Alloy 800H (UNS N08810) is a controlled-carbon version of standard Alloy 800, specifically developed for prolonged high-temperature service. The tighter carbon range (0.05-0.10%) combined with controlled grain size delivers enhanced creep resistance and stress-rupture strength, making this material the preferred choice for pressure vessels and furnace components operating above 1000°F.

1. Product Specifications & Physical Data

ZYTC Alloy supplies UNS N08810 in all standard mill forms with full traceability and certification to ASME/ASTM requirements.

• Available Forms: Round bar, flat bar, rod, plate, sheet, strip, seamless/welded tube, forging stock, welding wire, and custom shapes.

Alloy 800H (UNS N08810) is specified when standard stainless steels or even Alloy 800 cannot meet the creep-life requirements for pressurized components at elevated temperatures. The controlled chemistry and grain structure provide predictable long-term performance.

• Service Temperature Range: Optimized for continuous operation from 592°C to 980°C (1100°F to 1800°F).

• Creep Resistance: The controlled carbon content (0.05-0.10%) combined with aluminum and titanium additions provides superior stress-rupture properties compared to standard Alloy 800.

• Environmental Resistance: Forms a stable oxide layer that resists oxidation, carburization, and sulfidation in petrochemical and heat-treating atmospheres.

• Microstructural Stability: Maintains austenitic structure without sigma phase embrittlement during prolonged thermal exposure.

3. Fabrication & Material Comparison

While similar to Alloy 800 in basic chemistry, 800H requires specific attention to heat treatment and hot working practices to achieve the desired grain structure for creep performance.

• Machining: Work-hardens during cutting operations. Carbide tooling recommended for continuous turning. Use water-based coolants for high-speed operations; heavy lubricants for drilling and tapping.

• Welding: Excellent weldability using GTAW, SMAW, GMAW, and submerged-arc processes. Matching filler metals (ERNiCr-3 or similar) should be used to maintain properties in the weld zone. Post-weld heat treatment not typically required.

• Forming & Heat Treatment:

  • Hot Working Range: 871-1204°C (1600-2200°F)

  • Annealing: 1177°C (2150°F) followed by air cooling

  • Cold Working: Responds to standard methods; use soft tooling materials to minimize galling

• Material Comparison:

  • vs. Alloy 800: Higher creep strength due to controlled carbon and grain size; preferred for ASME Section VIII pressure vessel applications.

  • vs. 310 Stainless: Better high-temperature stability and resistance to thermal fatigue; lower thermal expansion.

  • vs. Alloy 600: Comparable performance at lower cost; better resistance to sulfur-containing environments.

Applications

• Ethylene furnace quench boilers and cracking tubes

• High-temperature valves, fittings, and piping systems

• Industrial furnace components and heat-treating fixtures

• Chemical processing equipment

• Power generation superheaters and reheaters

• Pressure vessels for high-temperature service

Contact ZYTC Alloy for certified alloy 800H materials with complete traceability, technical datasheets, and competitive pricing on standard sizes or custom-fabricated components.

Email:daisy@zytcsteel.com

WhatsApp/WeChat: +86 17335753350