Alloy 625
Alloy 625 is a nickel-chromium-molybdenum alloy. Its outstanding strength and toughness in the temperature range cryogenic to 2000°F (1093°C) , which are derived primarily from the solid solution effects of niobium and molybdenum in it's nickel-chromium matrix. The alloy has excellent fatigue strength and stress-corrosion cracking resistance to chloride ions. Typical applications for Inconel 625 are heat shields, furnace hardware, gas turbine engine ducting, combustion liners and spray bars, chemical plant hardware, and special seawater applications.
Quken offers alloy 625 in following forms :
| Product form | Standard | Size available mm |
|---|---|---|
| Strip | ASTM B168 / ASME SB443 | 0.05~2.0*3~540*C |
| Sheet | ASME SB443 | 1.2~6*1000~1500*1000~6000 |
| Plate | ASME SB443 | 8~25*1000~2000*2000~6000 |
| Flanges | / | Custom |
| Seamless pipe/tube | ASME SB444 | φ5~219*0.5~8.18*9000 Max |
| Welded pipe/tube | ASME SB705 | φ40~630*2~16*13000 Max |
| Bar | ASME SB446 | φ3.5~200*100~6000 |
| Wire | ASME SB446 | φ1~3*C |
| Pipe fittings | / | Custom |
| Forgings | / | Custom |
Designations and standards:
| Standard | Material designation |
|---|---|
| EN | 2.4856 - NiCr22Mo9Nb |
| ISO | NC22DNb |
| UNS | N06625 |
Chemical composition %:
| Ni | Cr | Fe | Mo | Nb+Ta | Co | |
|---|---|---|---|---|---|---|
| MIN. | 58 | 20.0 | 8.0 | 3.15 | ||
| MAX. | 30.0 | 5.0 | 10.0 | 4.15 | 1.0 | |
| Mn | S | Si | C | Ti | Al | |
| MAX. | 0.5 | 0.015 | 0.5 | 0.4 | 0.4 | 0.1 |
HEAT TREATMENT
Annealing at 1,600-1,900° F (927 - 1,038° C) is done where high hardness, tensile and fatigue strength are desired. A solutionanneal at 2,000-2,200° F (1,093 - 1,204° C) is used where optimum creep-rupture strength is desired. Lower carbon versions of the alloy can be precipitation strengthened by aging up to 120 hours at temperatures from 1,050° F to1,350° F (566 - 732° C).
CORROSION RESISTANCE
The alloy shows good corrosion resistance in a wide variety of environments including most salt solutions and to chloride ion stresscorrosion cracking. The high molybdenum content makes the alloys resistant to pitting and crevice corrosion.
In the solution annealed variant Alloy 625 is highly resistant to many corrosive gas atmospheres:
- Good resistance to carburizing and scaling under static and cyclic conditions
- Resistance to nitriding
- Good resistance to gases containing halogens, and hydrogen chloride
| Material | Material No. | CPT | CCP | PREN 1) |
|---|---|---|---|---|
| 316 Ti | 1.4571 | 15 | ＜0 | 24 |
| 904 L | 1.4539 | 45 | 25 | 37 |
| N08926 | 1.4529 | 70 | 40 | 47 |
| Alloy 625 | 2.4856 | 75 | 55 | 51 |
| 1) PREN: pitting resistance equivalent number; PRE = 1 (% Cr) + 3,3 (% Mo) + 20 (% N) | ||||
Critical pitting temperature (CPT) and critical crevice temperature (CCT) of Alloy 625 in comparison to high alloyed stainless steels in 10 % FeCl3, x 6 H2O.
Physical Constants:
| Density | 0.305 lb/in3, 8.44g/cm3 |
| Melting Range (Approx.) | 2354-2462 °F / 1290-1350 °C |
| Electrical Resistivity | 129 Microhm·cm |
| Thermal Expansion Coefficient (25°C to 100°C) | 12.8 x 10-6/°C |
| Thermal Conductivity (100°C) | 9.8W/m·K |
Mechanical Properties:
| Yield Strength 0.2% Offset | Tensile Strength | Elongation In 2inches | Hardness | ||
|---|---|---|---|---|---|
| KSI | MPa | KSI | MPa | % | HRB |
| 50 Min | 345 Min | 110 Min | 760 Min | 35 Min | 220 Max |
Applications
- Bellows, expansion joints
- Motorsport exhaust and clamps
- Aircraft ducting and exhaust systems
- Turbine shroud rings
- Engine thrust-reverser systems
- Gaskets and damper seals
- Weld overlay and spacers for heat recovery systems
- Valve seats and components
- pipe in oil and gas industry