Alloy 801 (UNS N08801)  is a modified version of Alloy 800 with controlled titanium addition exceeding 1.0%. This stabilization makes the alloy specifically resistant to intergranular stress corrosion cracking in polythionic acid environments, a common concern in petrochemical desulfurization service. The alloy combines high-temperature strength with targeted corrosion resistance for critical processing equipment.

1. Product Specifications & Physical Data

ZYTC Alloy supplies UNS N08801 in mill forms suitable for fabricators serving the petrochemical, aerospace, and energy conversion sectors.

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

• Specifications: AMS 5552, ASTM B163, ASTM B407 .

Note: Composition ranges vary slightly across specifications; values shown represent common industry standards .

*Note: High-strength properties shown are typical for wire in tempered condition; annealed tube properties are lower per ASTM B407 .*

2. Operating Conditions & Selection Criteria

Alloy 801 (UNS N08801)  is specified when standard 800 series alloys risk intergranular attack in sulfur-bearing process environments. The titanium stabilization prevents chromium carbide precipitation at grain boundaries, maintaining corrosion resistance after welding or high-temperature exposure .

• Service Temperature Range: Effective up to 870°C (1600°F) for oxidation resistance; optimized for 600-700°C (1112-1292°F) creep service .

• Polythionic Acid Resistance: Titanium stabilization prevents chromium depletion at grain boundaries, eliminating susceptibility to intergranular stress corrosion cracking in refineries processing sulfur-bearing feedstocks .

• Oxidation Resistance: Forms protective chromium oxide scale; resists scaling in air and combustion atmospheres up to 900°C (1652°F) .

• Creep Strength: Elevated titanium content improves tensile and rupture properties compared to Alloy 800; 100-hour rupture strength at 650°C is 250 MPa .

3. Fabrication & Material Comparison

While similar to Alloy 800 in basic fabricability, the titanium addition requires attention to welding practices to avoid nitride formation or hot cracking.

• Machining: Work-hardens during cutting; machinability rating approximately 50% of B1112 steel. Carbide tooling recommended with positive rake angles. Water-based coolants for high-speed operations; heavy lubricants for drilling and tapping .

• Welding: Good weldability using GTAW, SMAW, GMAW. Matching filler metals (ERNiCr-3 type) recommended. Titanium addition may increase sensitivity to hot cracking; proper pre-weld cleaning and controlled heat input essential .

• Forming & Heat Treatment:

  • Hot Working: 1050-1150°C (1922-2102°F)

  • Annealing: 1093°C (2000°F) followed by rapid cooling

  • Cold Working: Responds to conventional methods; soft tooling recommended to minimize galling .

• Material Comparison:

  • vs. Alloy 800: Higher titanium content (≥1.1% vs. 0.15-0.60%) provides superior resistance to polythionic acid stress corrosion cracking; preferred for hydrodesulfurizer service .

  • vs. 321 Stainless: Higher nickel content (32% vs. 9-12%) offers better resistance to chloride stress corrosion cracking and high-temperature stability.

  • vs. Alloy 825: Lower molybdenum content; more cost-effective where reducing acid resistance not required.

Applications

• Petrochemical hydrodesulfurizer components

• Catalytic reforming units

• High-temperature process piping

• Aerospace rocket motor components

• Nuclear reactor internals

• Gas turbine combustion chambers and transition pieces

• Industrial furnace fixtures

Contact ZYTC Alloy for certified alloy 801 materials with complete traceability, technical datasheets, and competitive pricing on standard sizes or custom-fabricated components.

Email:daisy@zytcsteel.com

WhatsApp/WeChat: +86 17335753350