Hangbo Alloy Group
Shanghai · Est. 2012
A practical, data-driven comparison of nickel alloys and stainless steels — composition, corrosion resistance, temperature limits, strength, weldability and cost — to help engineers specify the right material for corrosive and high-temperature service.
Specifying the right material is one of the most consequential decisions in any corrosion- or heat-critical project. The recurring question our engineering customers ask is simple: when should I specify a nickel alloy instead of stainless steel? Both families are iron- or nickel-based, both rely on chromium for protective oxide films, and both are available as bars, plates, tubes, and forgings — but their chemistry-driven limits diverge sharply.
This guide compares the two families head-to-head and gives a clear decision framework. As a direct nickel alloy manufacturer and supplier, Hangbo Alloy Group stocks and produces Inconel, Hastelloy, Monel, Incoloy and related nickel alloys, and we help buyers decide between a cost-effective stainless grade and a higher-performing nickel alloy based on the real service environment.
The defining difference is the balance of iron and nickel. Stainless steels are iron-rich with chromium for passivation; nickel alloys put nickel first and use molybdenum, chromium, and sometimes copper or cobalt for specialized resistance. The table below shows typical nominal chemistry of representative grades across both families.
| Grade | Family | Ni % | Cr % | Fe % | Mo % | Other key |
|---|---|---|---|---|---|---|
| 304L | Austenitic SS | 8–10 | 18–20 | Balance | — | Low C |
| 316L | Austenitic SS | 10–14 | 16–18 | Balance | 2–3 | Low C |
| 310S | Austenitic SS | 19–22 | 24–26 | Balance | — | High Cr/Ni |
| 904L | Super-austenitic SS | 23–28 | 19–23 | Balance | 4–5 | 1.5 Cu |
| 254SMO / Alloy 926 | 6Mo SS | 17–20 | 19–21 | Balance | 6–6.5 | 0.2 N |
| Inconel 600 | Ni-Cr (SSS) | 72+ | 14–17 | 6–10 | — | — |
| Inconel 625 | Ni-Cr-Mo (SSS) | 58+ | 20–23 | 5 max | 8–10 | 3.2 Nb |
| Hastelloy C-276 | Ni-Mo-Cr (SSS) | Balance | 14.5–16.5 | 5 max | 15–17 | W, low C |
| Monel 400 | Ni-Cu | 63+ | — | 2.5 max | — | 28–34 Cu |
| Incoloy 825 | Ni-Fe-Cr | 38–46 | 19–23 | Balance | 2.5–3.5 | 1.5–3 Cu, Ti |
Rule of thumb: Once nickel content passes roughly 30% and iron drops below 50%, you are in true nickel-alloy territory — and that is where chloride and reducing-acid resistance take a step change upward.
Nickel alloys are denser than stainless but retain strength far better at temperature. The table contrasts typical room-temperature values of common grades (annealed, typical).
| Grade | Density (g/cm³) | Tensile (MPa) | Yield (MPa) | Useful Max Temp (°C) |
|---|---|---|---|---|
| 316L | 8.0 | 485–620 | 170–310 | ~870 (intermittent) |
| 310S | 7.9 | 515–720 | 205–310 | ~1100 |
| 254SMO (6Mo) | 8.0 | 650–850 | 300–450 | ~1000 |
| Inconel 600 | 8.4 | 550–700 | 240–400 | ~1150 |
| Inconel 625 | 8.4 | 830–1000 | 415–620 | ~980 (oxidizing) |
| Hastelloy C-276 | 8.9 | 790–1000 | 355–480 | ~1040 |
| Inconel 718 (aged) | 8.2 | 1275–1450 | 1035–1205 | ~650 (high strength) |
Precipitation-hardened grades (Inconel 718, Waspaloy, A-286) reach the highest strengths in both families, but nickel superalloys keep their margin at temperature where stainless steels soften.
Above about 600–700°C the gap widens dramatically. Stainless 310S performs well to ~1100°C in clean oxidizing air but is prone to sigma-phase embrittlement and carburization. Nickel alloys are engineered for exactly this regime:
For creep- and stress-rupture-limited components (turbine discs, furnace fixtures, reformer tubes), nickel alloys are effectively the only option.
This is where nickel alloys most often win the specification:
| Service Condition | Recommended First Choice | Upgrade to Nickel Alloy When… |
|---|---|---|
| Ambient, mild, oxidizing (food, architecture) | 304 / 304L | Rarely needed |
| Marine, mild acid, outdoor | 316L | Chloride SCC or pitting appears |
| Strong H₂SO₄ / HCl | Hastelloy C-276 / B-3 | Start here (316/904L fail) |
| Hot, chlorinated seawater | 6Mo SS (254SMO) | Biofouling + high velocity → Cu-Ni or 625 |
| Continuous >1000°C | Inconel 601/617, Haynes 230 | Stainless limited to ~870–1100°C |
| High-pressure, high-temp rotating | Inconel 718 / Waspaloy | Stainless lacks high-temp strength |
| Sour gas (H₂S/CO₂/Cl⁻) | Incoloy 925 / 825 (NACE) | More aggressive → C-276, 625 |
Hangbo Alloy Group manufactures and supplies both stainless and nickel alloys in a full range of forms, with mill test certificates and third-party inspection (SGS, TUV) available:
| Standard | Scope |
|---|---|
| ASTM A240 / A480 | Stainless steel plate, sheet, strip |
| ASTM A312 / A479 / A276 | Stainless pipe, bar, shapes |
| ASTM B168 / B443 | Inconel 600 / 625 plate & sheet |
| ASTM B575 | Hastelloy C-276 low-carbon Ni-Mo-Cr plate |
| ASTM B164 / B165 | Monel 400 rod, bar, pipe |
| ASTM B407 / B408 | Incoloy 800H/HT pipe & bar |
| NACE MR0175 / ISO 15156 | Sour (H₂S) service qualification |
| AMS, EN, W.Nr. | Aerospace, European & German designations |
Not sure whether your service needs a nickel alloy or an upgraded stainless grade? Our metallurgists will review your media, temperature, and pressure profile and recommend the most cost-effective certified material. As a direct manufacturer and supplier, we offer competitive price quotes, full material certification, and worldwide delivery.
Email: [email protected] | Phone / WhatsApp: +86-136-1165-6360
Stainless steel is iron-based (majority iron) with at least 10.5% chromium for passivation. A nickel alloy has nickel as the principal element (typically 30% to 70%+ Ni) with iron as a minor or balancing element. This chemistry gives nickel alloys far superior resistance to reducing acids, chlorides, and high-temperature oxidation than stainless steel, at a higher material cost.
Choose a nickel alloy when service involves strong reducing acids (hydrochloric, sulfuric), high chloride concentrations with pitting/crevice or stress-corrosion-cracking risk, flue-gas or seawater with hot, aggressive species, or continuous temperatures above roughly 650–800°C. For mild, ambient, oxidizing environments, 316L or a super-austenitic stainless is usually the cost-effective choice.
Nickel alloys are more corrosion resistant in reducing and chloride-rich environments. Hastelloy C-276 resists hydrochloric and sulfuric acid where even 316L fails; Inconel 625 resists pitting and crevice corrosion better than 316. Stainless steels remain excellent in mild oxidizing media, nitric acid, and clean atmospheric exposure at lower cost.
Austenitic stainless 310S is usable to about 1050–1100°C; most 300-series stainless are limited to ~870°C. Nickel alloys reach much higher: Inconel 601 to 1200°C, Inconel 617 and Haynes 230 to 1150–1200°C, and Alloy 602CA to 1200°C with superior oxidation and carburization resistance.
At room temperature, precipitation-hardening stainless (e.g., 17-4PH) and age-hardened nickel alloys (Inconel 718, Waspaloy) reach similar very high strengths. The key advantage of nickel alloys is retained strength and creep resistance at elevated temperature, where stainless steels lose strength rapidly above 600–700°C.
Nickel alloys typically cost 3 to 10 times more than 304/316 stainless on a per-kg basis because of high nickel and molybdenum content and more demanding melting practices (VIM/VAR/ESR). The total cost of ownership can still favor nickel alloys where failures, downtime, or corrosion allowance would otherwise dominate.
Yes, but dissimilar-metal joints require careful procedure. Inconel 625 (ERNiCrMo-3) or Inconel 82 (ERNiCr-3) filler metals are commonly used to weld nickel alloys to stainless and to carbon steel, controlling dilution and heat input to avoid precipitation and cracking.
Inconel 625 or Hastelloy C-276 replace 316L where chlorides cause pitting, crevice corrosion, or stress-corrosion cracking. For less severe seawater duty, 6Mo super-austenitic stainless (Alloy 926 / 254SMO) is a lower-cost intermediate step before moving to a full nickel alloy.
The principal families are solid-solution strengthened alloys (Inconel 600/601/617/625, Hastelloy C-series, Incoloy 800/825), precipitation-hardened superalloys (Inconel 718/725/X-750, Waspaloy, A-286), nickel-copper alloys (Monel 400/K-500), and copper-nickel alloys (90/10, 70/30) for seawater.
The most relevant comparisons are 304/304L (general), 316/316L (marine, mild acid), 310S (high heat), duplex 2205 (strength + chloride), and super-austenitics 904L, Alloy 20, and 6Mo (254SMO, Alloy 926) which bridge toward nickel alloys in aggressive service.
Most nickel alloys are austenitic and essentially non-magnetic in the solution-annealed condition, including Inconel, Hastelloy, and Incoloy grades. Monel 400 is also non-magnetic. Some iron-rich precipitation-hardened alloys may show slight magnetism after aging; ferritic and martensitic stainless steels are magnetic.
Hangbo Alloy Group supplies nickel alloys as round bars, forged blocks/discs/rings, seamless tubes and pipes, plates and sheets, precision strips, and welding wire/consumables, with mill test certificates and third-party inspection. Stainless equivalents are available through standard mill programs.
Stainless plate and pipe follow ASTM A240, A312, A479 and A276; nickel alloys follow ASTM B-series (B168 Inconel plate, B443 625, B575 C-276, B164 Monel, B407 Incoloy 800H) plus AMS, NACE MR0175/ISO 15156, and EN/W.Nr. designations. Both families are covered by ASME pressure-vessel codes.
Contact Hangbo Alloy Group at [email protected] or call/WhatsApp +86-136-1165-6360 with your grade, specification, form, size, and quantity. As a direct manufacturer and supplier we provide competitive price quotes, material certification, and worldwide delivery.
For help choosing between a nickel alloy and a stainless steel grade — or for a quotation on bars, plates, tubes, forgings, or welding consumables — contact Hangbo Alloy Group. We typically respond within 10 minutes and ship worldwide from our Shanghai facility.
Email: [email protected]
Phone: +86-136-1165-6360
WhatsApp: +86 13611656360
Send us your service conditions and we will recommend the most cost-effective nickel alloy or stainless grade, with a competitive quote and full certification.