Inconel Alloys
UNS N06600 / N06625 / N07718 · For heat, corrosion and pressure together
Inconel is a family of nickel-chromium alloys used where stainless steel fails: high temperature oxidation, aggressive acids, and combinations of heat, pressure and corrosion. The nickel base makes them essentially immune to chloride stress corrosion cracking. We supply Inconel in pipe, tube, bar, fittings, flanges and fasteners.
When to specify Inconel
Choose Inconel when service temperature exceeds the practical limit of austenitic stainless, when chloride stress corrosion cracking must be eliminated, or when the medium is aggressive enough to attack 316 and duplex. 625 is the general corrosion-resistant choice, 600 the high-temperature oxidation choice, 718 the high-strength precipitation-hardened choice.
Chemical Composition (%)
Composition and mechanical values are the limits set by the governing ASTM specification and are given for reference. The mill test certificate supplied with your consignment carries the actual heat analysis.
| Element | Inconel 600 | Inconel 625 | Inconel 718 |
|---|---|---|---|
| Nickel | 72.0 min | 58.0 min | 50.0 – 55.0 |
| Chromium | 14.0 – 17.0 | 20.0 – 23.0 | 17.0 – 21.0 |
| Iron | 6.0 – 10.0 | 5.0 max | Balance |
| Molybdenum | — | 8.0 – 10.0 | 2.80 – 3.30 |
| Niobium + Tantalum | — | 3.15 – 4.15 | 4.75 – 5.50 |
| Titanium | — | 0.40 max | 0.65 – 1.15 |
| Aluminium | — | 0.40 max | 0.20 – 0.80 |
| Carbon | 0.15 max | 0.10 max | 0.08 max |
Mechanical & Physical Properties
| Property | Inconel 600 | Inconel 625 | Inconel 718 (aged) |
|---|---|---|---|
| Tensile strength | 550 MPa min | 827 MPa min | 1275 MPa min |
| Yield strength (0.2%) | 240 MPa min | 414 MPa min | 1034 MPa min |
| Elongation | 30% min | 30% min | 12% min |
| Density | 8.47 g/cm³ | 8.44 g/cm³ | 8.19 g/cm³ |
| Max continuous service | ≈ 1100 °C | ≈ 980 °C | ≈ 700 °C |
Governing Standards
| Standard | Covers |
|---|---|
| ASTM B167 / B517 | Alloy 600 pipe and tube |
| ASTM B444 / B704 | Alloy 625 pipe and tube |
| ASTM B166 / B446 | Bar and rod |
| ASTM B168 / B443 | Plate, sheet and strip |
| ASTM B366 | Buttweld fittings |
| ASTM B564 | Forged fittings and flanges |
Equivalent Designations
| Standard | Designation |
|---|---|
| UNS | N06600 / N06625 / N07718 |
| EN | 2.4816 / 2.4856 / 2.4668 |
| Werkstoff | NiCr15Fe / NiCr22Mo9Nb / NiCr19Fe19Nb5Mo3 |
Typical Applications
- Furnace and heat treatment components
- Offshore and subsea flowlines and tubing
- Chemical reactors and acid handling
- Gas turbine and aerospace hot sections
- Flare tips, burners and combustion hardware
Industries Served
- Oil & Gas
- Petrochemical
- Power
- Aerospace
- Chemical
Inconel Products We Supply
Available in the forms below, minimum order quantity 5 kg, with a mill test certificate to EN 10204 3.1 traceable to the heat number.
Need Inconel in a form not listed above? We source to requirement — and we will confirm availability and lead time.
Inconel by product form
Governing standards, dimensions and stock availability for each form.
Inconel — Frequently Asked Questions
- Which Inconel grade should I specify?
- 625 is the general-purpose corrosion-resistant grade, combining seawater and acid resistance with good strength — the usual choice for offshore and chemical duty. 600 is for high-temperature oxidation resistance in furnace and heat-treatment service. 718 is precipitation hardened for high strength up to around 700°C and is the standard choice for turbine and high-load fastener applications. Send us the medium, temperature and pressure and we will confirm.
- Why is Inconel so much more expensive than stainless steel?
- It is 50–72% nickel against 8–14% in austenitic stainless, and nickel is the dominant cost. Molybdenum and niobium additions raise it further, and the alloys are harder to melt, form and machine. Where the service genuinely demands it the whole-life cost is usually lower than repeatedly replacing failed stainless components.
- Is Inconel immune to chloride stress corrosion cracking?
- High-nickel alloys are effectively immune to the chloride stress corrosion cracking that affects austenitic stainless steels — this is a principal reason for specifying them in seawater and chloride-bearing service. They remain subject to other corrosion mechanisms, so the selection should always be made against the specific medium.
Send your Inconel requirement
Tell us the form, size, quantity and standard and our technical team will confirm stock and send a firm price. Minimum order quantity 5 kg, mill test certificates supplied as standard.