Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MAT SCI 298 > Lecture 7 - Nickel Alloys > Flashcards

Lecture 7 - Nickel Alloys Flashcards

1
Q

What is chromium’s effect on nickel?

A

oxidation and hot corrosion resistance, solid-solution strengthening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is molybdenum and tungsten’s effect on nickel?

A

solid solution strengthening, M6C carbides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is aluminum and titanium’s effect on nickel?

A

forms gamma’ hardening precipitate; Al enhances oxidation resistance and Ti forms MC carbides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is cobalt’s effect on nickel?

A

raises gamma’ solvus temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is boron, zirconium, and hafnium’s effect on nickel?

A

improves rupture life through increased ductility
B forms borides
Hf forms MC carbides and promotes eutectic gamma-gamma’ formation in cast alloys

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is carbon’s effect on nickel?

A

forms MC, M7C3, M23C6, M6C carbides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is niobium’s effect on nickel?

A

forms gamma’, Ni3Nb, hardening precipitate; forms delta orthorhombic Ni3Nb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is tantalum’s effect on nickel?

A

solid solution strengthening; forms MC carbides, enhances oxidation resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the microstructures of manufactured Inconel alloys like?

A

complex and messy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why is post-processing treatment necessary?

A

since it is difficult to control the phase fraction of as-built materials, the microstructure has poor properties and HIPing is needed to tailor material properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which properties are critical for Inconel alloys?

A

fatigue and creep at elevated temperatures (porosity is a big concern)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What do the macro and micro residual stresses affect for printing Inconel 718?

A

Type I - part dimensional accuracy
Type II - mechanical properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the difference between Inconel 625 and 718?

A

625 - solid-solution matrix-stiffened face-centered-cubic-alloy
718 - age-hardenable austenitic material, strength dependent on precipitation of gamma prime during heat treatment, higher value, adds niobium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are topologically close-packed phases?

A

phases formed by high levels of refractory elements to increase high temperature creep and rupture properties
undesirable brittle phases formed during heat treatment or service
appear as discs and are easy crack origins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What phases do TCP’s include?

A

sigma (Fe-cr, 50-50) the worst phase for ductility
mu
Laves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the Ni3Al?

A

gamma’, geometrically close-packed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are properties of Inconel 625?

A

melt point 1300C
thermal expansion coefficient of 1.28 10^-5/K
resists wide range of temperature extremes

18
Q

What are applications for Inconel 625?

A

marine, aerospace, nuclear, industrial components

19
Q

What are applications for Inconel 718?

A

jet engine, gas turbine

20
Q

What are the current approaches to print 718?

A

L-PBF
L-DED
EB-DED
EB-PBF
Binder Jet

21
Q

How high is the rupture strength for SLM alloys?

A

low

22
Q

Why add Al to Ni?

A

Reduce weight

23
Q

How can you control hardness with aging?

A

aim for peak aging (not over or under)

24
Q

What are the two more important properties for elevated temperatures for Ni?

A

mechanical strength, creep

25
Q

What is the typical application temperature for Ni?

A

600-700C

26
Q

What is the relationship between gamma’ and creep rupture strength, and temperature?

A

creep rupture strength increases with gamma’
creep rupture strength decreases with temperature

27
Q

Why is there a push to increase temperature limit for Ni alloys?

A

higher temperature limit -> higher operating temperature -> higher efficiency

28
Q

What are the factors of the harsh operating environment?

A

high temperature, high stress, high oxidation

29
Q

Why is Inconel 625 relatively easy to print?

A

no phase transformation, but some voids

30
Q

What is the Laves phase

A

extremely brittle

31
Q

What is a TTT diagram?

A

time temperature transformation that shows the phases transformed into based on operating temperature over time

32
Q

Can you heat treat or add precipitates to Inconel 625?

A

no

33
Q

Which is easier to print?

A

625

34
Q

Why does porosity present an issue for 718?

A

Since applications are thin, need to control precision

35
Q

Do laves phase and needle-like delta phase make the metal stronger?

A

yes - unless there are cracks

36
Q

Do we want grain boundaries for IN718?

A

No

37
Q

What limits ductility?

A

micro cracks, voids

38
Q

What is HIP?

A

Hot isostatic pressing

39
Q

What does an enhanced ductility after processing mean?

A

lots of pores initially

40
Q

Why do SLM 718 have poor fatigue properties?

A

porosity

MAT SCI 298 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions