General Properties
Alloy 625 is an austenitic nickel-chromium-molybdenum-niobium alloy possessing a rare combination of outstanding corrosion resistance coupled with high strength from cryogenic temperatures to 1800°F (982°C).
The strength of Alloy 625 is derived from the solid-solution hardening of the nickel-chromium matrix by the presence of molybdenum and niobium. Therefore, precipitation-hardening treatments are not required.
The chemical composition of Alloy 625 is also responsible for its outstanding corrosion resistance in a variety of severe operating environments along with resistance to oxidation and carburization in high temperature service. The alloy is resistant to pitting, crevice corrosion, impingement corrosion, intergranular attack and is almost immune to chloride stress corrosion cracking.
Chemical Analysis
Weight % (all values are maximum unless a range is otherwise indicated)
| Nickel | 58.0 min. | Silicon | 0.50 |
| Chromium | 20.0 min.-23.0 max. | Phosphorus | 0.015 |
| Molybdenum | 8.0 min.-10.0 max. | Sulfur | 0.015 |
| Iron | 5.0 | Aluminum | 0.40 |
| Niobium (plus Tantalum) | 3.15 min.-4.15 max. | Titanium | 0.40 |
| Carbon | 0.10 | Cobalt (if determined) | 1.0 |
| Manganese | 0.50 |
Physical Properties
Density
0.305 lbs/in3
8.44 g/cm3
Specific Heat
0.102 BTU/lb-°F (32-212°F)
427 J/kg-°K (0-100°C)
Modulus of Elasticity
30.1 x 106 psi
207.5 GPa
Thermal Conductivity 200°F (100°C)
75 BTU/hr/ft2/ft/°F
10.8 W/m-°K
Melting Range
2350 – 2460°F
1290 – 1350°C
Electrical Resistivity
50.8 Microhm-in at 70°C
128.9 Microhm-cm at 210°C
Mean Coefficient of Thermal Expansion
| Temperature Range | |||
|---|---|---|---|
| °F | °C | in/in/°F | cm/cm°C |
| 200 | 93 | 7.1 x 10-6 | 12.8 x 10-6 |
| 400 | 204 | 7.3 x 10-6 | 13.1 x 10-6 |
| 600 | 316 | 7.4 x 10-6 | 13.3 x 10-6 |
| 800 | 427 | 7.6 x 10-6 | 13.7 x 10-6 |
| 1000 | 538 | 7.8 x 10-6 | 14.0 x 10-6 |
| 1200 | 649 | 8.2 x 10-6 | 14.8 x 10-6 |
| 1400 | 760 | 8.5 x 10-6 | 15.3 x 10-6 |
| 1600 | 871 | 8.8 x 10-6 | 15.8 x 10-6 |
| 1700 | 927 | 9.0 x 10-6 | 16.2 x 10-6 |
Mechanical Properties
Typicals Values at 68°F (20°C)
| Yield Strength 0.2% Offset | Ultimate Tensile Strength | Elongation in 2 in. | Hardness | ||
|---|---|---|---|---|---|
| psi (min.) | (MPa) | psi (min.) | (MPa) | % (min.) | (max.) |
| 65,000 | 448 | 125,000 | 862 | 50 | 200 Brinell |
