Module 8 (High Temp 500F) Flashcards

1
Q
Strain Aging
affected material (2)
A
  1. old CS

2. C-1/2Mo

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2
Q

Strain Aging

occur at what temp?

A

intermediate temp

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3
Q

Strain Aging

____ is not susceptible and with ____ aluminum

A
  1. fully killed stelled
    /
    sufficient aluminum (>0.015 wt%)
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4
Q

Strain Aging

appearance?

A

most likely NOT found until fracture

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5
Q
Strain Aging
prevention (3)
1. minimizing by \_\_\_\_ vs \_\_\_\_
2.\_\_\_\_\_\_ weld repair will eliminate effect of strain aging
3. \_\_\_\_\_when PWHT is no possible
A
  1. pressurization sequence vs temp
  2. PWHT weld repair will eliminate effect of strain aging
  3. Butter when PWHT is no possible
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6
Q

Strain Aging

inspection?

A

not used to control strain aging

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7
Q

Strain Aging

related mech?

A

blue brittle fracture

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8
Q

885F embrittlement

high____ % ____becomes embritted?

A

Cr and Ferrite

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9
Q

885F embrittlement

is a ______change

A

metallurgical

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10
Q

885F embrittlement

critical factor?

A
  1. alloy composition
  2. chrome content
  3. ferrite phase
  4. temperature
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11
Q

885F embrittlement

damage is _____,

A

cumulative

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12
Q

885F embrittlement

more exposure time is needed on _____% CR than at higher ______% Cr

A

13 % / 27%

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13
Q

885F embrittlement

occurs at _______F and what happen below and above F?

A

885F , need more time to reach max embrittle

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14
Q

885F embrittlement

effect on toughness is -____ pronounced at operating temp, but at lower temp during SD / SU

A

not

same as temper / sigma for 500F

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15
Q

885F embrittlement

duplex temp ____ for ____Time period?

A

600F / extended

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16
Q

885F embrittlement

identified by an ____in hardness

A

increase

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17
Q

885F embrittlement

most positive indicator?

A

impact testing

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18
Q

885F embrittlement

410SS reversed at what temp

A

350F

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19
Q

885F embrittlement

prevention? (2)

A
  1. avoid exposing the material at the temp range

2. use a non susceptible material

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20
Q

885F embrittlement
can be ________with HT but will embrittle ____
at what temp?

A

reversed / faster

1100F

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21
Q

885F embrittlement

inspection?

A
  1. difficult to located

2. impact or bend or sample?

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22
Q

885F embrittlement

related mech?

A

sigma phase embrittlement

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23
Q

sigma phase embrittlement

precipitation of a brittle compound of (3)

A
  1. Fe
  2. Cr
  3. Mo
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24
Q

sigma phase embrittlement

precipitation increase with (2)

A

Cr and Mo content

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25
Q

sigma phase embrittlement

temp range?

A

1000-1750F

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26
Q

sigma phase embrittlement

what is immune?

A

cold work nickle

27
Q

sigma phase embrittlement
affect material (2)
1. ____% of FE
2. _____% Cr

A
  1. 10-40% fe

2. >17% Cr

28
Q
sigma phase embrittlement
critical factors (4)
A
  1. time
  2. temp
  3. alloy composition
  4. degree of cold work
29
Q

sigma phase embrittlement

normally a _____time is required to form sigma

A

Long

30
Q

sigma phase embrittlement
sigma has formed during _____of SS, which take a period of hours

can form in hot wall _____ reactor that operate at high temps

A
  1. PWHT
31
Q

sigma phase embrittlement
allows with sigma can normally with normal operating stress but upon cooling to _____F may show lack of fracture toughness

A

500F (same as temper / 885 but not 500)

32
Q

sigma phase embrittlement

appearnace?

A

not readily apparent

33
Q

sigma phase embrittlement

inspection?

A

metallography or impact test or sample test

34
Q

sigma phase embrittlement

reversed condition

A

anneal 1950F for 4 hours

35
Q

Brittle Fracture

affected material?

A

CS / low alloys / 400SS

36
Q
Brittle Fracture 
critical factor (2)
A
  1. temp

2. material of construction

37
Q

Brittle Fracture

occurs most often? (3)

A
  1. during s/D and S/U
  2. thick walled
  3. auto refrigeration
38
Q

Brittle Fracture

appearance

A

straight and non branching

39
Q

Brittle Fracture

prevention ? What metal to use? Condition? when not to hydro?

A

a. fully killed fine grain steel with austenite grain size finer than 6
b. control operating conditions
c. not hydro at low temps

40
Q

Brittle Fracture
inspection method?
aware of what?

A

not normally use to detect but aware of susceptible equipment can help prevent future damage

41
Q
Brittle Fracture 
relate mech (5)
A
  1. temper
  2. strain age
  3. 885F
  4. titanium hydrding
  5. sigma embrittlement
42
Q

Creep and stress rupture

Description?

A

high temp , metal slowly, and continuously deform

43
Q

Creep and stress rupture

affected material

A

all metals and alloys

44
Q

Creep and stress rupture

critical factor? (3)

A
  1. strength
  2. stress
  3. operating temp (metal)
45
Q

Creep and stress rupture

increase of ____ temp/ ___% of pressure will reduce the remaining life

A

25F or 15% pressure

46
Q

Creep and stress rupture
affected units? (2)

  1. ____ due to thermal stress
  2. _____ ductility failure have occurred in _____and high stress area in_____(metal) CRU
A
  1. DMW due to thermal stress

2. low creep ductility failure have occurred in wed HAZ and high stress area in 1.25-.5M CRU

47
Q
Creep and stress rupture
function of ? (3)
A
  1. load
  2. temperature
  3. stress
48
Q

Creep and stress rupture

affected equipment? (3)

A
  1. furnace
  2. boiler heaters
  3. hydro process reactor due to localized overheating due to h2 quench
49
Q

Creep and stress rupture?

appearance? (2)

A
  1. fishmouth

2. bulging / localized

50
Q

Creep and stress rupture?

inspection? (3)

A
  1. hard to see
  2. thermography for monitor
  3. bulging or sagging
51
Q

Ti hydriding

description

A

hydrogen diffusing into Ti and make it brittle

52
Q

Ti hydriding

critical factors? (3)

A
  1. temp
  2. solution chemistry
  3. alloy
53
Q

Ti hydriding

what else can promote damage?

A

galvanic corrosion

54
Q

Ti hydriding

inspection? (5)

A
  1. metallogrpahy
  2. hammer
  3. bend test
  4. crush test
  5. ECT
55
Q

Ti hydriding

____material that can combust in the presence of heat and o2

A

TI is a reactive

56
Q

Ti hydriding

related mech?

A

form of HE and could result in brittle fracture

57
Q

Ti hydriding

affect equipment?

A

sour water operating >165F

58
Q

Strain aging can also occur when welding in the vicinity of ______ in a susceptible material.

A

cracks and notches

59
Q

Formation of sigma phase in austenitic stainless steels can also occur in a few hours, as evidenced by the known tendency for sigma to form if an austenitic stainless steel is subjected to a postweld heat treatment at _____

A

1275°F

60
Q

Sigma phase in welds can be minimized by controlling ferrite in the range of______for Type 347 and somewhat less ferrite for Type 304.

A

5% to 9%

61
Q

Brittle Fracture

best way to detect brittle fracture?

A

Inspection is not normally used to mitigate brittle fracture.

62
Q

Brittle Fracture

Use material specifically designed for ___temps per ASME B&PV and what year???

A

low / 1987

63
Q

Brittle Fracture

hydro test is prone to BF because of (2)

A

high stress and low toughness