Alloy 800HT (UNS N08811) - Premium high-temperature nickel alloy with enhanced creep rupture strength. Ideal for chemical processing, petrochemical & industrial furnace applications. ZYTC supplies 800HT in bars, plates, tubes & welding wire. Get technical data & quote.
Delivery :
FOB
minimum order :
50 kilograms
Supply Ability :
5000kilograms / Month
Stock Time :
7-10Day
Country of Origin :
CHINA
Quantity :
add to cart
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Alloy 800HT (UNS N08811) represents the most advanced grade in the 800 series, featuring tightly controlled chemistry optimized for maximum creep-rupture strength. With restricted carbon, aluminum, and titanium ranges, this alloy delivers superior performance in applications requiring long-term structural integrity at temperatures exceeding 1000°F.
1. Product Specifications & Physical Data
ZYTC Alloy supplies UNS N08811 with full certification and traceability for critical high-temperature applications across petrochemical, power generation, and industrial heating sectors.
Available Forms: Round bar, flat bar, rod, plate, sheet, strip, seamless/welded tube, forging stock, custom shapes, and welding wire.
Chemical Composition (Weight %)
Alloy 800HT Specification
Nickel (Ni)
30 - 35
Chromium (Cr)
19 - 23
Iron (Fe)
39.5 minimum
Carbon (C)
0.060 - 0.10
Titanium (Ti)
0.15 - 0.60
Aluminum (Al)
0.15 - 0.60
Manganese (Mn)
≤ 1.50
Silicon (Si)
≤ 1.0
Copper (Cu)
≤ 0.75
Sulfur (S)
≤ 0.015
Physical Properties
Metric
Imperial
Density
7.94 g/cm³
0.287 lb/in³
Melting Range
1357-1385°C
2475-2525°F
Mechanical Properties (Annealed)
Metric
Imperial
Tensile Strength
560 MPa
81,200 psi
Yield Strength
250 MPa
36,300 psi
Elongation at Break
45%
45%
2. Operating Conditions & Selection Criteria
Alloy 800HT (UNS N08811) is specified when standard 800 or 800H grades cannot provide sufficient creep life for pressurized components under continuous high-temperature loading. The precise control of carbon, aluminum, and titanium ensures optimal precipitation characteristics for enhanced rupture strength.
Service Temperature Range: Optimized for continuous operation between 593°C and 980°C (1100°F to 1800°F).
Creep-Rupture Strength: Significantly exceeds standard 800 and 800H due to controlled Al+Ti (0.85-1.20%) and carbon restrictions. Suitable for ASME Section VIII Division 1 applications up to 980°C.
Environmental Resistance: Excellent resistance to oxidation, carburization, and sulfidation. Forms stable, adherent oxide scale that resists spalling under thermal cycling.
Structural Stability: Austenitic structure remains stable during prolonged exposure; immune to sigma phase embrittlement.
3. Fabrication & Material Comparison
While fabricability resembles other 800 series alloys, 800HT requires attention to annealing practices to maintain the grain structure necessary for optimal creep performance.
Machining: Standard iron-based superalloy practices apply. Water-based coolants recommended for high-speed operations; heavy lubricants for drilling and tapping. Carbide tooling preferred for production runs.
Welding: Excellent weldability using GTAW, SMAW, GMAW, and submerged-arc processes. Matching filler metals (ERNiCr-3 or similar) recommended. Pre-weld cleaning essential; post-weld heat treatment typically not required.
Forming & Heat Treatment:
Hot Working Range: 872-1205°C (1600-2200°F)
Forging Range: 1010-1205°C (1850-2200°F)
Annealing: 1149°C (2100°F) followed by air cooling
Cold Working: Responds to conventional methods; hardness increases with cold reduction
Material Comparison:
vs. Alloy 800H: Higher creep-rupture strength through tighter Al+Ti control; preferred for longest design life applications.
vs. 310 Stainless: Superior high-temperature stability; lower thermal expansion; better resistance to thermal fatigue.
vs. RA330: Comparable performance; 800HT offers better code recognition for pressure vessel applications.
Applications
Ethylene pyrolysis tubing and quench systems
High-temperature process piping and manifolds
Industrial furnace components and radiant tubes
Heat treating fixtures and baskets
Chemical and petrochemical reactor internals
Power generation superheater components
Pressure vessels for elevated temperature service
Contact ZYTC Alloy for certified alloy 800HT materials with complete traceability, technical datasheets, ASME/ASTM certification, and competitive pricing on standard sizes or custom-fabricated components.
