Corrosion resistant alloys
| UNS Number | UNS N06625 |
| Industry Name | Alloy 625, Inconel 625, W.Nr.2.4819 |
| Product Forms | Billets, Bars, Forgings, Plates, Strips, Powders |
General Characteristics
Alloy 625 is a nickel-chromium-molybdenum-niobium superalloy designed for outstanding combination of high tensile strength, creep resistance and corrosion resistance without relying on precipitation hardening heat treatment.
It exhibits resistance to pitting, crevice corrosion and stress corrosion cracking in chloride-containing brines, seawater and acidic media, and maintains stable mechanical properties under cyclic thermal load up to around 980°C.
The alloy retains high ductility after welding and resists intergranular corrosion in the as-welded condition, suitable for fabrication of complex assemblies.
It delivers toughness and ductility at cryogenic temperatures, with no brittle transition even down to cryogenic ranges, making it well suited for cryogenic storage and low-temperature processing equipment.
As gas-atomized powder for additive manufacturing, Alloy 625 provides uniform microstructure and reliable high-temperature performance for aerospace, offshore and chemical processing custom components.
Alloy 625 chemical compositions
Ni | Fe | Mn | C | Si | S | Cr | Al | Ti | Nb+Ta | Mo | P | Co | |
Min | 58 | 20 | 3.15 | 8 | if determined | ||||||||
Max | 5 | 0.5 | 0.1 | 0.5 | 0.015 | 23 | 0.4 | 0.4 | 4.15 | 10 | 0.015 | 1 |
Technical Standards | Product Form |
ASTM B574 | Bar |
AMS 5650 | Bar |
ASTM B564 | Bar, Forging |
AMS 5536 | Plate, Sheet, Strip |
ASTM B575 | Plate, Sheet, Strip |
ASTM B619 | Welded pipe |
ASTM B618 | Welded tube |
ASTM B622 | Seamless pipe |
ASTM B574 | Wire |
AMS 5837 | Wire |
ASTM F3056 | Additive Manufacturing Powder |
AMS 7929 | Additive Manufacturing Powder |
Product form | Size range (mm) |
Forged bar | Dia.70-500 |
Rolled bar | Dia.2.0-70 |
Flat bar | T4-50*W60-300 |
Wire | Dia.0.25-18.0 |
Forged ring | OD 30-350* ID 30-350 |
Strip | 0.15-3.0 * 20-200 |
Plate | 1-25 * ≤1200 * ≤1200 |
Seamless tube | OD 6.0-200 * 0.6-20 |
1. Alloy 625 coefficient of thermal expansion
Physical Property | °C | Metric Units | °F | British Units |
Mean Coefficient of Thermal Expansion | 20-204 | 13.1x10(-6)m/m-°C | 68-400 | 7.3 micrinches/in.-°F |
20-316 | 13.5 | 68-600 | 7.5 | |
20-427 | 13.9 | 68-800 | 7.7 | |
20-538 | 14.4 | 68-1000 | 8 | |
20-649 | 15.1 | 68-1200 | 8.4 | |
20-760 | 15.7 | 68-1400 | 8.7 | |
20-871 | 16.6 | 68-1600 | 9.2 | |
20-982 | 17.3 | 68-1800 | 9.6 |
2. Alloy 625 oxidation resistance
Cyclic Oxidation/h | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | |
Weight Change/% | 980°C | 0.086 | 0.065 | 0.065 | 0.048 | 0.021 | / | 0.03 | -0.081 |
1095°C | -0.182 | -1.086 | -3.335 | -5.399 | -6.566 | -10.066 | / | / |
3. Alloy 625 SCC ( Stress Corrosion Cracking )
Test conditions and results of Inconel 625 specimens in air and high temperature steam
Test step | Temperature / °C | Medium environment | Loading method | CGR / mms-1 | Duration / h |
S1 | 700 | Air | Constant K | 3.39×10-8 | 146 |
S2 | 700 | Water vapor | Constant K | 5.43×10-8 | 161 |
S3 | 750 | Air | Constant K | 4.66×10-7 | 145 |
S4 | 750 | Water vapor | Constant K | 5.06×10-7 | 148 |
S5 | 725 | Air | Constant K | 1.48×10-7 | 156 |
S6 | 725 | Water vapor | Constant K | 2.08×10-7 | 172 |
4. Alloy 625 | Inconel 625 Embrittlement
It shows a pronounced susceptibility to hydrogen embrittlement at room temperature.
5. Alloy 625 modulus of elasticity
θ/°C | 20 | 95 | 205 | 315 | 425 | 540 | 650 | 760 | 870 |
E/GPa | 205 | 200 | 195 | 190 | 185 | 175 | 170 | 160 | 146 |