Material comparison
Both are nickel-based superalloy brands — but they were developed to solve different engineering problems.
The short answer: Inconel is for temperature, Hastelloy is for acid. Both are nickel-based, both are expensive, and they solve different problems.
One point of confusion first. Hastelloy and Inconel are not alloy categories but trade names. Hastelloy is a registered trademark of Haynes International; Inconel, Incoloy and Monel are registered trademarks of Special Metals Corporation. Each brand covers dozens of grades, and those grades differ widely from one another.
Saying "let's use Hastelloy" is like saying "let's buy a German car". No order should be placed without the specific grade.
| Inconel (typical) | Hastelloy C series (typical) | |
|---|---|---|
| Base system | Nickel–chromium | Nickel–molybdenum–chromium |
| Chromium | 15 – 23% | 14 – 22% |
| Molybdenum | 0 – 10% | 12 – 17% |
| Headline property | Strength and oxidation resistance at temperature | Acid and pitting corrosion resistance |
| Service temperature | up to 1000 – 1200 °C | generally below 500 °C (X excepted) |
The decisive element is molybdenum. The Hastelloy C series carries more than twice as much of it, and that transforms resistance in reducing acids. High molybdenum does not, however, contribute to creep strength at high temperature.
Where they overlap: Inconel 625 resists both high temperature and corrosion and sits between the two worlds. If your environment is both hot and aggressive, 625 is usually the starting point.
Both families are tougher to machine than stainless steel: they work-harden rapidly and hold heat at the cutting edge. Rigid setups, sharp tools, positive feed and generous coolant are the usual requirements. For welding, matched filler is normal — ERNiCrMo-4 for C-276, ERNiCrMo-3 for 625. Interpass temperature control matters, and for the C series excessive heat input risks precipitation in the heat-affected zone.
| Trade name | UNS | W.Nr |
|---|---|---|
| Hastelloy C-276 | N10276 | 2.4819 |
| Hastelloy C-22 | N06022 | 2.4602 |
| Hastelloy B-3 | N10675 | 2.4600 |
| Hastelloy X | N06002 | 2.4665 |
| Inconel 600 | N06600 | 2.4816 |
| Inconel 601 | N06601 | 2.4851 |
| Inconel 625 | N06625 | 2.4856 |
| Inconel 718 | N07718 | 2.4668 |
Ordering against the UNS or W.Nr designation rather than the trade name avoids ambiguity and keeps the enquiry open to every qualified mill.
Not in the sense that usually matters. At room temperature their tensile strengths are comparable, but above roughly 600 °C Inconel grades retain far more of it. Hastelloy's advantage is chemical, not mechanical.
Yes. ERNiCrMo-3 or ERNiCrMo-4 filler is normally used, and the choice follows whichever side faces the more aggressive medium. Procedure qualification is still required.
Generally Hastelloy C-276, because of its high molybdenum content. As a rough guide C-276 runs at six to ten times 316L and Inconel 625 at five to seven times, though grade, form and quantity move those figures considerably.
No. They were developed for different failure mechanisms. Substituting one for the other without reviewing the service environment is a common and expensive mistake.
Send us the operating temperature, the medium and the pressure. We will come back with a material recommendation and the cost difference between the two options.
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