HAYNES® 625 alloy
Principal Features
Excellent Strength Up To 1500°F (816°C), Good Oxidation Resistance, and Good Resistance to Aqueous Corrosion
HAYNES® 625 alloy (UNS N06625) is a nickel- chromium-molybdenum alloy with excellent strength from room temperature up to about 1500°F (816°C). At higher temperatures, its strength is generally lower than that of other solid-solution strengthened alloys. Alloy 625 has good oxidation resistance at temperatures up to 1800°F (982°C) and provides good resistance to aqueous corrosion, but generally not as effectively as modern HASTELLOY® corrosion- resistant alloys.
Easily Fabricated
HAYNES® 625 alloy has excellent forming and welding characteristics. It may be forged or otherwise hot-worked providing temperature is maintained in the range of about 1800 to 2150°F (982 to 1177°C). Ideally, to control grain size, finish hot working operations should be performed at the lower end of the temperature range. Because of its good ductility, alloy 625 is also readily formed by cold working. However, the alloy does work-harden rapidly so intermediate annealing treatments may be needed for complex component forming operations.
In order to restore the best balance of properties, all hot- or cold-worked parts should be annealed and rapidly cooled.
The alloy can be welded by both manual and automatic welding methods, including gas tungsten arc (GTAW), gas metal arc (GMAW), electron beam, and resistance welding. It exhibits good restraint welding characteristics.
Heat Treatment
Unless otherwise specified, wrought HAYNES® 625 alloy is normally supplied in the mill-annealed condition. The alloy is usually mill-annealed at 1925°F plus or minus 25°F (1052°C plus or minus 14°C) for a time commensurate with section thickness and rapidly cooled or water-quenched for optimum properties. Depending on customer requirements, alloy 625 may also be supplied solution heat-treated at temperatures at or above 2000°F (1093°C), or mill annealed at temperatures below 1925°F (1052°C). Lower temperature mill annealing treatments may result in some precipitation of second phases in alloy 625 which can affect the alloy’s properties.
Applications
HAYNES® 625 alloy is widely used in a variety of high- temperature aerospace, chemical process industry, and power industry applications. It provides excellent service in short- term applications at temperatures up to approximately 1500°F (814°C); however, for long-term elevated temperature service, use of alloy 625 is best restricted to a maximum of 1100°F (593°C). Long-term thermal exposure of alloy 625 above 1100°F (593°C) will result in significant embrittlement. For service at these temperatures, more modern materials, such as HAYNES® 230® alloy, are recommended.
As a low-temperature corrosion-resistant material, alloy 625 has been widely used in chemical process industry, sea water, and power plant scrubber applications. However, in most current requirements it has largely been superseded by more capable HASTELLOY® alloys, such as C-22® and G-30® alloys.
*Please contact our technical support team if you have technical questions about this alloy.
Nominal Composition
| Weight % | |
| Nickel | 62 Balance |
| Cobalt | 1 max. |
| Iron | 5 max. |
| Chromium | 21 |
| Molybdenum | 9 |
| Niobium* + Tantalum | 3.7 |
| Manganese | 0.5 max. |
| Silicon | 0.5 max. |
| Aluminum | 0.4 max. |
| Titanium | 0.4 max. |
| Carbon | 0.1 max. |
*Also known as Columbium
Tensile Properties
Cold-Rolled and 1925°F (1052°C) Mill-Annealed, Sheet
| Test Temperature | 0.2% Yield Strength | Ultimate Tensile Strength | Elongation | |||
| °F | °C | ksi | MPa | ksi | MPa | % |
| RT | RT | 71.2 | 491 | 133.9 | 923 | 47.5 |
| 1000 | 538 | 56.3 | 388 | 118.4 | 816 | 54.2 |
| 1200 | 649 | 55.1 | 380 | 117.7 | 811 | 109.3 |
| 1400 | 760 | 53.8 | 371 | 71.0 | 490 | 135.0 |
| 1600 | 871 | 29.6 | 204 | 34.7 | 239 | 160.6 |
| 1800 | 982 | 9.9 | 68 | 15.3 | 106 | 154.5 |
| 2000 | 1093 | 5.0 | 35 | 8.7 | 60 | 128.3 |
Hot-Rolled and 1925°F (1052°C) Mill-Annealed, Plate
| Test Temperature | 0.2% Yield Strength | Ultimate Tensile Strength | Elongation | |||
| °F | °C | ksi | MPa | ksi | MPa | % |
| RT | RT | 60.5 | 417 | 129.6 | 894 | 48 |
| 800* | 427* | 46.4 | 320 | 116.1 | 800 | 51.5 |
| 1000 | 538 | 44.8 | 309 | 112.3 | 774 | 52.1 |
| 1200 | 649 | 43.7 | 301 | 112.7 | 777 | 80.3 |
| 1400 | 760 | 43.7 | 301 | 71.1 | 490 | 102.2 |
| 1600 | 871 | 30.6 | 211 | 38.0 | 262 | 115.7 |
| 1800 | 982 | 11.8 | 81 | 17.3 | 119 | 120.7 |
| 2000 | 1093 | 5.4 | 37 | 9.3 | 64 | 135.1 |
*Average of results for only two products
RT=Room Temperature
Comparative Elevated Temperature Yield Strengths, Sheet
Creep and Rupture Properties
HAYNES 625 Sheet, Solution Annealed
Temperature
Creep
Approximate Initial Stress to Produce Specified Creep in
10 h
100 h
1,000 h
°F
°C
%
ksi
MPa
ksi
MPa
ksi
MPa
1100
593
0.5
75
517
69
476
64
441
1
76
524
71
490
67
462
R
-
-
90
621
80
552
1200
649
0.5
53
365
52
359
50
345
1
58
400
53
365
51
352
R
84
579
74
510
55
379
1300
704
0.5
33
228
30
207
26
179
1
36
248
31
214
27
186
R
68*
469*
49
338
33
228
1400
760
0.5
18.4
127
13.0
90
9.7
67
1
20
138
14.5
100
11.5
79
R
41
283
27
186
17.8
123
1500
816
0.5
9.7
67
5.7
39
3.2
22
1
11.3
78
7.0
48
4.2
29
R
24
165
15.2
105
9.9
68
1600
871
0.5
5.2
36
2.6
18
1.2
8.3
1
6.2
43
3.3
23
1.6
11
R
14.0
97
8.0
55
4.2
29
1700
927
0.5
2.6
18
1.1
7.6
-
-
1
3.4
23
1.7
12
-
-
R
8.0*
55*
4.3
30
2.7
19
1800
982
0.5
1.2
8.3
-
-
-
-
1
1.7
12
0.5
3.4
-
-
R
4.1
28
2.6
18
1.4
10
| Temperature | Creep | Approximate Initial Stress to Produce Specified Creep in | ||||||
| 10 h | 100 h | 1,000 h | ||||||
| °F | °C | % | ksi | MPa | ksi | MPa | ksi | MPa |
| 1100 | 593 | 0.5 | 75 | 517 | 69 | 476 | 64 | 441 |
| 1 | 76 | 524 | 71 | 490 | 67 | 462 | ||
| R | - | - | 90 | 621 | 80 | 552 | ||
| 1200 | 649 | 0.5 | 53 | 365 | 52 | 359 | 50 | 345 |
| 1 | 58 | 400 | 53 | 365 | 51 | 352 | ||
| R | 84 | 579 | 74 | 510 | 55 | 379 | ||
| 1300 | 704 | 0.5 | 33 | 228 | 30 | 207 | 26 | 179 |
| 1 | 36 | 248 | 31 | 214 | 27 | 186 | ||
| R | 68* | 469* | 49 | 338 | 33 | 228 | ||
| 1400 | 760 | 0.5 | 18.4 | 127 | 13.0 | 90 | 9.7 | 67 |
| 1 | 20 | 138 | 14.5 | 100 | 11.5 | 79 | ||
| R | 41 | 283 | 27 | 186 | 17.8 | 123 | ||
| 1500 | 816 | 0.5 | 9.7 | 67 | 5.7 | 39 | 3.2 | 22 |
| 1 | 11.3 | 78 | 7.0 | 48 | 4.2 | 29 | ||
| R | 24 | 165 | 15.2 | 105 | 9.9 | 68 | ||
| 1600 | 871 | 0.5 | 5.2 | 36 | 2.6 | 18 | 1.2 | 8.3 |
| 1 | 6.2 | 43 | 3.3 | 23 | 1.6 | 11 | ||
| R | 14.0 | 97 | 8.0 | 55 | 4.2 | 29 | ||
| 1700 | 927 | 0.5 | 2.6 | 18 | 1.1 | 7.6 | - | - |
| 1 | 3.4 | 23 | 1.7 | 12 | - | - | ||
| R | 8.0* | 55* | 4.3 | 30 | 2.7 | 19 | ||
| 1800 | 982 | 0.5 | 1.2 | 8.3 | - | - | - | - |
| 1 | 1.7 | 12 | 0.5 | 3.4 | - | - | ||
| R | 4.1 | 28 | 2.6 | 18 | 1.4 | 10 | ||
*Significant extrapolation
Comparison of Stress to Produce 1% Creep in 1,000 Hours
Thermal Stability
HAYNES® 625 alloy is similar to the solid-solution-strengthened superalloys, such as HAYNES® 188 alloy or HASTELLOY® X alloy, which will precipitate deleterious phases upon long- term exposure at intermediate temperatures. In this case, the phase in question is NiCb delta- phase which serves to impair both tensile ductility and impact strength. For applications where thermal stability is important, 230® alloy is recommended.
Room Temperature Properties After Thermal Exposure, Plate
| Exposure | h | 0.2% Offset Yield Strength | Ultimate Tensile Strength | Elongation | Impact | ||||
| °F | °C | h | ksi | MPa | ksi | MPa | % | ft.-lb. | J |
| As-annealed* | – | 66.2 | 456 | 127.7 | 880 | 46 | 81 | 110 | |
| 1200 | 649 | 1000 | 122.3 | 843 | 165.0 | 1138 | 28 | 11 | 15 |
| 4000 | 117.9 | 813 | 163.6 | 1128 | 24 | 8 | 11 | ||
| 8000 | 117.8 | 812 | 164.2 | 1132 | 18 | 5 | 7 | ||
| 16000 | 118.5 | 817 | 165.4 | 1140 | 12 | 4 | 5 | ||
| 1400 | 760 | 1000 | 95.5 | 658 | 142.9 | 985 | 17 | 5 | 7 |
| 4000 | 104.1 | 718 | 145.5 | 1003 | 12 | 4 | 5 | ||
| 8000 | 97.4 | 672 | 142.6 | 983 | 13 | 5 | 7 | ||
| 16000 | 96.1 | 663 | 140.4 | 968 | 12 | 4 | 5 | ||
| 1600 | 871 | 1000 | 68.3 | 471 | 130.0 | 896 | 30 | 12 | 16 |
| 4000 | 66.4 | 458 | 130.0 | 896 | 29 | 11 | 15 | ||
| 8000 | 63.7 | 439 | 127.0 | 876 | 26 | 15 | 20 | ||
| 16000 | 63.4 | 437 | 128.4 | 885 | 32 | 14 | 19 | ||
*1875°F (1024°C), rapid cooled
Oxidation Resistance
Comparative Burner Rig Oxidation Resistance, 1000 Hours
Burner rig oxidation tests were conducted by exposing samples 3/8 in. x 2.5 in. x thickness (9 mm x 64 mm x thickness), in a rotating holder, to products of combustion of a mixture of No. 1 and No. 2 fuel oil. This was burned at a ratio of air to fuel of about 50:1 for 1000 hours. (Gas velocity was about 0.3 mach). Samples were automatically removed from the gas stream every 30 minutes, fan-cooled to near ambient temperature, and then reinserted into the flame tunnel.
| Alloy | 1800°F (982°C) | |||||
| Metal Loss | Average Metal Affected | Maximum Metal Affected | ||||
| – | mils | µm | mils | µm | mils | µm |
| 230® | 0.8 | 20 | 2.8 | 71 | 3.5 | 89 |
| X | 2.7 | 69 | 5.6 | 142 | 6.4 | 153 |
| 625 | 4.9 | 124 | 7.1 | 180 | 7.6 | 193 |
| 25 | 6.2 | 157 | 8.3 | 211 | 8.7 | 221 |
| MULTIMET® | 11.8 | 300 | 14.4 | 366 | 14.8 | 376 |
| 800H® | 12.7 | 312 | 14.5 | 368 | 15.3 | 389 |
Oxidation Resistance in Flowing Air (1008 Hours)
The following are static oxidation test rankings for 1008-hour exposures in flowing air. The samples were cycled to room temperature weekly. Average metal affected is the sum of metal loss plus average internal penetration.
| Alloy | 1600°F (871°C) | 1800°F (982°C) | ||||||
| Metal Loss | Avg. Met. Aff. mils, (mm) | Metal Loss | Avg. Met. Aff. mils, (mm) | |||||
| – | mils | μm | mils | μm | mils | μm | mils | μm |
| 214® | 0 | 0 | 0.1 | 3 | 0.1 | 3 | 0.3 | 8 |
| 188 | – | – | – | – | 0.1 | 3 | 1.1 | 28 |
| 230® | 0 | 0 | 0.6 | 15 | 0.2 | 5 | 1.5 | 38 |
| X | 0.1 | 3 | 0.7 | 18 | 0.2 | 5 | 1.5 | 38 |
| 625 | 0.1 | 3 | 0.6 | 15 | 0.4 | 10 | 1.9 | 48 |
| 617 | – | – | – | – | 0.3 | 8 | 2.0 | 51 |
| 25 | – | – | – | – | 0.3 | 8 | 2.0 | 51 |
| HR‐120® | 0.1 | 3 | 0.9 | 23 | 0.4 | 10 | 2.1 | 53 |
| 556® | – | – | – | – | 0.4 | 10 | 2.3 | 58 |
| 800HT | 0.1 | 3 | 1.0 | 25 | 0.5 | 13 | 4.1 | 104 |
| HR‐160® | 0.2 | 5 | 3.0 | 79 | 0.7 | 18 | 5.5 | 140 |
(Cycled weekly); alloys are arranged in ascending order by the average metal affected.
Amount of metal affected for high‐temperature sheet (0.060 ‐0.125”) alloys exposed for 360 days (8,640‐h) in flowing air at 1600°F (871°C) (Cycled once‐a‐month)
| Alloy | Metal Loss | Avg. Met. Aff. | ||
| mils | μm | mils | μm | |
| 214® | 0.1 | 3 | 0.2 | 5 |
| 625 | 0.3 | 8 | 1.4 | 36 |
| 230® | 0.2 | 5 | 1.4 | 36 |
| 617 | 0.3 | 8 | 1.6 | 41 |
| HR‐120® | 0.3 | 8 | 1.6 | 41 |
| 25 | 0.3 | 8 | 1.7 | 43 |
| 188 | 0.2 | 5 | 1.8 | 46 |
| 556® | 0.3 | 8 | 1.9 | 48 |
| X | 0.3 | 8 | 2.2 | 56 |
| 800HT | 0.4 | 10 | 2.9 | 74 |
Comparative Dynamic Oxidation
| Alloy | 1600°F (871°C), 2000 h, 30-min cycles | 1800°F (982°C), 1000 h, 30-min cycles | ||||||
| Metal Loss | Average Metal Affected | Metal Loss | Average Metal Affected | |||||
| mils | µm | mils | µm | mils | µm | mils | µm | |
| 188 | 1.1 | 28 | 2.9 | 74 | 1.1 | 28 | 3.2 | 81 |
| 230® | 0.9 | 23 | 3.9 | 99 | 2.8 | 71 | 5.6 | 142 |
| 617 | 2.0 | 51 | 7.8 | 198 | 2.4 | 61 | 5.7 | 145 |
| 625 | 1.2 | 30 | 2.2 | 56 | 3.7 | 94 | 6.0 | 152 |
| 556® | 1.5 | 38 | 3.9 | 99 | 4.1 | 104 | 6.7 | 170 |
| X | 1.7 | 43 | 5.3 | 135 | 4.3 | 109 | 7.3 | 185 |
| HR-120® | – | – | – | – | 6.3 | 160 | 8.3 | 211 |
| RA330 | 2.5 | 64 | 5.0 | 127 | 8.7 | 221 | 10.5 | 267 |
| HR-160® | – | – | – | – | 5.4 | 137 | 11.9 | 302 |
| 310SS | 6.0 | 152 | 7.9 | 201 | 16.0 | 406 | 18.3 | 465 |
| 800H | 3.9 | 99 | 9.4 | 239 | 22.9 | 582 | Through Thickness | |
Amount of metal affected for high-temperature sheet alloys exposed for 1008h
(cycled weekly) in air + 10%H2O
| Alloy | 1600°F (871°C) | 1800°F (982°C) | ||||||
| Metal Loss | Avg. Met. Aff. | Metal Loss | Avg. Met. Aff. | |||||
| mils | μm | mils | μm | mils | μm | mils | μm | |
| 214® | 0.1 | 1 | 0.3 | 7 | 0.0 | 1 | 0.2 | 6 |
| 188 | – | – | – | – | 0.1 | 3 | 1.4 | 36 |
| 230® | 0.1 | 2 | 0.5 | 13 | 0.2 | 4 | 1.5 | 37 |
| 625 | 0.1 | 3 | 0.5 | 12 | 0.3 | 8 | 1.6 | 41 |
| X | 0.0 | 1 | 0.5 | 13 | 0.3 | 7 | 1.8 | 45 |
| HR-120® | 0.1 | 2 | 0.7 | 17 | 0.3 | 9 | 1.9 | 49 |
| 617 | 0.1 | 2 | 0.9 | 22 | 0.3 | 8 | 2.0 | 51 |
Metallographic Technique used for Evaluating Environmental Tests
Physical Properties
| Physical Property | British Units | Metric Units | ||
| Density | RT |
0.305lb/in3 |
RT |
8.44 g/cm3 |
| Melting Range | 2350-2460°F | – | 1288-1349°C | – |
| Electrical Resistivity | RT | 50.8 µohm-in | RT | 129 µohm-cm |
| 200°F | 52.0 µohm-in | 100°C | 132 µohm-cm | |
| 400°F | 52.8 µohm-in | 200°C | 134 µohm-cm | |
| 600°F | 53.1 µohm-in | 300°C | 135 µohm-cm | |
| 800°F | 53.5 µohm-in | 400°C | 136 µohm-cm | |
| 1000°F | 54.3 µohm-in | 500°C | 137 µohm-cm | |
| 1200°F | 54.3 µohm-in | 600°C | 138 µohm-cm | |
| 1400°F | 53.9 µohm-in | 700°C | 138 µohm-cm | |
| 1600°F | 53.5 µohm-in | 800°C | 137 µohm-cm | |
| 1800°F | 53.1 µohm-in | 900°C | 136 µohm-cm | |
| – | – | 1000°C | 135 µohm-cm | |
| Thermal Conductivity | RT |
68 Btu-in/ft2-hr-°F |
RT | 9.8 W/m-°C |
| 200°F |
75 Btu-in/ft2-hr-°F |
100°C | 10.9 W/m-°C | |
| 400°F |
87 Btu-in/ft2-hr-°F |
200°C | 12.5 W/m-°C | |
| 600°F |
98 Btu-in/ft2-hr-°F |
300°C | 13.9 W/m-°C | |
| 800°F |
109 Btu-in/ft2-hr-°F |
400°C | 15.3 W/m-°C | |
| 1000°F |
121 Btu-in/ft2-hr-°F |
500°C | 16.9 W/m-°C | |
| 1200°F |
132 Btu-in/ft2-hr-°F |
600°C | 18.3 W/m-°C | |
| 1400°F |
144 Btu-in/ft2-hr-°F |
700°C | 19.8 W/m-°C | |
| 1600°F |
158 Btu-in/ft2-hr-°F |
800°C | 21.5 W/m-°C | |
| 1800°F |
175 Btu-in/ft2-hr-°F |
900°C | 23.4 W/m-°C | |
| – | – | 1000°C | 25.6W/m-°C | |
| Specific Heat | RT | 0.098 Btu/lb.-°F | RT | 410 J/Kg-°C |
| 200°F | 0.102 Btu/lb.-°F | 100°C | 428 J/Kg-°C | |
| 400°F | 0.109 Btu/lb.-°F | 200°C | 455 J/Kg-°C | |
| 600°F | 0.115 Btu/lb.-°F | 300°C | 477 J/Kg-°C | |
| 800°F | 0.122 Btu/lb.-°F | 400°C | 503 J/Kg-°C | |
| 1000°F | 0.128 Btu/lb.-°F | 500°C | 527 J/Kg-°C | |
| 1200°F | 0.135 Btu/lb.-°F | 600°C | 552 J/Kg-°C | |
| 1400°F | 0.141 Btu/lb.-°F | 700°C | 576 J/Kg-°C | |
| 1600°F | 0.148 Btu/lb.-°F | 800°C | 600 J/Kg-°C | |
| 1800°F | 0.154 Btu/lb.-°F | 900°C | 625 J/Kg-°C | |
| - | - | 1000°C | 648 J/Kg-°C | |
| Mean Coefficient of Thermal Expansion | 70-200°F | 7.1 µin/in-°F | 25-100°C |
12.8 x 10-6 µm/m- °C |
| 70-400°F | 7.3 µin/in-°F | 25-200°C |
13.1 x 10-6 µm/m- °C |
|
| 70-600°F | 7.5 µin/in-°F | 25-300°C |
13.4 x 10-6 µm/m- °C |
|
| 70-800°F | 7.7 µin/in-°F | 25-400°C |
13.8 x 10-6 µm/m- °C |
|
| 70-1000°F | 8.0 µin/in-°F | 25-500°C |
14.2 x 10-6 µm/m- °C |
|
| 70-1200°F | 8.4 µin/in-°F | 25-600°C |
14.8 x 10-6 µm/m- °C |
|
| 70-1400°F | 8.7 µin/in-°F | 25-700°C |
15.4 x 10-6 µm/m- °C |
|
| 70-1600°F | 9.2 µin/in-°F | 25-800°C |
16.0 x 10-6 µm/m- °C |
|
| 70-1800°F | 9.6 µin/in-°F | 25-900°C |
16.7 x 10-6 µm/m- °C |
|
| - | - | 25-1000°C |
17.4 x 10-6 µm/m- °C |
|
| Dynamic Modulus of Elasticity | RT |
30.2 x 106 psi |
RT | 208 GPa |
| 200°F |
29.2 x 106 psi |
100°C | 201 GPa | |
| 400°F |
28.8 x 106 psi |
200°C | 199 GPa | |
| 600°F |
27.7 x 106 psi |
300°C | 192 GPa | |
| 800°F |
26.7 x 106 psi |
400°C | 186 GPa | |
| 1000°F |
25.6 x 106 psi |
500°C | 179 GPa | |
| 1200°F |
24.3 x 106 psi |
600°C | 171 GPa | |
| 1400°F |
22.8 x 106 psi |
700°C | 163 GPa | |
| 1600°F |
21.2 x 106 psi |
800°C | 153 GPa | |
| 1800°F |
18.7 x 106 psi |
900°C | 142 GPa | |
| - | - | 1000°C | 126 GPa | |
RT = Room Temperature
Iso-Corrosion Diagrams
Each of these iso-corrosion diagrams was constructed using numerous corrosion rate values, generated at different acid concentrations and temperatures. The blue line represents those combinations of acid concentration and temperature at which a corrosion rate of 0.1 mm/y (4 mils per year) is expected, based on laboratory tests in reagent grade acids. Below the line, rates under 0.1 mm/y are expected. Similarly, the red line indicates the combinations of acid concentration and temperature at which a corrosion rate of 0.5 mm/y (20 mils per year) is expected. Above the line, rates over 0.5 mm/y are expected. Between the blue and red lines, corrosion rates are expected to fall between 0.1 and 0.5 mm/y.
Hydrobromic Acid
| Concentration | 50°F | 75°F | 100°F | 125°F | 150°F | 175°F | 200°F | 225°F | Boiling |
| Wt. % | 10°C | 24°C | 38°C | 52°C | 66°C | 79°C | 93°C | 107°C | |
| 2.5 | – | – | – | – | <0.01 | – | <0.01 | – | <0.01 |
| 5 | – | – | – | – | <0.01 | 0.13 | 0.6 | – | – |
| 7.5 | – | – | – | – | <0.01 | <0.01 | 0.93 | – | – |
| 10 | – | – | – | – | 0.15 | 0.82 | – | – | – |
| 15 | – | – | <0.01 | 0.3 | 0.64 | – | – | – | – |
| 20 | – | 0.1 | 0.16 | 0.33 | 0.65 | – | – | – | – |
| 25 | – | – | – | – | – | – | – | – | – |
| 30 | – | – | 0.11 | 0.21 | 0.34 | 0.72 | – | – | – |
| 40 | – | – | 0.08 | 0.15 | 0.25 | 0.42 | 0.79 | – | – |
All corrosion rates are in millimeters per year (mm/y); to convert to mils (thousandths of an inch) per year, divide by 0.0254.
Data are from Corrosion Laboratory Job 17-04.
All tests were performed in reagent grade acids under laboratory conditions; field tests are encouraged prior to industrial use.
Hydrochloric Acid
| Concentration | 50°F | 75°F | 100°F | 125°F | 150°F | 175°F | 200°F | 225°F | Boiling |
| Wt. % | 10°C | 24°C | 38°C | 52°C | 66°C | 79°C | 93°C | 107°C | – |
| 1 | – | – | – | – | – | <0.01 | <0.01 | – | 0.23 |
| 1.5 | – | – | – | – | – | – | – | – | – |
| 2 | – | – | – | – | – | – | – | – | – |
| 2.5 | – | – | – | – | – | – | – | – | – |
| 3 | – | – | <0.01 | <0.01 | <0.01 | 2.07 | – | – | – |
| 3.5 | – | – | – | – | – | – | – | – | – |
| 4 | – | – | – | – | – | – | – | – | – |
| 4.5 | – | – | – | – | – | – | – | – | – |
| 5 | – | – | <0.01 | <0.01 | – | 4.65 | – | – | – |
| 7.5 | – | – | 0.07 | 0.49 | – | – | – | – | – |
| 10 | <0.01 | 0.15 | 0.3 | 1.16 | – | – | – | – | – |
| 15 | 0.06 | 0.19 | 0.4 | 1.06 | – | – | – | – | – |
| 20 | 0.06 | 0.16 | 0.36 | 0.82 | – | – | – | – | – |
All corrosion rates are in millimeters per year (mm/y); to convert to mils (thousandths of an inch) per year, divide by 0.0254.
Data are from Corrosion Laboratory Jobs 56-97 and 3-98.
All tests were performed in reagent grade acids under laboratory conditions; field tests are encouraged prior to industrial use.
Sulfuric Acid
| Concentration | 75°F | 100°F | 125°F | 150°F | 175°F | 200°F | 225°F | 250°F | 275°F | 300°F | 350°F | Boiling |
| Wt. % | 24°C | 38°C | 52°C | 66°C | 79°C | 93°C | 107°C | 121°C | 135°C | 149°C | 177°C | – |
| 1 | – | – | – | – | – | – | – | – | – | – | – | – |
| 2 | – | – | – | – | – | – | – | – | – | – | – | – |
| 3 | – | – | – | – | – | – | – | – | – | – | – | – |
| 4 | – | – | – | – | – | – | – | – | – | – | – | – |
| 5 | – | – | – | – | <0.01 | 0.06 | – | – | – | – | – | 0.4 |
| 10 | – | – | – | – | 0.01 | 0.24 | – | – | – | – | – | 1.05 |
| 20 | – | – | – | – | 0.02 | 0.58 | – | – | – | – | – | 2.84 |
| 30 | – | – | – | 0.01 | 0.03 | 0.68 | – | – | – | – | – | – |
| 40 | – | – | <0.01 | 0.02 | 0.58 | – | – | – | – | – | – | – |
| 50 | – | – | – | 0.01 | 0.89 | – | – | – | – | – | – | – |
| 60 | – | – | <0.01 | 0.48 | 0.92 | – | – | – | – | – | – | – |
| 70 | – | <0.01 | 0.23 | 0.63 | – | – | – | – | – | – | – | – |
| 80 | – | 0.05 | 0.31 | 0.91 | 2.54 | – | – | – | – | – | – | – |
| 90 | <0.01 | 0.17 | 1.26 | – | 6.97 | – | – | – | – | – | – | – |
| 96 | – | – | – | – | – | – | – | – | – | – | – | – |
All corrosion rates are in millimeters per year (mm/y); to convert to mils (thousandths of an inch) per year, divide by 0.0254.
Data are from Corrosion Laboratory Jobs 57-97 and 4-98.
All tests were performed in reagent grade acids under laboratory conditions; field tests are encouraged prior to industrial use.
Comparative 0.1 mm/y Line Plots
To compare the performance of HAYNES® 625 alloy with that of other materials, it is useful to plot the 0.1 mm/y lines. In the following graphs, the lines for 625 alloy are compared with those of G-35 alloy, 254SMO alloy, and 316L stainless steel, in hydrochloric and sulfuric acids. The hydrochloric acid concentration limit of 20% is the azeotrope, above which corrosion tests are less reliable.
Selected Corrosion Data
Hydrobromic Acid
| Conc.Wt.% | 50°F | 75°F | 100°F | 125°F | 150°F | 175°F | 200°F | 225°F | Boiling |
| 10°C | 24°C | 38°C | 52°C | 66°C | 79°C | 93°C | 107°C | – | – |
| 2.5 | – | – | – | – | <0.01 | – | <0.01 | – | <0.01 |
| 5 | – | – | – | – | <0.01 | 0.13 | 0.60 | – | – |
| 7.5 | – | – | – | – | <0.01 | <0.01 | 0.93 | – | – |
| 10 | – | – | – | – | 0.15 | 0.82 | – | – | – |
| 15 | – | – | <0.01 | 0.30 | 0.64 | – | – | – | – |
| 20 | – | 0.01 | 0.16 | 0.33 | 0.65 | – | – | – | – |
| 25 | – | – | – | – | – | – | – | – | – |
| 30 | – | – | 0.11 | 0.21 | 0.34 | 0.72 | – | – | – |
| 40 | – | – | 0.08 | 0.15 | 0.25 | 0.42 | 0.79 | – | – |
All corrosion rates are in millimeters per year (mm/y); to convert to mils (thousandths of an inch) per year, divide by 0.0254.
Data are from Corrosion Laboratory Job 17-04.
All tests were performed in reagent grade acids under laboratory conditions; field tests are encouraged prior to industrial use.
Hydrochloric Acid
| Conc.Wt.% | 50°F | 75°F | 100°F | 125°F | 150°F | 175°F | 200°F | 225°F | Boiling |
| 10°C | 24°C | 38°C | 52°C | 66°C | 79°C | 93°C | 107°C | – | – |
| 1 | – | – | – | – | – | <0.01 | <0.01 | – | 0.23 |
| 1.5 | – | – | – | – | – | – | – | – | – |
| 2 | – | – | – | – | – | – | – | – | – |
| 2.5 | – | – | – | – | – | – | – | – | – |
| 3 | – | – | <0.01 | <0.01 | <0.01 | 2.07 | – | – | – |
| 3.5 | – | – | – | – | – | – | – | – | – |
| 4 | – | – | – | – | – | – | – | – | – |
| 4.5 | – | – | – | – | – | – | – | – | – |
| 5 | – | – | <0.01 | <0.01 | – | 4.65 | – | – | – |
| 7.5 | – | – | 0.07 | 0.49 | – | – | – | – | – |
| 10 | <0.01 | 0.15 | 0.30 | 1.16 | – | – | – | – | – |
| 15 | 0.06 | 0.19 | 0.40 | 1.06 | – | – | – | – | – |
| 20 | 0.06 | 0.16 | 0.36 | 0.82 | – | – | – | – | – |
All corrosion rates are in millimeters per year (mm/y); to convert to mils (thousandths of an inch) per year, divide by 0.0254.
Data are from Corrosion Laboratory Jobs 56-97 and 3-98.
All tests were performed in reagent grade acids under laboratory conditions; field tests are encouraged prior to industrial use.
Sulfuric Acid
| Conc.Wt.% | 75°F | 100°F | 125°F | 150°F | 175°F | 200°F | 225°F | 250°F | 275°F | 300°F | 350°F | Boiling |
| 24°C | 38°C | 52°C | 66°C | 79°C | 93°C | 107°C | 121°C | 135°C | 149°C | 177°C | – | – |
| 1 | – | – | – | – | – | – | – | – | – | – | – | – |
| 2 | – | – | – | – | – | – | – | – | – | – | – | – |
| 3 | – | – | – | – | – | – | – | – | – | – | – | – |
| 4 | – | – | – | – | – | – | – | – | – | – | – | – |
| 5 | – | – | – | – | <0.01 | 0.06 | – | – | – | – | – | 0.40 |
| 10 | – | – | – | – | 0.01 | 0.24 | – | – | – | – | – | 1.05 |
| 20 | – | – | – | – | 0.02 | 0.58 | – | – | – | – | – | 2.84 |
| 30 | – | – | – | 0.01 | 0.03 | 0.68 | – | – | – | – | – | – |
| 40 | – | – | <0.01 | 0.02 | 0.58 | – | – | – | – | – | – | – |
| 50 | – | – | – | 0.01 | 0.89 | – | – | – | – | – | – | – |
| 60 | – | – | <0.01 | 0.48 | 0.92 | – | – | – | – | – | – | – |
| 70 | – | <0.01 | 0.23 | 0.63 | – | – | – | – | – | – | – | – |
| 80 | – | 0.05 | 0.31 | 0.91 | 2.54 | – | – | – | – | – | – | – |
| 90 | <0.01 | 0.17 | 1.26 | – | 6.97 | – | – | – | – | – | – | – |
| 96 | – | – | – | – | – | – | – | – | – | – | – | – |
All corrosion rates are in millimeters per year (mm/y); to convert to mils (thousandths of an inch) per year, divide by 0.0254.
Data are from Corrosion Laboratory Jobs 57-97 and 4-98.
All tests were performed in reagent grade acids under laboratory conditions; field tests are encouraged prior to industrial use.
Resistance to Pitting and Crevice Corrosion
HAYNES® 625 alloy exhibits good resistance to chloride-induced pitting and crevice attack, forms of corrosion to which some of the austenitic stainless steels are particularly prone. To assess the resistance of alloys to pitting and crevice attack, it is customary to measure their Critical Pitting Temperatures and Critical Crevice Temperatures in acidified 6 wt.% ferric chloride, in accordance with the procedures defined in ASTM Standard G 48. These values represent the lowest temperatures at which pitting and crevice attack are encountered in this solution, within 72 hours.
| Alloy | Critical Pitting Temperature | Critical Crevice Temperature | ||
|
in Acidified 6% FeCl3 |
in Acidified 6% FeCl3 |
|||
| °F | °C | °F | °C | |
| 316L | 59 | 15 | 32 | 0 |
| 254SMO | 140 | 60 | 86 | 30 |
| 28 | 113 | 45 | 64 | 17.5 |
| 31 | 163 | 72.5 | 109 | 42.5 |
| G-30® | 154 | 67.5 | 100 | 37.5 |
| G-35® | 203 | 95 | 113 | 45 |
| 625 | 212 | 100 | 104 | 40 |
Resistance to Stress Corrosion Cracking
One of the chief attributes of the nickel alloys is their resistance to chloride-induced stress corrosion cracking. A common solution for assessing the resistance of materials to this extremely destructive form of attack is boiling 45% magnesium chloride (ASTM Standard G 36), typically with stressed U-bend samples. As is evident from the following results, 625 alloy is much more resistant to this form of attack than the comparative, austenitic stainless steels. The tests were stopped after 1,008 hours (six weeks).
| Alloy | Time to Cracking |
| 316L | 2 h |
| 254SMO | 24 h |
| 28 | 36 h |
| 31 | 36 h |
| G-30® | 168 h |
| G-35® | No Cracking in 1,008 h |
| 625 | No Cracking in 1,008 h |
Fabrication
Heat Treatment
HAYNES® 625 alloy is normally final annealed at 1925°F (1052°C) for a time commensurate with section thickness. Annealing during fabrication can be performed at even lower temperatures, but a final subsequent anneal at 1925°F (1052°C) is usually required to produce optimum structure and properties. Please see Haynes International publication H-3159 for further information.
Effect of Cold Reduction Upon Room-Temperature Properties
| Cold Reduction | Subsequent Anneal Temperature | 0.2% Yield Strength | Ultimate Tensile Strength | Elongation | Hardness | ||
| % | – | ksi | MPa | ksi | MPa | % | HR C/BW |
| None | None | 70 | 483 | 133 | 917 | 46 | 97 HRBW |
| 10 | None | 113 | 779 | 151 | 1041 | 30 | 32 HRC |
| 20 | 140 | 965 | 169 | 1165 | 16 | 37 HRC | |
| 30 | 162 | 1117 | 191 | 1317 | 11 | 40 HRC | |
| 40 | 178 | 1227 | 209 | 1441 | 8 | 42 HRC | |
| 50 | 184 | 1268 | 223 | 1538 | 5 | 45 HRC | |
| 10 | 1850°F (1010°C) | 63 | 434 | 134 | 924 | 46 | – |
| 20 | 71 | 490 | 138 | 951 | 44 | – | |
| 30 | 78 | 538 | 141 | 972 | 44 | – | |
| 40 | 82 | 565 | 141 | 972 | 42 | – | |
| 50 | 82 | 565 | 141 | 972 | 42 | – | |
| 10 | 1950°F (1065°C) | 61 | 421 | 133 | 915 | 46 | – |
| 20 | 71 | 490 | 137 | 945 | 45 | – | |
| 30 | 77 | 531 | 140 | 965 | 44 | – | |
| 40 | 83 | 572 | 142 | 979 | 42 | – | |
| 50 | 82 | 565 | 141 | 972 | 42 | – | |
| 10 | 2050°F (1120°C) | 58 | 400 | 128 | 883 | 50 | – |
| 20 | 67 | 462 | 135 | 931 | 46 | – | |
| 30 | 58 | 400 | 127 | 876 | 52 | – | |
| 40 | 72 | 496 | 137 | 945 | 44 | – | |
| 50 | 61 | 421 | 130 | 896 | 50 | – | |
| 10 | 2150°F (1175°C) | 52 | 359 | 122 | 841 | 55 | – |
| 20 | 54 | 372 | 124 | 855 | 55 | – | |
| 30 | 53 | 365 | 122 | 841 | 56 | – | |
| 40 | 52 | 359 | 122 | 841 | 55 | – | |
| 50 | 51 | 352 | 119 | 820 | 58 | – | |
*Tensile results are averages of two or more tests.
*Rapid Air Cool
HRC = Hardness Rockwell “C”.
HRBW = Hardness Rockwell “B”, Tungsten Indentor.
Welding
HAYNES® 625 alloy is readily welded by Gas Tungsten Arc (GTAW), Gas Metal Arc (GMAW), electron beam welding, and resistance welding techniques. Its welding characteristics are similar to those for HASTELLOY® X alloy. Submerged-Arc welding is not recommended as this process is characterized by high heat input to the base metal and slow cooling of the weld. These factors can increase weld restraint and promote cracking.
Base Metal Preparation
The welding surface and adjacent regions should be thoroughly cleaned with an appropriate solvent prior to any welding operation. All greases, oils, cutting oils, crayon marks, machining solutions, corrosion products, paint, scale, dye penetrant solutions, and other foreign matter should be completely removed. It is preferable, but not necessary, that the alloy be in the solution- annealed condition when welded.
Filler Metal Selection
Matching composition filler metal is recommended for joining 625 alloy. For dissimilar metal joining of 625 alloy to nickel-, cobalt-, or iron-base materials, 625 alloy itself, 230-W™ filler wire, 556™ alloy, HASTELLOY® S alloy (AMS5838), or HASTELLOY® W alloy (AMS 5786, 5787) welding products are suggested, depending upon the particular case. Please click here or see the Haynes Welding SmartGuide for more information.
Preheating, Interpass Temperatures, and Postweld Heat Treatment
Preheat is not required. Preheat is generally specified as room temperature (typical shop conditions). Interpass temperature should be maintained below 200°F (93°C). Auxiliary cooling methods may be used between weld passes, as needed, providing that such methods do not introduce contaminants. Postweld heat treatment is not generally required for X alloy. For further information, please click here.
Nominal Welding Parameters
Details for GTAW, GMAW and SMAW welding are given here. Nominal welding parameters are provided as a guide for performing typical operations and are based upon welding conditions used in our laboratories.
Specifications and Codes
Specifications
| HAYNES® 625 alloy (N06625, W86112) | |
| Sheet, Plate & Strip | AMS 5599SB 443/B 443AMS 5869P= 43 |
| Billet, Rod & Bar | AMS 5666SB 446/B 446B 472P= 43 |
| Coated Electrodes | SFA 5.11/ A 5.11(ENiCrMo-3)F= 43 |
| Bare Welding Rods & Wire | SFA 5.14/ A 5.14(ERNiCrMo-3)AMS 5837F=43 |
| Seamless Pipe & Tube | AMS 5581SB 444/B 444P= 43 |
| Welded Pipe & Tube | AMS 5581SB 704/B 704SB 705/B 705P= 43 |
| Fittings | SB 366/B 366P= 43 |
| Forgings | AMS 5666SB 564/B 564P= 43 |
| DIN | 17744 No. 2.4856NiCr22Mo9Nb |
| Others | ASME Code Case No. 2468NACE MR0175ISO 15156 |
Codes
| HAYNES® 625 alloy (N06625, W86112) | |||
| ASME | Section l |
Grade 1 1100ºF (593ºC)1 Code Case 2632 1200ºF (650ºC)2 Grade 2 1100ºF (593ºC)3 Code Case 1935 1000ºF (538ºC)3 |
|
| Section lll | Class 1 |
Grade 1800ºF (427ºC)3 |
|
| Class 2 |
Grade 1800ºF (427ºC)4 |
||
| Class 3 |
Grade 1800ºF (427ºC)4 |
||
| Section lV | HF-300.2 | – | |
| Section Vlll | Div. 1 |
Grade 11200ºF (649ºC)1Grade 21600ºF (871ºC)31200ºF (649ºC)5 |
|
| Div. 2 |
Grade 1800ºF (427ºC)5Code Case 2468800ºF (427ºC)6 |
||
| B16.5 |
1200°F (649°C)8 |
||
| B16.34 |
1200°F (649°C)6 |
||
| B31.1 |
1200°F (649°C)1 |
||
| B31.3 |
1200°F (649°C)6 |
||
| MMPDS | 6.3.3 | ||
1Plate, Sheet, Bar, Forgings, fittings, welded pipe/tube, seamless pipe/tube
2Plate, Sheet, welded pipe/tube
3Plate, Sheet, Bar, seamless pipe/tube
4Plate, Sheet, Bar, Forgings, welded pipe/tube, seamless pipe/tube
5Bolting
6Plate, Sheet, Bar, Forgings, seamless pipe/tube
7Plate, Sheet, Bar, seamless pipe/tube, Bolting
8Plate, Forgings
Disclaimer
Haynes International makes all reasonable efforts to ensure the accuracy and correctness of the data displayed on this site but makes no representations or warranties as to the data’s accuracy, correctness or reliability. All data are for general information only and not for providing design advice. Alloy properties disclosed here are based on work conducted principally by Haynes International, Inc. and occasionally supplemented by information from the open literature and, as such, are indicative only of the results of such tests and should not be considered guaranteed maximums or minimums. It is the responsibility of the user to test specific alloys under actual service conditions to determine their suitability for a particular purpose.
For specific concentrations of elements present in a particular product and a discussion of the potential health affects thereof, refer to the Safety Data Sheets supplied by Haynes International, Inc. All trademarks are owned by Haynes International, Inc., unless otherwise indicated.