Hangbo Alloy Group
Shanghai · Est. 2012
Hastelloy C-276, C-22 and C-2000 look alike on paper but diverge in chromium, molybdenum, tungsten and copper — the exact balance that decides oxidizing versus reducing acid service. This comparison shows which one your process earns, with published UNS composition limits.
Hastelloy C-276, C-22 and C-2000 are the three workhorse C-type nickel-chromium-molybdenum alloys, and they are easy to confuse because they look almost identical on a data sheet and all weld without post-weld heat treatment in most fabrications. The differences are real, but they sit in the chromium, molybdenum, tungsten and copper balance — the same balance that decides whether your part survives in oxidizing acid, reducing acid, or the mixed streams that change chemistry during a batch.
This comparison tells you, grade by grade, what each alloy is best at, where the others beat it, and how to choose without overpaying for corrosion margin you do not need or under-buying and watching a heat exchanger leak. Every number below is a published ASTM/UNS composition limit; the corrosion behaviour is described qualitatively in the terms the alloy community uses, and your own service environment should always be confirmed against the applicable standard.
We make all three at Shanghai Hangbo Alloy Group Co., Ltd. from a virgin prime charge through VIM and then ESR or VAR remelting, so the comparison is not academic to us — it is a daily production decision about which route and which chemistry a customer's process actually earns. Our Hastelloy C-276 composition guide and the procurement pitfalls guide give the supporting detail.
If you read only one section, read "Which C-Type Should You Actually Buy": it maps the dominant acid regime in your process to the right alloy, and it is where most of the cost and risk decisions are made. The composition and corrosion tables above it are the evidence behind that choice, and the checklist at the end turns it into a purchase order you can send to any mill.
All three are solid-solution-strengthened Ni-Cr-Mo alloys with ultra-low carbon (0.010–0.015 max) and very low silicon, which is what makes them weldable without sensitization in the heat-affected zone. C-276 is the oldest and most widely stocked, biased toward molybdenum and tungsten for reducing-environment strength. C-22 raises chromium and lowers molybdenum for better behaviour in oxidizing acids. C-2000 pushes chromium to its highest and adds copper, aiming to be strong in both regimes at once. Think of them as points on one triangle: more molybdenum for reducing service, more chromium for oxidizing service, copper for sulfuric and mixed streams.
| Alloy | UNS | Lean toward | Trade-off |
|---|---|---|---|
| Hastelloy C-276 | N10276 | Reducing acids, broad familiarity | Less oxidizing-acid margin than C-22 |
| Hastelloy C-22 | N06022 | Oxidizing acids, wet chlorine | Less molybdenum than C-276 |
| Hastelloy C-2000 | N06200 | Both regimes plus sulfuric (Cu) | Newer, less ubiquitous in stock |
The published limits show the whole story. Chromium, molybdenum, tungsten and copper are the levers; everything else stays in a narrow band.
| Element (%, max unless a range) | Hastelloy C-276 (N10276) | Hastelloy C-22 (N06022) | Hastelloy C-2000 (N06200) |
|---|---|---|---|
| Nickel | Balance | Balance | Balance |
| Chromium | 14.5 – 16.5 | 20.0 – 22.5 | 22.0 – 24.0 |
| Molybdenum | 15.0 – 17.0 | 12.5 – 14.5 | 15.0 – 17.0 |
| Tungsten | 3.0 – 4.5 | 2.5 – 3.5 | — |
| Copper | — | — | 1.3 – 1.9 |
| Iron | 4.0 – 7.0 | 2.0 – 6.0 | 3.0 max |
| Cobalt | 2.5 max | 2.5 max | 2.0 max |
| Carbon | 0.010 max | 0.015 max | 0.010 max |
| Silicon | 0.08 max | 0.08 max | 0.08 max |
Two things stand out. First, C-2000 restores C-276's high molybdenum while lifting chromium to C-22's level and adding copper — which is why it is often described as combining the two. Second, tungsten appears only in C-276 and C-22; C-2000 drops it and leans on molybdenum and copper instead.
Pitting resistance equivalent number (PREN, taken as %Cr + 3.3×%Mo + 16×%N with nitrogen near zero here) puts C-2000 highest, then C-276, then C-22, because PREN rewards molybdenum and chromium. But PREN only predicts pitting in chloride; it says nothing about how an alloy handles a specific acid. The table below is the practical reading.
| Environment | C-276 | C-22 | C-2000 |
|---|---|---|---|
| Hydrochloric acid (reducing) | Excellent | Very good | Excellent |
| Sulfuric acid | Very good | Very good | Excellent (Cu helps) |
| Oxidizing acids (nitric, ferric chloride) | Good | Excellent | Excellent |
| Wet chlorine / bleach | Good | Excellent | Excellent |
| Mixed oxidizing-reducing streams | Very good | Very good | Excellent |
| Seawater / chloride pitting | Excellent | Very good | Excellent |
The pattern holds across the literature: C-22 is the oxidizing-acid choice, C-276 the broad reducing-environment default, and C-2000 the "both, plus sulfuric" option. For acid-specific detail see our hydrochloric acid guide and sulfuric acid guide.
All three weld readily by GTAW, GMAW and SMAW using matching or compatible nickel-molybdenum-chromium fillers, and all are low enough in carbon and silicon to avoid the intergranular precipitation that once plagued the older C-type alloys. Post-weld heat treatment is generally not required for corrosion service, though stress relief may be specified for certain fabricated geometries.
The practical ranking on weldability is effectively tied: C-22 and C-2000, with their slightly tighter low-carbon and low-silicon control, give the smallest heat-affected-zone precipitation tendency, while C-276's long service history means the widest filler and procedure knowledge base. For filler selection see our C-2000 welding wire guide and the broader nickel alloy welding guide.
As solid-solution alloys the three share similar strength and ductility in the solution-annealed condition, with typical room-temperature tensile strength in the high-700 to low-1000 MPa range depending on product form and specification. None is precipitation-hardenable; where you need age-hardening you are in Inconel 718 territory, not the C-types.
| Property | C-276 | C-22 | C-2000 |
|---|---|---|---|
| Strengthening mechanism | Solid solution | Solid solution | Solid solution |
| Typical solution-annealed tensile | High-700 to low-1000 MPa range | Similar range | Similar range |
| Upper service temperature | ~650°C continuous, higher intermittent | Similar | Similar |
| Precipitation hardenable? | No | No | No |
Above about 650°C the molybdenum-bearing C-types form brittle intermetallic phases over long exposure, so for sustained high-temperature load you should look at a different alloy family entirely — our C-276 vs Inconel 625 comparison covers where a higher-strength grade takes over.
The decision is mostly about which acid regime dominates and whether you must cover both. Use the guide below, then confirm against your exact concentrations and impurities.
| If your service is… | Choose | Reason |
|---|---|---|
| Broad reducing chemicals, familiar stock needed | C-276 | High Mo + W, deepest track record |
| Oxidizing acids, wet chlorine, bleach | C-22 | Highest Cr of the three |
| Sulfuric acid or mixed oxidizing/reducing | C-2000 | High Cr + Mo + Cu |
| One alloy must cover both regimes | C-2000 | Combines C-276 Mo with C-22 Cr |
| Price-sensitive, reducing only | C-276 | Usually the most available and economical |
Do not buy C-2000 for a pure reducing job that C-276 already covers, and do not buy C-276 for a wet-chlorine line where C-22 is clearly better. Matching the alloy to the worst-case chemistry is cheaper than a leak.
C-276 dominates flue-gas desulfurization, sour gas and general chemical process equipment where reducing conditions dominate. C-22 is common in bleach, pesticide and acid-chloride services and wherever nitric-leaning mixtures appear. C-2000 is specified where a single alloy must handle a process that swings between oxidizing and reducing — often in complex sulfuric-acid and specialty-chemical plants. All three are available from us as seamless tube and pipe, plate, bar and forgings.
C-276 is the most widely stocked of the three, which is often why it becomes the default even when C-22 or C-2000 would serve the process better — availability, not chemistry, drives the choice. C-22 and C-2000 are stocked less deeply, so lead time and minimum-mill quantities can be longer. The correct engineering answer sometimes has to wait for the correct alloy, and planning the order early removes the temptation to substitute.
| Alloy | Stock depth | Typical lead note |
|---|---|---|
| C-276 | Deepest, most distributors carry it | Often ex-stock in common sizes |
| C-22 | Good, less universal | Some sizes from mill |
| C-2000 | Shallower, newer grade | More often made to order |
For a one-off spares order, C-276's availability is a genuine advantage. For a new plant where the chemistry regime is oxidizing or mixed, specifying C-22 or C-2000 at the design stage — and letting us plan the melt — avoids a rushed substitution later. All three are available from our seamless tube and plate programme on a made-to-order basis.
Because the three look alike and share the C-type name, they are easily confused in stores and on the shop floor. The control is paperwork plus marking, not memory.
| Risk | Control |
|---|---|
| C-276 issued where C-22 was specified | Name UNS N10276 / N06022 / N06200 on every document |
| Off-cut mixed into the wrong bin | Colour or letter code plus heat number per piece |
| Welder grabs the wrong filler | Tie filler cert to the base grade; see our wire guides |
| PO says "C-type" loosely | Forbid generic terms; name the exact alloy |
Our C-276 vs C-22 corrosion comparison and the C-276 vs Inconel 625 comparison help lock the choice before any material is cut.
| Alloy | Product specs (examples) | Note |
|---|---|---|
| C-276 | ASTM B574 (bar), B575 (plate), B622 (seamless pipe), B564 (forgings) | See our C-276 vs C-22 comparison |
| C-22 | ASTM B574 / B575 / B622 family; UNS N06022 | full C-22 property guide |
| C-2000 | ASTM B574 / B575 / B622 family; UNS N06200 | full C-2000 property guide |
Always name the UNS number and the full ASTM or EN product specification with its edition on the purchase order, and require the melting route and EN 10204 certificate type so the grade you specify is the grade you receive.
This article is comparison guidance, not a substitute for corrosion testing in your own media. Alloy performance depends on exact concentrations, temperature, impurities and velocity; always verify against the current specification and, where consequence is high, against coupon testing.
Trademark note: Inconel, Hastelloy, Incoloy, Monel, Nimonic and Haynes are trademarks of their respective owners; the grades covered here are defined by their UNS numbers and the applicable ASTM or EN standards, not by the brand names.
It is not simply "better" — it is broader. C-2000 combines C-276's high molybdenum with C-22's high chromium and adds copper, giving it the highest pitting resistance of the three and strong behaviour in both oxidizing and reducing environments, especially sulfuric acid. For a pure reducing service that C-276 already covers, C-276 is usually the more available and economical choice.
Choose C-22 when your service leans oxidizing: nitric-acid mixtures, ferric chloride, wet chlorine and bleach environments, where its higher chromium (20–22.5 percent) gives better resistance than C-276's 14.5–16.5 percent chromium. For broadly reducing chemicals, C-276 remains the default.
Yes, for corrosion service they are welded without PWHT because their ultra-low carbon and silicon avoid heat-affected-zone sensitization. C-22 and C-2000 have the smallest precipitation tendency; C-276 has the largest proven procedure base. Stress relief may still be specified for certain fabricated geometries.
By PREN (chromium plus 3.3×molybdenum, nitrogen near zero), C-2000 is highest, then C-276, then C-22, because C-2000 pairs the highest chromium with C-276-level molybdenum. PREN predicts chloride pitting only; it does not rank behaviour in a specific acid.
C-2000 is the alloy designed to do that, with high chromium for oxidizing regimes and high molybdenum plus copper for reducing and sulfuric service. If your process chemistry swings between regimes, C-2000 usually removes the need to choose.
Only up to roughly 650°C in continuous service; beyond that the molybdenum-bearing C-types form brittle intermetallic phases over time. For sustained high-temperature load, a different family such as Inconel 625 or 718 is the better call.
Name the UNS number and the full ASTM or EN product specification with its edition, forbid equivalent substitution without written approval, require the melting route on the certificate, and require EN 10204 3.1 minimum (3.2 with witnessing for critical service). PMI at receiving confirms the major elements.
If you are deciding between C-276, C-22 and C-2000 for a specific process, send us your media, concentrations, temperature, and the product form and quantity you need. We will confirm which grade fits, quote our own virgin-material, double-melted production in the form you require, and supply the EN 10204 certificate and melting-route disclosure that prove the heat matches the grade. Typical response time is ten minutes, and we ship worldwide from Shanghai.
Email: serena@hangboalloy.com
Phone: +86 166 2109 2936
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Send us your media, concentrations, temperature and the product form and quantity you need. We will confirm whether C-276, C-22 or C-2000 is the right call, quote our own virgin-material, double-melted production in that grade, and supply the EN 10204 certificate and melting-route disclosure that prove the heat matches the grade.