Alloy 625 Tubing
Alloy 625 Tubing
Alloy 625 is an austenitic nickel-chromium-molybdenum superalloy known for being resistant to crevice corrosion and oxidation at elevated temperatures. These temperatures can range from cryogenic to extremely hot levels of 1,800°F. The behavior and chemical composition of this grade make it well suited for nuclear and aerospace applications. Also, with the addition of niobium, alloy 625 tubing finds itself with increased strength sans heat treating. This property makes the grade an excellent option for fabrication.
Product Specifications
ASTM B444 / ASME SB444 / NACE MR0175
Size Range
Outside Diameter (OD) | Wall Thickness |
.375"–.750" | .035”–.095” |
Chemical Requirements
Alloy 625 (UNS N06625)
Composition %
C | Mn | Si | P Phosphorous | Cr Chromium | Nb+Ta | Co | Mo | Fe | Al | Ti | Ni Nickel |
0.10 max | 0.50 max | 0.50 max | 0.015 max | 20.0–23.0 | 3.15–4.15 | 1.0 max | 8.0–10.0 | 5.0 max | 0.40 max | 0.40 max | 58.0 min |
Chemical Requirements
Alloy 625 (UNS N06625)
Composition %
C | Mn | Si | P | Cr | Nb+Ta | Co | Mo | Fe | Al | Ti | Ni |
0.10 max | 0.50 max | 0.50 max | 0.015 max | 20.0–23.0 | 3.15–4.15 | 1.0 max | 8.0–10.0 | 5.0 max | 0.40 max | 0.40 max | 58.0 min |
Dimensional Tolerances
OD | OD Tolerance | Wall Tolerance |
.375”–0.500” excl | +.004”/-.000” | ± 10% |
0.500”–1.250” excl | +.005”/-.000” | ± 10% |
Mechanical Properties
Yield Strength: | 60 ksi min |
Tensile Strength: | 120 ksi min |
Elongation (min 2"): | 30% |
Fabrication
Alloy 625 has excellent forming and welding characteristics, but is prone to work hardening.
Industry Applications
Aerospace
Alloy 625’s durability and resistance to extremely high temperatures makes it the preferred alloy for the tubing used in aerospace applications, specifically for exhaust systems.
Chemical Process
With exceptional fatigue resistance, alloy 625 is used in chemical processing equipment that handles mixed acids—oxidized and reduced acids.
Fabrication
Due to its excellent forming and welding characteristics, alloy 625 is commonly used in fabrication industry applications such as hydraulic systems.
Marine
Alloy 625 tubing is used in transducer controls, propulsion systems, and exhaust ducts for utility boats because of the material’s high resistance to potable and salt water environments and extraordinary level of corrosion resistance.
Oil & Gas
As a high-performance material, alloy 625 is used in seawater heat exchangers, power plants and offshore topside services in part due to its strength, high toughness, and weldability. See oil and gas for more information.
Power Generation
Alloy 625’s ability to resist pitting in high-temperature makes it an ideal candidate for specific nuclear applications, which include reactor core and control rod components in nuclear water reactors. See power generation for more information.