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- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Incoloy 800H vs Haynes 230 — Solid-Solution Strength for Fired Heater Service
Incoloy 800H (UNS N08810) and Haynes 230 (UNS N06230) compete for high-temperature fired-heater radiant-tube service. 800H is the iron-rich Fe-Ni-Cr economic standard; Haynes 230 is the W-strengthened Ni-Cr-W-Mo solid-solution alloy that delivers superior creep-rupture above 900°C and lower thermal expansion than 800H. Selection depends on tube wall thickness, cycling severity, and the cost-vs-life equation.
Need a quote on either alloy? Request RFQ or call +91-22-66157017. Material certs EN 10204 3.1 / 3.2 supplied.
Chemistry — UNS N08810 vs UNS N06230
Incoloy 800H is an iron-rich Fe-Ni-Cr alloy with controlled carbon and grain size to deliver creep performance. Haynes 230 is a nickel-base Ni-Cr-W-Mo solid-solution alloy with tungsten (W) 13 to 15 percent as the principal strengthener — W has a much larger atomic radius than Ni and produces strong lattice distortion strengthening that survives to very high temperature.
| Element | Incoloy 800H (N08810) | Haynes 230 (N06230) |
|---|---|---|
| Ni | 30.0 to 35.0 | 57.0 min (balance) |
| Fe | 39.5 min (remainder) | 3.0 max |
| Cr | 19.0 to 23.0 | 20.0 to 24.0 |
| W | not specified | 13.0 to 15.0 |
| Mo | not specified | 1.0 to 3.0 |
| La (rare earth) | not specified | 0.005 to 0.05 |
| Al | 0.15 to 0.60 | 0.20 to 0.50 |
| Ti | 0.15 to 0.60 | 0.10 max |
| C | 0.05 to 0.10 | 0.05 to 0.15 |
The tungsten content is the metallurgical differentiator. The lanthanum micro-addition (5 to 50 ppm) in Haynes 230 pins grain boundaries and improves cyclic oxidation resistance — a key driver for fired-heater radiant tubes that see daily startup-shutdown cycles. Full 800H chemistry tolerances are here.
Mechanical Properties — RT Through 982°C
| Property | Incoloy 800H | Haynes 230 |
|---|---|---|
| Tensile strength (RT, min) | 65 ksi / 450 MPa | 110 ksi / 760 MPa |
| 0.2 percent yield (RT, min) | 25 ksi / 170 MPa | 45 ksi / 310 MPa |
| Elongation (RT, min) | 30 percent | 40 percent |
| 100,000 hr rupture at 800°C | ~38 MPa | ~75 MPa |
| 100,000 hr rupture at 900°C | ~16 MPa | ~36 MPa |
| 100,000 hr rupture at 1000°C | ~6 MPa | ~14 MPa |
| Max sustained service temp | 982°C / 1800°F | 1149°C / 2100°F |
Haynes 230 also carries a lower mean coefficient of thermal expansion than 800H: roughly 12.7 vs 13.9 ppm/°C over the 25 to 800°C range. In cyclic fired-heater service that 5 to 10 percent reduction in thermal expansion translates to lower restraint stress and longer thermal-fatigue life. See the thermal expansion data for 800H.
Cost Ratio — Mill Stock
| Form | Incoloy 800H (baseline 1.0x) | Haynes 230 |
|---|---|---|
| Round bar | 1.0x | 1.6 to 1.9x |
| Seamless tube | 1.0x | 1.7 to 2.0x |
| Plate | 1.0x | 1.6 to 1.9x |
| Forgings | 1.0x | 1.9 to 2.2x |
Tungsten and rare-earth additions are the cost drivers in Haynes 230. Lead time is broadly comparable to other Ni-base premium alloys: 10 to 16 weeks mill-direct for non-stock sizes.
Service Envelope by Temperature
| Service Temperature | Preferred Alloy | Reason |
|---|---|---|
| Up to 815°C | Incoloy 800H | ASME Section VIII qualified, lowest mill cost |
| 815 to 900°C, low cycling | Incoloy 800H or 800HT | 800HT extends 800H envelope at minimal premium |
| 815 to 900°C, severe cycling | Haynes 230 | Lower CTE and rare-earth grain pinning improve thermal-fatigue life |
| 900 to 1050°C | Haynes 230 | W solid-solution + La pinning win on both creep and oxidation |
| Above 1050°C | Haynes 230 (to 1149°C ceiling) | 800H thermally exhausted; 230 still has useful strength |
Typical 800H wins: reformer pigtails, ASME Section VIII pressure vessels, ethylene-cracker convection coils, steam superheaters up to 815°C. Typical Haynes 230 wins: fired-heater radiant tubes (especially in cycling service), gas-turbine combustor liners, transition ducts, advanced ultra-supercritical boiler reheater tubes.
Decision Tree
Walk through the following questions:
- Sustained operating temperature? Below 815°C, default to 800H; above 950°C, default to 230.
- Number of cold-hot cycles per year? Above 200 cycles/year, 230 wins on thermal-fatigue life even at moderate temperature.
- Tube wall thickness? Thin-wall radiant tubes (Schedule 40 or below) benefit more from 230 because the lower thermal-expansion stress reduces tube bowing.
- Is the service ASME Section VIII? 800H allowables are well-tabulated; 230 requires Code Case 2063 review for pressure-bearing duty.
- Field replacement scenario? Replacing failed 800H tubes with 230 is straightforward provided the welding consumable matches the higher-alloy side (see FAQ below).
Applicable Standards
- Incoloy 800H: ASTM B407 / B408 / B409 / B514 / B515 / B564, ASME SB-407 through SB-564, ASME Section VIII Division 1 Code Case 1325, DIN 17460 Werkstoff 1.4876, NACE MR0175 / ISO 15156 (screened for sour service).
- Haynes 230: ASTM B435 (plate, sheet, strip), B564 (forgings), B572 (rod, bar, wire), B619 / B622 / B626 (welded and seamless pipe and tube), ASME SB-435 through SB-626, ASME Section I and Section VIII Division 1 Code Case 2063 (high-temperature pressure-bearing design).
- Common: EN 10204 3.1 or 3.2 mill cert, ASME Section IX welder qualification, AMS 5878 (Haynes 230 sheet for aerospace).
FAQs
Why does Haynes 230 contain tungsten when 800H does not?
Tungsten provides solid-solution strengthening with a larger atomic-radius mismatch than nickel-iron-chromium can deliver. The W atoms distort the gamma matrix lattice, blocking dislocation motion, which translates to roughly double the 100,000-hour creep-rupture strength of 800H at every temperature above 800°C. The trade-off is cost: tungsten is an LME-quoted strategic metal with significantly higher price volatility than nickel or chromium.
What welding consumable for Haynes 230 — ERNiCrWMo-1 or ERNiCr-3?
ERNiCrWMo-1 (Haynes 230-W filler, matching) for 230-to-230 joints and for any dissimilar joint where the weld sees 230-side service. ERNiCr-3 (Inconel 82 / 182) is the standard 800H-to-800H filler. For dissimilar 800H-to-230 welds, match to the higher-alloy side. The weld must survive the worst service condition the joint will see, so do not under-match.
Does Haynes 230 require post-weld stress-relieving?
Generally no. Haynes 230 is a solid-solution alloy without significant gamma-prime precipitation, so PWHT for stress relief is not metallurgically required. For thick-section pressure-bearing weldments (over 38 mm wall) some specifications require a post-weld solution-anneal at 1163 to 1232°C to dissolve carbides and restore the rare-earth grain-pinning structure. 800H is similar — PWHT is not metallurgically required for thin sections.
Can I replace failed 800H tubes with Haynes 230 in the same fired heater?
Yes, provided the headers and inlet / outlet flanges are reviewed. Haynes 230 has lower coefficient of thermal expansion than 800H (12.7 vs 13.9 ppm/°C), so mixing the two alloys in series will introduce expansion mismatch at the joint. Replacing a complete pass (header to header) avoids that. The welding consumable should match the higher-alloy side (ERNiCrWMo-1). Pressure design must be re-checked against ASME Code Case 2063 allowables — 230 allowables differ from 800H allowables across the temperature range.
Related
- Incoloy 800H vs Inconel 617
- Incoloy 800 vs 800H vs 800HT
- Incoloy 800H vs Inconel 625
- Incoloy 800H vs Inconel 600
- UNS N08810 specification
Ready to specify? TorqBolt QA-QC will quote either alloy with full mill certification (EN 10204 3.1 / 3.2), NACE compliance review, and lead-time confirmation. Send your spec or WhatsApp +91 22 66157017.
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