Printable PDF: Inconel® 625 Alloy
Inconel® 625 is a Nickel-Chromium-Molybdenum-Columbium (Niobium) alloy with excellent oxidation resistance, corrosion resistance, and strength at high temperatures. Age-hardening treatments are not required to obtain the high strength properties of Alloy 625 due to the solid solution effects of molybdenum and columbium on the nickel-chromium matrix.
I625 is resistant to chloride-ion stress-corrosion cracking, pitting, and stress-corrosion cracking making it suitable for seawater applications. Inconel® 625 can operate from cryogenic temperatures to 700°F (370°C).
Applications include: honeycomb, springs, seals, bellows, diaphragms, land-based turbine components, aircraft exhaust ducting, and heat exchangers.
Industries supplied include: Automotive, Marine, Chemical Processing, Power Generation, Nuclear, and Aerospace.
|Cr:||20.00 – 23.00|
|Mo:||8.00 – 10.00|
|Nb:||3.15 – 4.15|
At 70°F (At 20°C)
0.305 lb./in3 / (8.44 g/cm3)
Modulus of Elasticity (E)
30.1 x 103 ksi / (208 GPa)
Modulus of Rigidity (G)
11.8 x 103 ksi / (81.2 GPa)
Coefficient of Expansion
7.4 microinches/in.-°F (70-600°F) / (13.3 μm/m-°C) (20-538°C)
50.8 μ ohm.in / (129 μ ohm.cm)
68 Btu-in./ft.2hr.-°F / (9.8 W/m-K)
Strip and Foil – ASTM B443, AMS 5599, AMS 5869, ISO 6208, EN10095
Typical Mechanical Properties
120 – 150 ksi (830 – 1100 MPa)
Suggested Operating Conditions
-300°F to 700°F (-184°C to 370°C)
Spring Temper (Min)
200 – 250 ksi (1380 – 1724 MPa)
Suggested Operating Conditions
-300°F to 700°F (-184°C to 370°C)
Inconel® is a registered trademark of the Special Metals Corporation group of companies.
More Information for Inconel® 625 Nickel Alloy
Using metal over plastic has certain distinct advantages, including better tensile strength, durability, and useful life. We also know that metal alloys have a melting point higher than most plastics. That said, even these metal alloys tend to degrade when exposed to high heat.
How does steel measure up under high heat? There are many varieties of steel, and one the best for exposure to extremely high temperatures is an alloy known as Inconel 625.
What follows is a look at how Inconel 625 Nickel Alloy stands up against steel and stainless steel.
Plain Steel Alloys
A wide variety of alloys, which include mild-, low-, and high carbon steel, can be called plain steel. The one variable in all of these alloys which mostly affect the tensile strength and tempering of the steel is Carbon content. This means that plain steel can be heat treated to a degree that alters its mechanical properties, including yield strength and ductility. Plain steel can be heat treated to a maximum temperature of 1,292°F (700°C).
An interesting aspect to note is that as Carbon content increases in a plain steel alloy, the tolerance for higher temperatures tends to decrease. Plain steels are unsuited to environments where temperatures are consistently 2,000°F or higher.
Stainless Steel Alloys
As with plain steel, stainless steel can refer to a wide variety of alloys. Stainless steel has a protective oxide layer, which is its most outstanding feature.
Even though there are hundreds of different stainless steel alloys, there are commonly-used ones:
- Grade 304 Stainless Steel. This alloy can be heated to temperatures of 1,697°F (952°C). Significant loss of strength and corrosion resistance takes place at temperatures of about 2,000°F.
- Grade 316 Stainless Steel. This grade is more resistant to chemical corrosion at room temperature, but is less resistant to higher temperatures, at 2,000°F.
- Grade 330 Stainless Steel. Scaling and oxidation at high temperatures are a big problem and this stainless steel alloy has been specifically formulated for that exact purpose. Grade 330 SS has a high nickel and chromium content that allows it to withstand exposure to temperatures of 1,900°F (1037°) for long periods of time.
Some may recommend Grade 330 SS at temps of 2,000°F, but there is a better solution.
Inconel 625 Alloy
Inconel 625 is a specially-formulated family of alloys designed for use in environments where there are extremely high temperatures. At 2,000°F, Inconel 625 has a tensile strength of 13.3 KSI (13,300 psi). Room temperature strength of 625 Inconel is much less, at 138.8 KSI (138,800 psi), but this is still well over what it needs to retain its shape.
It is easy to see why Inconel 625 nickel alloy is the first choice of many. 625 Inconel is used because of its high strength and outstanding corrosion resistance. The extraordinary strength of the Inconel 625 comes from the stiffening effects of Molybdenum and Niobium on its Nickel-Chromium matrix. As a result of this, the need for precipitation hardening treatments is eliminated.
An alloy must have a particular chemical composition to be considered alloy 625:
- Ni 58% min
- Cr 20-23%
- Fe 5% max
- Mo 8-10%
- Nb 3.15-4.15%
- Co 1% max
- Si .50 max
- P and S .15% max
The unique composition of Inconel 625 nickel alloy makes it the only choice for environments where high temperature and severely corrosive conditions need superior resistance. For this reason, Alloy 625 is the perfect choice for applications in seawater, chemical processing, and aerospace.
Excellent Corrosion Resistance of Inconel 625 Alloy:
- Highly resistant to pitting and crevice corrosion in chloride-bearing environments as well as to impingement corrosion or inter-granular attack.
- Mineral acids like nitric phosphoric, sulphuric, and hydrochloric acids are highly resisted and corrosive attack prevented; alkalis and organic acid corrosion are also resisted.
Other Inconel 625 Properties:
- Excellent oxidation resistance
- High rupture, creep and tensile strength
- Excellent weld-ability and brazeability
- Best fatigue and thermal-fatigue strength
- Immune to chloride ion stress corrosion cracking
Inconel 625 Nickel Alloy is very versatile and is used in a variety of industries and applications, such as:
- Nuclear power production
- Marine/boating/undersea (bellows for submerged controls, electrical cable connectors, springs and seals)
- Nuclear reactor-cores and control-rod components
- Wire rope for cable and blades on naval craft such as gunboats and subs
- Oceanographic equipment
- Rings and tubing for environmental control systems
- Plant equipment in chemical processing field
- Flare stacks
- Meets ASME code for boiler and pressure vessels
Combined Metals of Chicago (CMC) offers Inconel 625 in pipe, tube, sheet, strip, plate, round bar, flat bar, forging stock, hexagon, wire, and extruded section.
When you are looking for a stainless steel with excellent oxidation resistance, corrosion resistance and high strength at high temperatures, your first choice should be Inconel 625. We will deliver your high-quality alloy to your exact specifications.
For high-quality products, customized to your specifications, with high-quality service, get in touch with one of our professionals today by calling 800-323-0758 or by visiting our Contact Us page.