti alloys?

Back 93

18-8 SS

Front 94

How is the cutting edge of an endo file created?

Back 94

by twisting a wire blank

Front 95

Rotary Ni-Ti are (nonsuperelastic/superelastic)

Back 95

superelastic

Front 96

The old technique was to use (superelastic/nonsuperelastic) Ni-Ti endo files by hand

Back 96

nonsuperelastic

Front 97

The superelastic plateau region of the graph is from point __ to __ (letters) a

Back 97

b to c