Incoloy 800 (UNS N08800) – High-Temperature Fe-Ni-Cr Alloy Supplier of Round Bars, Tubes & Plates | Shanghai Hangbo Alloy Group
Date: 2026年7月23日 Categories: News Views: 287
By Shanghai Hangbo Alloy Group Co., Ltd. | ISO 9001:2015 Certified | Est. 2012 | Shanghai, China
Contact: sales@hangboalloy.com | hangbo@nickel-alloy.com | WhatsApp: +86 13611656360
Quick Answer: What Is Incoloy 800?
Incoloy 800 (UNS N08800 / W.Nr. 1.4876) is an iron-nickel-chromium solid-solution alloy with approximately 32% nickel and 21% chromium that delivers reliable oxidation, carburization, and nitridation resistance at temperatures up to 815°C (1500°F) at a lower cost than nickel-base alloys like Inconel 600. It is specified to ASTM B163 (tube), B407 (pipe), B408 (bar), and B409 (plate) and widely used in petrochemical furnace tubing, heat exchangers, and nuclear steam generator components. Shanghai Hangbo Alloy Group supplies Incoloy 800 as round bars, seamless tubes, and plates with full EN 10204 3.1 certification.
Industry Pain Point: Heat exchanger specifiers frequently default to 304/316 stainless for the cold end of process heaters and then encounter chloride SCC cracking within 18–36 months because the tube-wall temperature at the hot end is 40–60°C higher than the bulk process temperature — exceeding the 60°C SCC threshold for austenitic stainless. Incoloy 800, with its 32% nickel content providing immunity to chloride SCC below ~150°C and oxidation resistance to 815°C, eliminates this failure mode at roughly 1.5–2× the cost of 316L — far less than the 5–8× premium for Inconel 600.
Key Properties at a Glance
| Property | Value |
|---|---|
| UNS Number | N08800 |
| W.Nr. | 1.4876 |
| Alloy Family | Fe-Ni-Cr (Incoloy) |
| Density | 7.94 g/cm³ (0.287 lb/in³) |
| Melting Range | 1357–1385°C (2475–2525°F) |
| Max Continuous Service Temp. | ~815°C (~1500°F) |
| Tensile Strength (RT, Annealed) | ≥ 520 MPa (≥ 75 ksi) |
| Yield Strength (RT, Annealed) | ≥ 205 MPa (≥ 30 ksi) |
| Elongation (RT, Annealed) | ≥ 30% |
| Thermal Conductivity (20°C) | ~11.5 W/m·K |
| Key Standards | ASTM B163, B407, B408, B409, B564 |
Product Overview
Incoloy 800 is the economy-class workhorse of the high-temperature alloy fleet — a deliberately iron-rich (≥39.5% Fe) composition that uses nickel only where it provides the highest return on investment: as an austenite stabilizer (maintaining FCC structure through all temperatures, eliminating the phase-transformation stresses that plague ferritic steels) and as the key alloying element providing chloride stress-corrosion cracking resistance and carburization resistance.
The alloy occupies a commercially important middle ground: it costs significantly less than Inconel 600 (~32% Ni vs. ~72% Ni) while outperforming stainless steels across three dimensions critical to process heater and heat exchanger reliability:
- Chloride SCC resistance: The 30–35% nickel content provides effective immunity to chloride stress-corrosion cracking at temperatures up to approximately 150°C — the dominant failure mode that limits 304/316 stainless heat exchangers to chloride concentrations below ~100 ppm. This single property is the most common reason Incoloy 800 is selected over stainless steels.
- Oxidation resistance to 815°C: The 19–23% chromium content forms a protective Cr₂O₃ scale that resists oxidation and carburization in combustion gas atmospheres. The scale remains adherent through thermal cycling because the alloy's thermal expansion coefficient (14.4 μm/m·°C) closely matches the oxide — unlike ferritic stainless steels where CTE mismatch causes spallation.
- Resistance to sigma-phase embrittlement: The high nickel content suppresses sigma-phase formation in the 600–900°C range that would embrittle standard austenitic stainless steels after extended service.
800 vs. 800H vs. 800HT — the family distinction: Incoloy 800 is the general-purpose grade with carbon ≤0.10%. Incoloy 800H is the controlled-carbon variant (0.05–0.10% C) with mandatory high-temperature annealing (≥1100°C) for optimized creep strength in ASME Section VIII pressure vessel service above 593°C. Incoloy 800HT adds aluminum-plus-titanium control (0.85–1.20% combined) for grain-size stabilization at the finest end of the spectrum, providing the best creep rupture properties of the three. Shanghai Hangbo Alloy Group stocks all three variants.
Executive Standards
| Product Form | ASTM | ASME | EN / W.Nr. |
|---|---|---|---|
| Round Bar & Rod | ASTM B408 | ASME SB-408 | EN 10095 / 1.4876 |
| Seamless Tube | ASTM B163 | ASME SB-163 | EN 10216-5 |
| Seamless Pipe | ASTM B407 | ASME SB-407 | EN 10216-5 |
| Plate, Sheet & Strip | ASTM B409 | ASME SB-409 | EN 10095 |
| Forgings | ASTM B564 (UNS N08800) | ASME SB-564 | — |
| Welded Pipe | ASTM B514 / B515 | ASME SB-514 / SB-515 | — |
| Wire | ASTM B408 | — | — |
Chemical Composition (wt.% per ASTM B408 – 100% OES Verified)
| Element | Min | Max | Role in Incoloy 800 |
|---|---|---|---|
| Nickel (Ni) | 30.0 | 35.0 | Austenite stabilizer; provides chloride SCC resistance and carburization resistance |
| Chromium (Cr) | 19.0 | 23.0 | Forms protective Cr₂O₃ scale for oxidation and carburization resistance to 815°C |
| Iron (Fe) | ≥ 39.5 | Balance | Matrix element; high Fe content is the primary cost-reduction strategy vs. Inconel 600 |
| Carbon (C) | — | 0.10 | Kept moderate; unlike 800H (0.05–0.10%), 800 has no lower carbon bound |
| Manganese (Mn) | — | 1.50 | Deoxidizer; austenite stabilizer |
| Silicon (Si) | — | 1.00 | Deoxidizer; minor oxidation resistance benefit |
| Aluminum (Al) | 0.15 | 0.60 | Residual deoxidizer; contributes to oxidation resistance |
| Titanium (Ti) | 0.15 | 0.60 | Minor carbide former; stabilizes carbon against chromium depletion |
| Copper (Cu) | — | 0.75 | Incidental; kept low to avoid hot shortness |
| Sulfur (S) | — | 0.015 | Preserves hot workability |
800 vs. 800H vs. 800HT compositional differences:
| Element | Incoloy 800 | Incoloy 800H | Incoloy 800HT |
|---|---|---|---|
| Carbon (C) | ≤ 0.10 | 0.05–0.10 | 0.06–0.10 |
| Al+Ti Combined | Not specified | Not specified | 0.85–1.20 |
| Grain Size | Not specified | ASTM 5 or coarser | ASTM 5 or finer |
| Solution Anneal | 980–1065°C | ≥ 1100°C (mandatory) | ≥ 1100°C (mandatory) |
| Primary Application | General high-temperature | ASME pressure vessels above 593°C | Maximum creep rupture life |
Mechanical & Physical Properties
Room-Temperature Mechanical Properties (Solution-Annealed, 980–1065°C)
| Property | Value | Standard |
|---|---|---|
| Tensile Strength (Rm) | ≥ 520 MPa (≥ 75 ksi) | ASTM B408 |
| Yield Strength 0.2% (Rp0.2) | ≥ 205 MPa (≥ 30 ksi) | ASTM B408 |
| Elongation (A5, 50 mm) | ≥ 30% | ASTM B408 |
| Hardness | 75–90 HRB (typical) | — |
| Young's Modulus (20°C) | 196 GPa (28.4 × 10³ ksi) | — |
Elevated-Temperature Tensile Properties (Typical, Annealed)
| Temperature | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |
|---|---|---|---|
| 20°C | 560 | 240 | 35 |
| 400°C (752°F) | 480 | 160 | 32 |
| 600°C (1112°F) | 380 | 130 | 35 |
| 700°C (1292°F) | 240 | 110 | 40 |
| 815°C (1499°F) | 140 | 80 | 55 |
Key note on elevated-temperature strength: Incoloy 800 is a solid-solution-strengthened alloy with no precipitation hardening. Its strength at temperatures above 600°C is significantly lower than nickel-base alloys (Inconel 600 retains ~300 MPa at 700°C vs. 240 MPa for Incoloy 800). For ASME pressure vessel applications above 593°C (1100°F), the Code requires use of Incoloy 800H with mandatory high-temperature anneal (≥1100°C) rather than standard 800.
Physical Properties
| Property | at 20°C | at 200°C | at 600°C | Unit |
|---|---|---|---|---|
| Density | 7.94 | — | — | g/cm³ |
| Thermal Conductivity | 11.5 | 13.5 | 20.0 | W/m·K |
| Specific Heat | 460 | 490 | 565 | J/kg·K |
| Electrical Resistivity | 0.99 | 1.06 | 1.14 | μΩ·m |
| Mean Thermal Expansion (20°C–T) | — | 14.4 | 16.2 | μm/m·°C |
Heat Treatment
Solution Annealing
| Parameter | Specification |
|---|---|
| Temperature | 980–1065°C (1800–1950°F) |
| Soak Time | Minimum 15–30 minutes for light sections; 1 hour per 25 mm for sections ≥ 25 mm |
| Cooling Method | Air cool or water quench — either is acceptable |
Critical distinction from 800H/800HT: For standard Incoloy 800, the solution annealing temperature range (980–1065°C) is deliberately lower than 800H/800HT (which require ≥1100°C). This is because 800 is not intended for ASME Section VIII Division 1 service above 593°C — the lower anneal temperature is adequate for general corrosion and oxidation applications and preserves a finer grain size for improved room-temperature strength.
Stress Relief
| Parameter | Specification |
|---|---|
| Temperature | 540–650°C (1000–1200°F) |
| Soak Time | 1–2 hours |
| Cooling | Air cool |
Annealing After Cold Work
For cold-worked components that will operate above 540°C, re-anneal at 980–1065°C to prevent stress-assisted chromium depletion (sensitization) that could occur if residual cold work accelerates carbide precipitation.
No precipitation hardening: Incoloy 800 is strictly solid-solution strengthened. The aluminum and titanium at 0.15–0.60% each are insufficient to form a γ′ precipitate volume fraction — this is a deliberate decision that distinguishes the 800 series from the age-hardenable Incoloy A-286.
Production Process
1. Round Bars & Forgings
- Melting: EAF (Electric Arc Furnace) + AOD (Argon Oxygen Decarburization) or VIM for premium quality. The high iron content (~42% Fe) makes EAF melting cost-effective without the stringent vacuum requirements of nickel-base alloys.
- Hot Forging / Rolling: Ingot or continuously cast billet heated to 1150–1200°C. Forged or hot-rolled to bar with minimum 4:1 reduction. Finishing temperature ≥ 900°C. The high iron content reduces hot strength compared to Inconel 600, allowing lower forging press tonnage.
- Solution Annealing: 980–1065°C, air cool or water quench. For bars designated for machining into ASME pressure-retaining components above 593°C, specify Incoloy 800H with mandatory ≥1100°C anneal.
- Straightening, UT & Finishing: Multi-roll straightening. Ultrasonic testing per ASTM B408 / ASTM A388 for bars ≥ Ø50 mm. PMI (XRF) on every piece — nickel content (30–35%) is the rapid grade verification criterion.
2. Seamless Tubes & Pipes
- Hollow Preparation: Hot-pierced or hot-extruded from annealed billet at 1150–1200°C — lower than Inconel 600 extrusion temperature (~1175–1225°C) because the lower nickel content reduces hot strength.
- Cold Pilgering / Drawing: Multi-pass cold reduction (30–60% typical) with intermediate solution anneals. The lower work-hardening rate vs. Inconel 600 allows larger cold reductions per pass with fewer intermediate anneals.
- Final Annealing: 980–1065°C, air cool or bright anneal in hydrogen for surface-critical applications. Tubes for heat exchanger service may be ordered in the annealed-and-pickled condition to provide a clean, passive surface for service.
- Testing: 100% hydrostatic or eddy current per ASTM E426. Destructive tensile testing per heat. Flattening and flaring tests per ASTM B163. Intergranular corrosion testing (ASTM A262 Practice C or E) available on request for nitric acid service.
3. Plates, Sheets & Strips
- Hot Rolling: Slab heated to 1150–1200°C, multi-pass hot rolling with finishing temperature ≥ 900°C.
- Solution Annealing: 980–1065°C, air cool. Continuous roller-hearth furnace preferred for sheet ≤ 3 mm gauge for temperature uniformity.
- Leveling & Cutting: Precision leveling. Plasma, abrasive waterjet, or shear cutting.
- Surface & NDE: Pickling + passivation per ASTM A380. 100% visual inspection. Ultrasonic testing per ASTM A435 on request.
Industry Applications
| Industry | Typical Component | Why Incoloy 800? |
|---|---|---|
| Petrochemical — Process Heaters | Convection-section tubes, transfer line exchangers, quench boiler tubes | Oxidation/carburization resistance to 815°C at lower cost than Inconel 600; chloride SCC immunity eliminates 316L failures |
| Nuclear — PWR Steam Generators | Steam generator tubing, moisture separator reheaters | Resists chloride SCC and caustic intergranular attack in secondary-side water chemistry; 40-year operating history in nuclear plants worldwide |
| Nitric Acid Production | Cooler-condenser tubes, tail-gas heater tubes | Resists nitric acid + NOx condensing environments where stainless steels suffer intergranular attack from sensitization |
| Heat Treatment Furnaces | Radiant tube muffles, retorts, baskets, trays | Carburization resistance in endothermic gas atmospheres at 800–900°C |
| Chemical — Ethylene | Quench boiler tubes, transfer line heat exchangers | Resists carburization + thermal cycling from 850°C (gas) to 200°C (water/steam) across tube wall |
| Food Processing — Edible Oil | Deodorizer heating coils, fatty acid distillation | Resists hot fatty acids + trace chlorides; nickel content below 35% avoids nickel-leaching concerns in food contact |
Quality Assurance: 7-Stage Zero-Defect Inspection
- Raw Material Verification: Incoming ferrochrome, nickel, and iron charge materials analyzed by OES. Chromium source verified to contain ≤0.03% P — phosphorus from low-grade ferrochrome can elevate the melt P above 0.015% and reduce hot workability.
- Melt Chemistry: In-process chemistry check after AOD/VIM refining. Nickel and chromium verified within specification. Carbon verified ≤0.10% by combustion analysis. Sulfur ≤0.012% internal target (tighter than 0.015% spec) for enhanced hot workability margin.
- Hot Working Surveillance: Infrared pyrometry on forging and rolling operations. Reduction ratio verified ≥4:1. Finishing temperature ≥900°C — processing charts archived per heat number.
- Solution Anneal Verification: Digital furnace chart ±5°C accuracy. Rapid hardness check (HRB) — hardness 75–90 HRB confirms proper anneal; hardness >95 HRB indicates residual cold work or insufficient temperature and triggers re-anneal.
- Destructive Mechanical Testing (Per Heat/Lot): Room-temperature tensile per ASTM E8. Intergranular corrosion test per ASTM A262 Practice C (Huey test, boiling 65% HNO₃) or Practice E (copper-copper sulfate-sulfuric acid) on request, particularly for nitric acid or nuclear service.
- Non-Destructive Examination: 100% UT per ASTM B408 / ASTM A388 for bars ≥Ø50 mm. 100% eddy current or hydrostatic for tubes. Dimensional verification and PMI on every piece. Surface roughness Ra ≤3.2 μm for heat exchanger tubing.
- Documentation & Shipment: EN 10204 Type 3.1 Mill Test Certificate with full chemistry, tensile results, grain size, and NDE summary. Third-party inspection by SGS, Bureau Veritas, TÜV Rheinland, or authorized nuclear inspection agencies (for ASME Section III applications) available.
Frequently Asked Questions
Q1: What is Incoloy 800 used for?
Incoloy 800 is used for petrochemical process heater convection-section tubes, nuclear PWR steam generator tubing, nitric acid cooler-condensers, heat treatment furnace radiant tubes, ethylene quench boilers, and edible-oil deodorizer heating coils. It is selected where the combined requirements are: (a) oxidation or carburization resistance to 815°C, (b) chloride SCC resistance superior to stainless steels, and (c) cost substantially below Inconel 600 — the alloy's high iron content (~42%) is the economic enabler.
Q2: What is the density of Incoloy 800?
7.94 g/cm³ (0.287 lb/in³) — approximately 6% lighter than Inconel 600 (8.47 g/cm³) due to the higher iron content replacing nickel. This translates to 6% less material weight for a given tube length — a meaningful cost advantage in large heat exchanger bundles containing 5,000+ tubes.
Q3: What is the maximum service temperature of Incoloy 800?
Approximately 815°C (1500°F) for continuous service. The limiting factor is oxidation — the protective Cr₂O₃ scale begins to thin and may exhibit breakaway oxidation above ~850°C. For ASME pressure vessel applications above 593°C, the Code requires use of Incoloy 800H (controlled carbon + mandatory ≥1100°C anneal) rather than standard 800 to ensure adequate creep strength.
Q4: What is the melting point of Incoloy 800?
The melting range is 1357–1385°C (2475–2525°F). The narrow 28°C melting range is a consequence of the relatively simple Fe-Ni-Cr ternary composition without the complex carbide or intermetallic phases that broaden the melting range of more heavily alloyed grades.
Q5: What is the tensile strength of Incoloy 800?
In the solution-annealed condition, minimum tensile strength is ≥ 520 MPa (≥ 75 ksi) per ASTM B408. Typical values from production heats range 540–600 MPa. At 700°C, tensile strength is approximately 240 MPa — adequate for self-supporting furnace tube applications but significantly below nickel-base alloys at equivalent temperature.
Q6: What is the yield strength of Incoloy 800?
Minimum 0.2% offset yield strength is ≥ 205 MPa (≥ 30 ksi) at room temperature in the annealed condition. This is comparable to 304 stainless steel (≥205 MPa) but lower than Inconel 600 (≥240 MPa). The yield-to-tensile ratio is approximately 0.35–0.40, typical of annealed austenitic alloys.
Q7: What is the elongation of Incoloy 800?
Minimum elongation (A5) is ≥ 30% in the annealed condition, with typical values of 35–45%. Elongation increases with temperature to >50% at 815°C, providing excellent hot ductility for tube bending, expanding, and flaring operations. Minimum bend radius: approximately 2× tube OD for cold bending, 1.5× OD for hot bending.
Q8: What are the full mechanical properties of Incoloy 800?
Solution-annealed (980–1065°C): tensile ≥520 MPa, yield ≥205 MPa, elongation ≥30%, hardness 75–90 HRB. At 700°C: tensile ~240 MPa, yield ~110 MPa, elongation ~40%. At 815°C: tensile ~140 MPa, yield ~80 MPa, elongation ~55%. These are solid-solution properties with no precipitation hardening contribution — strength at temperature depends entirely on the nickel-chromium-iron matrix.
Q9: What heat treatment does Incoloy 800 require?
Solution annealing at 980–1065°C (1800–1950°F) followed by air cooling or water quenching. Stress relief at 540–650°C for 1–2 hours if required after cold forming. No precipitation hardening is available — Incoloy 800 is solid-solution strengthened only. This is a deliberate metallurgical design that avoids the aging-schedule complexity of precipitation-hardening grades (A-286, Inconel 718).
Q10: What is the annealing temperature for Incoloy 800?
980–1065°C (1800–1950°F) for standard Incoloy 800. This is approximately 100°C lower than the mandatory anneal temperature for Incoloy 800H/800HT (which require ≥1100°C for ASME pressure vessel service above 593°C). The lower temperature preserves a finer grain size for improved room-temperature tensile properties at the cost of reduced creep resistance at elevated temperature — the trade-off that defines 800 vs. 800H.
Q11: How does Incoloy 800 compare to Incoloy 800H and 800HT?
| Property | Incoloy 800 | Incoloy 800H | Incoloy 800HT |
|---|---|---|---|
| Carbon Content | ≤0.10% | 0.05–0.10% | 0.06–0.10% |
| Al+Ti Control | No specification | No specification | 0.85–1.20% combined |
| Solution Anneal | 980–1065°C | ≥1100°C (mandatory) | ≥1100°C (mandatory) |
| Grain Size (Annealed) | Not specified | ASTM 5 or coarser | ASTM 5 or finer |
| ASME Boiler Code Rating | Below 593°C | Above 593°C (Section VIII Div.1) | Best creep rupture properties |
| 100,000 h Creep at 700°C | ~20 MPa | ~30 MPa | ~45 MPa |
| Cost | Baseline | +5–10% | +10–15% |
Selection rule: For general oxidation/corrosion applications, standard Incoloy 800 is sufficient. For ASME-coded pressure vessels operating above 593°C, use Incoloy 800H. For maximum creep rupture life in the 650–815°C range (long-duration furnace tubes), use Incoloy 800HT.
Q12: What is the price of Incoloy 800 per kg?
Indicative EXW pricing for Incoloy 800 round bars is \$15–28/kg, with seamless tubes 20–35% higher and plates 5–15% lower. This positions Incoloy 800 as the most economical of the high-temperature nickel-bearing alloys — approximately 1.5–2× the cost of 316L stainless but roughly 40–50% less than Inconel 600, reflecting the halved nickel content (32% vs. 72%). Shanghai Hangbo Alloy Group returns firm quotations within 2 business hours — email sales@hangboalloy.com.
Q13: Is Incoloy 800 weldable?
Yes, by GTAW, GMAW, SMAW, and SAW. Recommended filler metal: ERNiCr-3 (Inconel 82 / AWS A5.14) for matching corrosion resistance, or ERNiCrFe-2 for matching thermal expansion. For dissimilar welding of Incoloy 800 to carbon steel or stainless, ERNiCr-3 is the standard choice. Preheat is not required; interpass temperature ≤175°C; heat input 1.0–2.5 kJ/mm. Post-weld heat treatment (980–1065°C solution anneal) is recommended for service above 540°C to relieve residual welding stresses and prevent stress-assisted sensitization.
Q14: What product forms does Shanghai Hangbo supply for Incoloy 800?
We supply Incoloy 800 in round bars (Ø6–300 mm, hot-rolled or forged, solution-annealed), seamless tubes (OD 6–219 mm, wall 1–30 mm, per ASTM B163 — the dominant product form for heat exchanger and furnace applications), seamless pipes (OD up to 610 mm, per ASTM B407), plates (3–100 mm, per ASTM B409), forgings (discs, rings, tubesheets per ASTM B564), and welded pipes (OD up to 1219 mm). Available in annealed-and-pickled or bright-annealed finish.
Q15: Does Shanghai Hangbo ship Incoloy 800 internationally?
Yes. We export Incoloy 800 to over 40 countries with terms FOB Shanghai, CIF, CFR, and DAP. Standard destinations include USA, Germany, UK, Italy, UAE, Saudi Arabia, Singapore, South Korea, and India. Stock items (bars, standard-size tubes) ship within 2–4 weeks; mill-order production is 8–12 weeks. All export shipments include full documentation: commercial invoice, packing list, certificate of origin, and EN 10204 3.1 MTC.
Q16: Why does Incoloy 800 resist chloride SCC when 304/316 stainless does not?
Chloride stress-corrosion cracking (Cl-SCC) in austenitic stainless steels has a well-established nickel-content threshold: alloys with less than ~8% nickel (304) or ~12% nickel (316L) are highly susceptible; resistance begins to appear at ~20% Ni; and practical immunity is achieved above ~30% Ni. Incoloy 800, with 30–35% nickel, falls decisively into the immune regime — its FCC nickel-rich matrix resists the localized anodic dissolution at slip steps that initiates SCC cracks. The mechanism is fundamentally compositional, not microstructural: it is the nickel content of the matrix that controls SCC susceptibility, not the grain size or carbide distribution. This is why Incoloy 800 steam generator tubing accumulates 40+ years of nuclear service without a single primary-water SCC failure attributable to the alloy itself.
Contact Shanghai Hangbo Alloy Group
| Channel | Details |
|---|---|
| Company | Shanghai Hangbo Alloy Group Co., Ltd. (宝昭实业（上海）有限公司) |
| Website | www.nickel-alloy.com |
| Email (Sales) | sales@hangboalloy.com |
| Email (Technical) | hangbo@nickel-alloy.com |
| +86 13611656360 | |
| Skype | live:specialalloy001 |
| Address | Room 1508, No. 288 Shiyi Road, Baoshan District, Shanghai 200940, China |
| ISO Certification | ISO 9001:2015 — View certificate on request |
| Response Time | ≤ 10 minutes during business hours (Mon–Fri, 08:00–18:00 GMT+8) |
