COMPREHENSIVE TECHNICAL ANALYSIS AND DATASHEET OF INCOLOY 800H (UNS N08810) FASTENING SYSTEMS
Incoloy 800H (officially designated as UNS N08810) is a controlled-composition derivative of the foundational Alloy 800. While sharing the same base chemistry, Alloy 800H is engineered specifically for high-temperature structural applications where resistance to creep and stress-rupture is the primary design requirement. By strictly controlling the carbon content and utilizing a high-temperature solution annealing process, the alloy achieves a significantly coarser grain structure.
This refined metallurgical state grants Incoloy 800H superior creep-rupture characteristics compared to the standard Grade 800. It is the definitive fastening choice for industrial furnace components, steam generator tubing, and petrochemical process piping operating at temperatures exceeding 1100°F (593°C), where long-term stability under stress is critical to preventing catastrophic system failure.
■ Product Overview & Specifications
Incoloy 800H fasteners are supplied in a specialized solution-annealed condition (minimum 2100°F/1150°C) to ensure the coarse grain size required by ASTM and ASME specifications for high-temperature service.
| Material Classification | High-Carbon, Coarse-Grain Nickel-Iron-Chromium Alloy |
|---|---|
| UNS Designation | N08810 |
| Microstructure | Austenitic (Coarse Grain Size ASTM No. 5 or coarser) |
| Magnetic State | Non-Magnetic |
| Density | ~7.94 g/cm³ (0.287 lb/in³) |
| Melting Range | 2475°F – 2525°F (1357°C – 1385°C) |
| Size Range | Metric: M6 to M100 | Imperial: 1/4" to 4" Specializing in high-temp studs and precision machined bolts. |
| Thread Types | UNC, UNF, 8UN, Metric Coarse, Metric Fine |
■ Proprietary Datasheet Download (GATED)
Access professional-grade technical data for Incoloy 800H, including Larson-Miller Parameter charts for creep-rupture life, comparative stress-rupture curves (800 vs 800H), and high-temp oxidation rate data.
Incoloy 800H (N08810) — Complete Technical Datasheet
Contains detailed ASME Section I and VIII allowable stress tables up to 1500°F, grain size verification logs, and specific high-temperature K-factor installation data.
⬇ DOWNLOAD DATASHEET■ MTC Integration Section
Because the performance of 800H depends on grain size and carbon content, Ananka Group enforces the most stringent metallurgical documentation protocols.
- EN 10204 Type 3.1: Mandatory reporting of Carbon content (0.05 – 0.10%), Grain Size verification (ASTM No. 5 or coarser), and Solution Anneal temperature, alongside mechanical test results.
- EN 10204 Type 3.2: Third-party witness testing facilitated for critical boiler components or refinery process equipment requiring absolute compliance.
■ Chemical Composition (UNS N08810)
The chemical composition of 800H is virtually identical to Alloy 800, but with a strictly enforced Carbon range and the requirement for a high-temperature solution anneal to optimize creep resistance.
| Nickel (Ni) | Chromium (Cr) | Iron (Fe) | Carbon (C) | Aluminum (Al) | Titanium (Ti) | Manganese (Mn) |
|---|---|---|---|---|---|---|
| 30.0 – 35.0 | 19.0 – 23.0 | 39.5 Min | 0.05 – 0.10 | 0.15 – 0.60 | 0.15 – 0.60 | 1.50 Max |
*Total Al + Ti content is controlled to 0.30% – 1.20% to stabilize high-temperature strength.
■ Mechanical Properties & High-Temp Strengths
Alloy 800H is specifically utilized for its strength at temperatures where creep becomes the limiting factor. Below 1100°F, standard Alloy 800 is often sufficient; above this threshold, 800H is mandatory.
| Property | Room Temperature (Annealed) | At 1200°F (650°C) |
|---|---|---|
| Tensile Strength (Min) | 65 ksi (450 MPa) | ~55 ksi (380 MPa) |
| Yield Strength (0.2% Offset, Min) | 25 ksi (170 MPa) | ~20 ksi (138 MPa) |
| Elongation in 2" (Min) | 30% | ~35% |
| 10,000-Hour Rupture Stress | N/A | ~15 ksi (103 MPa) |
■ Equivalent Grades & Designations
| Standard / System | Designation |
|---|---|
| UNS Designation | N08810 |
| Common Trade Name | Incoloy 800H®, Alloy 800H |
| ASTM Fastener Specs | ASTM B408 (Bar), ASTM A240 (Plate/Sheet) |
| European Equivalent | W.Nr. 1.4958 / X5NiCrAlTi31-20 |
■ Applications & Industries
Alloy 800H is the industry standard for high-temperature equipment in the following sectors where creep is a major design factor:
- Chemical & Petrochemical: Hydrocarbon cracking furnace tubes, pigtails, and process bolting for ethylene production.
- Power Generation: Superheater and reheater tubing fasteners and structural hangers in coal and nuclear plants.
- Industrial Furnaces: High-heat radiant tubes, retorts, and muffle fasteners operating continuously above 1100°F.
- Thermal Processing: Heat-treatment fixtures and furnace structural anchors requiring longevity under thermal stress.
■ Compatible Fastener Assemblies
Pairing 800H components with identical metallurgical grades is essential to maintain uniform creep rates across the entire bolted joint assembly.
| External Threads (Incoloy 800H) | Recommended Mating Component (Nuts) |
|---|---|
| Incoloy 800H Stud Bolts | Incoloy 800H Heavy Hex Nuts |
| Incoloy 800H Hex Bolts | Incoloy 800H Standard / Heavy Hex Nuts |
■ Torque & Installation Guidelines
Alloy 800H is subject to thread galling. Furthermore, because these fasteners are removed for maintenance after years of high-heat service, the use of high-purity, metal-free or nickel-based anti-seize is mandatory.
| Nominal Diameter | Threads Per Inch (UNC) | Target Torque — Lubricated (ft-lbs) |
|---|---|---|
| 1/2" | 13 | 35 - 45 |
| 5/8" | 11 | 70 - 90 |
| 3/4" | 10 | 120 - 150 |
| 1" | 8 | 300 - 350 |
■ Why Choose Ananka Group?
Ananka Group manages the sophisticated metallurgical requirements of 800H with absolute precision to ensure safety in high-pressure thermal systems.
- Verified Grain Size: We perform microscopic grain size analysis on all 800H batches to guarantee compliance with ASTM coarse-grain requirements.
- Expert Solution Annealing: High-temperature processing (min 1150°C) is verified to ensure the carbon is in solution and the grain structure is optimized for creep.
- Precision Threading: Advanced machining of nickel alloys ensuring flawless thread profiles and dimensional stability.
- Full Traceability: 100% heat lot tracking, ensuring that your high-temp boiler or furnace system is secured with authentic, certified alloys.
■ Frequently Asked Questions
1. Why is grain size important for Incoloy 800H?
At high temperatures, metals deform primarily through "grain boundary sliding." Coarser (larger) grains have less surface area per unit volume, which significantly reduces the speed of this deformation, thereby increasing the material's creep and rupture strength.
2. Can I use Alloy 800 in place of Alloy 800H?
For service below 1100°F (593°C), yes. However, above this temperature, standard Alloy 800 lacks the grain size and carbon content to resist creep deformation. Using standard 800 in place of 800H in high-heat zones will result in premature fastener elongation and joint failure.
3. Is 800H magnetic at high temperatures?
No. Incoloy 800H remains a non-magnetic austenitic alloy from room temperature all the way through its full high-temperature service range.
4. Does 800H resist carburization?
Yes. The high Nickel and Chromium content provide excellent resistance to both oxidation and carburizing atmospheres, making it the premier choice for internal combustion furnace components and ethylene pigtails.