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Hastelloy C276 has two different temperature ceilings: about 1040 °C (1900 °F) in dry oxidizing air, but only about 400–650 °C in wet, load-bearing corrosion service — because holding it between 650 °C and 1090 °C destroys its corrosion resistance.
The single most common mistake engineers make with C276 is treating it like a high-temperature alloy. It is not. Hastelloy C276 (UNS N10276) is a corrosion-resistant nickel-chromium-molybdenum-tungsten superalloy, not a creep-resistant high-temperature steel. Its chemistry was optimized to survive brutal chemical environments, not to hold load near a furnace. So the 'temperature limit' depends entirely on what you are asking the metal to do:
●Keep it dry and just need oxidation resistance? You can go high — near 1040 °C.
●Keep it wet, corrosive, and stressed? You must stay low — roughly 400 °C, and never dwell above 650 °C.
Always read a C276 temperature number with that distinction in mind. The rest of this guide expands each side of the limit and shows how to apply it. Background on the alloy itself is in our overview of what Hastelloy C276 is and its chemical composition.
In dry, oxidizing air C276 resists scaling to roughly 1040 °C (1900 °F) for continuous service, with short-duration tolerance a little higher; above that it oxidizes too fast to be practical.
Oxidation resistance comes from chromium, which forms a protective oxide film on the surface. C276 carries 14.5–16.5% chromium plus molybdenum and tungsten, so in moving air it holds a stable scale to about 1040 °C. Several reference sources cite the continuous-service top end near 1038–1040 °C, with short exposures accepted slightly higher.
Important: 'oxidation limit' only tells you the metal will not burn away. It says nothing about corrosion resistance or load-bearing ability in that band. In fact, sitting near 1040 °C pushes C276 deep into its sensitization range (see Section 4), so a part used that hot for corrosion service would fail for the wrong reason.
For high-heat structural jobs, compare C276 with Inconel 625, which is often preferred where both heat and corrosion matter.
For wet, corrosive duty where you must keep full corrosion resistance, treat about 400 °C (750 °F) as the practical ceiling, and treat 650 °C (1200 °F) as the hard line you must never cross.
Most C276 parts live in liquids or vapors that are hot but corrosive — acid, chloride brine, flue-gas condensate. In that world the limiting factor is not melting or scaling; it is the precipitation of brittle intermetallic phases that begins above ~650 °C. Below that, the alloy stays in its safe, single-phase condition.
A useful working rule quoted across fabrication references:
● 0 °C to 650 °C: the normal, routine band for chemical-process service with excellent corrosion resistance.
● ~400 °C: a conservative ceiling often cited for sustained wet-corrosion duty where you want maximum margin.
● 650–1090 °C: forbidden for corrosion-critical parts — precipitation here is irreversible without a full solution anneal.
See our Hastelloy C276 corrosion resistance guide for how temperature combines with acid concentration and chlorides.
Above ~650 °C (1200 °F) C276 precipitates brittle intermetallic phases — mainly μ-phase, plus M6C carbides and P-phase — at the grain boundaries; these deplete the surrounding metal of chromium and molybdenum and make it corrode and crack easily.
Picture the alloy as a carefully balanced solution. Heat it into the 650–1090 °C window for long enough and the molybdenum, tungsten, and carbon start to clump together along the crystal boundaries as hard, brittle particles. The zones next to those particles lose their protective elements, so corrosion can run along the grain boundaries — intergranular attack — like a seam unraveling.
The consequences are concrete:
● Loss of intergranular and localized (pitting, crevice) corrosion resistance.
● Lower ductility and impact toughness — the part becomes brittle.
● The damage is 'locked in' unless you perform a full solution anneal at 1120–1180 °C and rapid-quench it.
This is exactly the same reason welding keeps interpass temperature low and why post-weld heat treatment is handled carefully — see the
C276 is usable down to at least -196 °C (-320 °F, liquid nitrogen) with no brittle transition, because its face-centered-cubic (austenitic) crystal structure stays tough at low temperature.
Ferritic and martensitic steels can turn brittle and shatter at cryogenic temperatures — the ductile-to-brittle transition. C276 does not have that problem. Its FCC structure remains ductile all the way down, and measured Charpy impact values stay above 100 J even at -196 °C. That is why C276 is chosen for LNG, liquefied-gas transfer, and cryogenic process lines.
Codes recognize this: ASME Section VIII, Division 1 permits C276 in cryogenic pressure vessels without impact-testing requirements, because the material is inherently tough when cold. For the full low-temperature design picture, pair this with the
mechanical properties data.
For Section VIII, Division 1 pressure service, C276 design stress values are published for roughly -198 °C to 427 °C (-325 °F to 800 °F); the exact allowable stress comes from ASME Section II, Part D for the relevant product form and temperature.
When you size a pressure vessel or pipe, you do not pick a temperature from a marketing brochure — you use the code allowable stress. For C276 plate (ASTM B575 / ASME SB-575) and the related product forms, ASME lists design stresses from cryogenic temperatures up to about 427 °C. Above that band the code allowable drops sharply because creep and precipitation dominate.
Practical takeaways for designers:
● Look up the allowable stress for your exact product form and temperature in ASME Section II, Part D.
● Do not specify C276 for sustained stressed service above ~427 °C expecting code allowable stress to carry you — it will not.
● For cryogenic vessels, rely on the code's recognition that C276 needs no impact testing when solution-annealed.
The governing specifications are summarized in our ASTM standards for Hastelloy C276 article.
C276 keeps useful strength to several hundred degrees, but above about 500 °C creep (slow, time-dependent deformation) becomes design-relevant, so pressure parts must be sized by code allowable stress and stress-rupture data, not by room-temperature strength.
Like all metals, C276 gets weaker as it gets hotter. Representative stress-rupture values for annealed material (the stress that causes failure after a given time) illustrate the trend:
Temperature | 1000-hour rupture stress | 10,000-hour rupture stress |
649 °C (1200 °F) | ~179 MPa | ~138 MPa |
760 °C (1400 °F) | ~97 MPa | ~62 MPa |
871 °C (1600 °F) | ~35 MPa | ~17 MPa |
Below ~500 °C, creep is not the limiting factor for process piping, and standard ASME B31.3 allowable stresses already include safety margins. Above it, you must design for long-term creep and rupture. The key message: the oxidation limit (1040 °C) is not the design limit for a load-carrying part.
Full strength and modulus data are in the mechanical properties guide.
In oxidizing media (air, nitric acid, wet chlorine) C276's chromium film protects it to higher temperatures; in reducing acids (hydrochloric, sulfuric) the temperature limit is set by the acid, not the metal — often only 80–120 °C for concentrated HCl.
This is the second big distinction after 'dry vs wet.' Corrosion resistance depends on the environment:
● Oxidizing service: chromium forms a stable passive film; C276 performs well to several hundred °C in nitric acid and similar media.
● Reducing acid service: resistance comes from molybdenum and tungsten, not chromium. In hot concentrated hydrochloric acid the practical working temperature is typically 80–120 °C regardless of the metal's melting point.
So 'what is the temperature limit?' has no single answer without the chemical. Always pair the temperature with the specific acid, concentration, and chloride level.
For media-specific limits see Hastelloy C276 for acid service and Hastelloy C276 corrosion resistance.
C276 and Inconel 625 share a high oxidation ceiling and cryogenic floor; Alloy 20, 904L, and Incoloy 825 are lower-temperature stainless-family alloys with tighter wet-service ceilings. Pick by environment, not by a single temperature number.
The table gives approximate, code-check-required comparisons. 'Sensitization threshold' is the temperature above which harmful precipitation begins.
Alloy | Continuous oxidizing max | Wet/corrosion ceiling | Sensitization threshold | Cryogenic min |
Hastelloy C276 | ~1040 °C | ~400 °C (keep corrosion) | >650 °C (μ/M6C) | -196 °C |
Inconel 625 | ~980–1093 °C | good to ~650 °C (Cr-rich) | >650 °C (higher stability) | -196 °C |
Alloy 20 | ~815 °C | ~425 °C | carbides ~540–760 °C | limited to -196 °C |
904L | ~400–450 °C | ~400 °C | carbides 425–870 °C | -196 °C |
Incoloy 825 | ~650 °C | ~540 °C (1000 °F) | ~540–760 °C | -196 °C |
C276 and 625 overlap heavily; 625 is often chosen where high-temperature strength plus chloride/sour-gas resistance matter, while C276 wins on universal severe corrosion. The stainless-family alloys (20, 904L, 825) are cheaper but must stay cooler and avoid the harshest acids.
Detailed comparisons: C276 vs Inconel 625, C276 vs Alloy 20, C276 vs 904L, C276 vs Incoloy 825.
Welding must respect the same ~650–1100 °C danger zone: keep interpass temperature at or below 150 °C, control heat input, and never apply intermediate stress-relief heat treatment in the sensitization range.
Every weld reheats a band of base metal into a small version of the sensitization window. Good procedure keeps that band brief and cool enough that precipitates do not form:
● Interpass temperature: ≤150 °C (300 °F), lower for critical acid service.
● Heat input: ~0.5–1.5 kJ/mm; keep it in the middle of the range.
● Root back-purge with argon to avoid internal oxidation.
● Post-weld heat treatment: generally not required; if specified, only a full solution anneal above 1120 °C.
Fabrication that ignores these rules can sensitize the HAZ even if the design temperature was perfectly safe. The welding guide covers filler selection (ERNiCrMo-4) and the full procedure.
Across the main C276 applications the temperature ceiling is set by the chemical, not the alloy: acids stay cool (often <120 °C), while FGD, chemical-plant, and pulp & paper service run warmer but still below the 650 °C line.
Typical service temperatures by sector (verify against your exact stream):
● Acid service (HCl, H2SO4): usually 80–120 °C for concentrated acids; C276 is chosen precisely because it survives where stainless cannot.
● FGD systems: warm, acidic, chloride-rich flue-gas condensate — C276 is used at the hottest, most aggressive inlet and wet/dry zones, well under 650 °C.
● Chemical plants: reactor and heat-exchanger duty in the normal 0–650 °C band; C276 handles mixed oxidizing/reducing streams other alloys cannot.
● Pulp & paper: bleaching (chlorine dioxide, hypochlorite) environments where C276's resistance holds at the process temperatures used.
Sector deep-dives: C276 for acid service, C276 for FGD systems, C276 for chemical plants, C276 for pulp & paper.
Q: Can Hastelloy C276 be used at 700 degrees C for load-bearing service?
A: Using C276 for sustained load-bearing service at 700 degrees C is not recommended. Although the alloy can survive short-term exposure in air up to 1040 degrees C, at 700 degrees C it experiences both intermetallic phase precipitation (mu/P phases) over time and inadequate creep strength (approximately 80 MPa for 1000-hour stress-rupture). For continuous structural use above 650 degrees C, Inconel 625 (with gamma-double-prime strengthening) or Hastelloy X is the better choice. C276 is acceptable at 700 degrees C only for non-load-bearing or very low-stress applications with minimal sustained exposure.
Q: What happens if C276 is heated to 800 degrees C by mistake during fabrication?
A: If C276 is heated to 800 degrees C (a temperature in the forbidden 600-900 degrees C range) during fabrication such as hot bending or improper stress relief, mu phase and P phase will precipitate, causing severe embrittlement (impact toughness dropping from greater than 200 J to below 30 J) and localized loss of corrosion resistance. The good news is that this damage is fully reversible: a solution anneal at 1120-1175 degrees C followed by rapid water quench will dissolve the precipitated phases and restore the original properties. Any component heated into this range should be re-annealed before being placed in corrosive service.
Q: Is Hastelloy C276 suitable for liquid nitrogen or LNG service?
A: Yes, C276 is excellent for cryogenic service. It has a fully austenitic FCC structure with no ductile-to-brittle transition, retaining Charpy impact energy above 130 J at minus 196 degrees C (liquid nitrogen) and above 150 J at minus 162 degrees C (LNG). It is commonly used for LNG plant valves, flanges, and instrumentation where both cryogenic toughness and resistance to chloride-containing condensed phases are required. The main design consideration is thermal contraction (11.2 x 10-6 per K), which should be accounted for in joint design.
Q: Why does C276 have a lower ASME allowable stress temperature limit (427 degrees C) than its physical maximum (1040 degrees C)?
A: The 1040 degrees C figure is the physical oxidation-limited maximum in air, relevant only for components that do not carry mechanical load. The 427 degrees C (800 degrees F) ASME limit is the highest temperature for which the code publishes allowable stress values for C276 in the solution-annealed condition. Above 427 degrees C, ASME does not provide design stresses because the available creep and long-term property data become insufficient for safe code-based design. It is not a metallurgical failure temperature but a code-data boundary; engineers needing service between 427 and 650 degrees C must use tested creep data with code case approval or select a high-temperature-grade alloy.
Q: Can C276 be used in sulfur recovery unit (SRU) service at 500 degrees C?
A: No, C276 should not be used in sulfur recovery unit service at 500 degrees C. Elemental sulfur and H2S at this temperature will cause severe sulfidation because nickel reacts with sulfur above approximately 450 degrees C to form low-melting nickel sulfides that penetrate grain boundaries. The safe upper limit for C276 in sulfur-containing environments is about 400-450 degrees C. For SRU thermal oxidizer outlets and sulfur pits where temperatures exceed 450 degrees C, refractory-lined carbon steel or high-silicon cast irons are more appropriate; C276 may be used in the cooler downstream sections below 400 degrees C.
Q: Does welding affect the temperature limits of C276?
A: Welding itself does not change the base metal temperature limits as long as the proper procedure is followed: ERNiCrMo-4 or ERNiCrMo-10 filler, heat input 0.5-1.5 kJ/mm, interpass below 93 degrees C, and no post-weld heat treatment in the 600-900 degrees C range. The heat-affected zone (HAZ) briefly reaches high temperatures during welding, but because the peak temperature is localized and the cooling is rapid, no harmful precipitation occurs if interpass is controlled. However, if a thick welded component requires stress relief, the forbidden 600-900 degrees C range means only a full solution anneal (1120-1175 degrees C, water quench) is acceptable, never a partial stress relief.
