Type Analysis
|
Element |
Min |
Max |
|
Carbon |
-- |
0.10 |
|
Nickel |
Bal. |
|
Chromium |
20.0 |
23.0 |
|
Iron |
-- |
5.00 |
|
Silicon |
-- |
0.50 |
|
Manganese |
-- |
0.50 |
|
Sulfur |
-- |
0.015 |
|
Phosphorus |
-- |
0.015 |
|
Molybdenum |
8.00 |
10.0 |
|
Titanium |
-- |
0.40 |
|
Cobalt |
-- |
1.00 |
|
Columbium + Tantalum |
3.15 |
4.15 |
|
Aluminum |
-- |
0.40 |
Description
Alloy 625 is a nonmagnetic , corrosion - and oxidation-resistant, nickel-based alloy. Its outstanding strength and toughness in the temperature range cryogenic to 2000°F (1093°C) are derived primarily from the solid solution effects of the refractory metals, columbium and molybdenum, in a nickel-chromium matrix. The alloy has excellent fatigue strength and stress-corrosion cracking resistance to chloride ions. Some typical applications for alloy 625 have included heat shields, furnace hardware, gas turbine engine ducting, combustion liners and spray bars, chemical plant hardware, and special seawater applications.
Corrosion Resistance
Alloy 625 has withstood many corrosive environments. In alkaline, salt water, fresh water, neutral salts, and in the air, almost no attack occurs. The nickel and chromium provide resistance to oxidizing environments. Nickel and molybdenum provide for resistance to nonoxidizing atmospheres. Pitting and crevice corrosion are prevented by molybdenum. Niobium stabilizes the alloy against sensitization during welding. Chloride stress-corrosion cracking resistance is excellent. The alloy resists scaling and oxidation at high temperatures.
Physical Properties
|
Physical Property |
°C |
Metric Units |
°F |
British Units |
|
Density |
22 |
8.44 g/cubic cm |
72 |
0.305 lb/cubic in. |
|
Electrical
Resistivity |
23
100
200
300
400
500
600 |
1.26 microhm-m
1.27
1.28
1.29
1.30
1.31
1.32 |
74
212
392
572
752
932
1112 |
49.6 microhm-in.
50.0
50.4
50.8
51.2
51.6
52.0 |
|
Mean Coefficient
of Thermal
Expansion |
20-204
20-316
20-427
20-538
20-649
20-760
20-871
20-982 |
13.1 x 10(-6)m/m-°C
13.5
13.9
14.4
15.1
15.7
16.6
17.3 |
68-400
68-600
68-800
68-1000
68-1200
68-1400
68-1600
68-1800 |
7.3 microinches/in.-°F
7.5
7.7
8.0
8.4
8.7
9.2
9.6 |
|
Thermal
Conductivity |
23
100
200
300
400
500
600 |
9.8 W/M-°C
11.4
13.4
15.5
17.6
19.6
21.3 |
74
212
392
572
752
932
1112 |
68 Btu-in./ft².-hr.-°F
79
93
108
122
136
148 |
|
Specific
Heat |
0
100
200
300
400
500
600 |
429 J/kg-°C
446
463
480
496
513
560 |
32
212
392
572
752
932
1112 |
0.102 Btu/lb-°F
0.107
0.111
0.115
0.118
0.123
0.134 |
Average Dynamic Modulus of Elasticity *
|
Form |
Condition |
Test Temp.,
F(C) |
Average Dynamic Modulus of
Elasticity, psi x 10(6) (MPa) |
|
Plate,
3/8 in. (9.5 mm)
thick |
Annealed at
1925°F (1052°C),
rapid cooled |
Room
200 (93)
400 (204)
600 (316)
800 (427)
1000 (538)
1200 (649)
1400 (760)
1600 (871)
1800 (982) |
30.2 (208,000)
29.2 (201,000)
28.8 (199,000)
27.7 (191,000)
26.7 (184,000)
25.6 (176,000)
24.3 (168,000)
22.8 (157,000)
21.2 (146,000)
18.7 (129,000) |
* Average of five tests at each temperature.
Mechanical Properties
Average Impact Strength, Plate *
|
Aging Temperature,
F (C) |
Aging Time, hrs. |
Average Charpy V-Notch
Impact Strength, |
|
ft. lbs. |
J |
|
Annealed** |
-- |
81 |
110 |
|
1200 (649) |
1000
4000
8000
16000 |
11
8
5
4 |
15
11
7
5 |
|
1400 (760) |
1000
4000
8000
16000 |
5
4
5
4 |
7
5
7
5 |
|
1600 (871) |
1000
4000
8000
16000 |
12
11
15
14 |
16
15
20
19 |
Average Hardness and Tensile Data, Room Temperature
|
Condition |
Form |
Ultimate
Tensile
Strength,
ksi (MPa) |
Yield
Strength
at 0.2%
offset,ksi (MPa) |
Elongation
in 2"
percent |
Hardness,
Rockwell |
|
Annealed at
1925°F (1052°C),
rapid cooled |
Sheet
0.014-0.063"
thick |
132.0 (910) |
67.9 (468) |
47 |
B94 |
|
Annealed at
1925°F (1052°C),
rapid cooled |
Sheet,*
0.0.78-0.155"
thick |
131.5 (907) |
67.4 (465) |
45 |
B97 |
|
Annealed at
1925°F (1052°C),
rapid cooled |
Plate,***
1/4"
1/2"
3/4"
1.00"
1-1/2"
1-3/4" |
132.0 (910)
130.0 (896)
132.3 (912)
127.2 (877)
127.3 (878)
128.0 (883)
|
65.5 (452)
67.0 (462)
80.0 (552)
75.3 (519)
73.7 (508)
66.0 (455)
|
46
44
44
42
43
44
|
B94
B98
B98
B97
B97
C20
|
Average Tensile Data, Room Temperature*
|
Form |
Aging Temperature,
F (C) |
Aging Tme, hrs. |
Ultimate
Tensile
Strength,
Ksi (MPa) |
Yield
Strength
at 0.2%
offset,
Ksi (MPa) |
Elongation
in 2 in.,
(50.8 mm),
percent |
|
Plate,
1/2 in. (12.7 mm)
thick |
Annealed** |
-- |
127.7 (880) |
66.2 (456) |
46 |
|
1200 (649) |
1000
4000
8000
16000 |
165.0 (1138)
163.6 (1128)
164.2 (1132)
165.4 (1140) |
122.3 (843)
117.9 (813)
117.8 (812)
118.5 (817) |
28
24
18
12 |
|
1400 (760) |
1000
4000
8000
16000 |
142.9 (985)
145.5 (1003)
142.6 (983)
140.4 (968) |
95.5 (658)
104.1 (718)
97.4 (672)
96.1 (663) |
17
12
13
12 |
|
1600 (871) |
1000
4000
8000
16000 |
130.0 (896)
130.0 (896)
127.0 (876)
128.4 (885) |
68.3 (471)
66.4 (458)
63.7 (439)
63.4 (437) |
30
29
26
32 |
*Average of three tests from a single heat.
**1875F (1024C), rapid cooled.
Average Tensile Data, Sheet*
|
Test
Temperature,
°F(°C) |
Ultimate
Tensile
Strength,
ksi (MPa) |
Yield
Strength
at 0.2%
offset,ksi (MPa) |
Elongation
in 2"
percent |
|
Room
200
400
600
800
1000
1200
1400
1600
1800
2000 |
138.8 (957)
133.3 (919)
129.4 (892)
125.6 (866)
122.2 (843)
119.9 (827)
119.6 (825)
88.4 (609)
52.1 (359)
25.0 (172)
13.3 (92) |
72.0 (496)
67.3 (464)
62.2 (429)
59.5 (410)
59.2 (408)
58.8 (405)
57.0 (393)
55.3 (381)
34.9 (241)
10.8 (75)
6.1 (42) |
38
41
44
45
45
46
47
70
69
108
89 |
*Annealed at 1925°F (1052°C), rapid cooled
Heat Treatment
Alloy 625 has three basic heat treatments:
(1)High Solution Anneal - 2000/2200°F (1093/1204°C), air quench or faster.
(2)Low Solution Anneal - 1700/1900°F (927/1038°C), air quench or faster.
(3)Stress Relieve - 1650°F (899°C), air quench.
The time at the above temperatures depends on volume and section thickness. Strip, for example, would require shorter times than large sections. Temperatures for treatments No. 1 and 2 are generally held for 1/2 to 1 hour, 1 to 4 hours for treatment No. 3.
Treatment No. 1 is not commonly used for applications below 1500°F (816°C). It is generally used above 1500°F and where resistance to creep is important. The high solution anneal is also used to develop the maximum softness for mild processing operations such as cold rolling or drawing.
Treatment No. 2 is the used treatment and develops an optimum combination of tensile and rupture properties from ambient temperatures to 1900°F (1038°C). Ductility and toughness at cryogenic temperatures are also very good.
Treatment No. 3 is recommended for application below 1200°F (649°C) when maximum fatigue, hardness, tensile and yield strength properties are desired. Ductility and toughness at cryogenic temperatures are excellent. When a fine grain size is desired for fatigue, tensile and yield strengths up to 1500°F (816°C), treatment No. 3 is sometimes used. |
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