Material Family

Nickel-Iron-Chromium Austenitic Alloy (Solid-Solution Strengthened)

An economical bar stock for high-temperature service, with lower nickel content than Inconel grades.

Common Forms (Bar)

Hot Rolled, Forged, or Cold Finished Rounds, Hexagons, Squares. Also as Forging Billet.

Available in a wide range of diameters; forging billet is used for critical high-temperature parts.

Chemical Composition (Typical wt.%)

Ni: 30.0 - 35.0
Cr: 19.0 - 23.0
Fe: ≥ 39.5 (Balance)
Al: 0.15 - 0.60
Ti: 0.15 - 0.60
C:
• 800: ≤ 0.10
• 800H: 0.05 - 0.10
• 800HT: 0.06 - 0.10 (plus Al+Ti: 0.85-1.20)

High Iron (Fe) content makes it more economical. Controlled C, Al, Ti in H/HT grades are critical for high-temperature strength.

Mechanical Properties (Annealed, Room Temp)

Tensile Strength (Rm): 520 - 690 MPa
Yield Strength (Rp0.2): 205 - 345 MPa
Elongation (A): 30 - 45%

Good ductility and moderate strength. The key advantage is strength retention at high temperatures.

Physical Properties

Density: 7.94 g/cm³
Melting Range: 1350 - 1400 °C
Recommended Service Temp: Up to ~700°C for general corrosion; H/HT grades are designed for long-term service above 540°C (1000°F).

Distinction: Standard 800 bar is for general use; 800H/HT bar is for high-temperature, high-strength applications.

Key Performance Attributes

• Excellent resistance to oxidation, carburization, and sulfidation.

• Good resistance to chloride stress corrosion cracking and aqueous corrosion.

• Good strength and workability.

• 800H/HT: Superior and predictable creep rupture strength at high temperatures.

An excellent all-rounder bar for petrochemical and power industry components.

Key Standards (Bar)

ASTM B408 / ASME SB-408 (Standard Specification for Nickel-Iron-Chromium Alloy Rod and Bar), ASTM B407 (Mandatory for 800H/HT grain size control)

For 800H/HT, compliance with ASTM B407 (coarse grain anneal) is essential to guarantee high-temperature properties.

Mandatory Heat Treatment (for 800H/HT Bar)

Bar must be annealed at a minimum of 1121°C (2050°F) to achieve an ASTM grain size of 5 or coarser.

This controlled coarse grain structure is mandatory to develop the specified enhanced creep rupture strength in the final component.

Machinability

Machinability Rating: ~40% (better than many nickel alloys due to its iron content). It is gummy and work-hardens; requires sharp tools, positive rakes, and moderate feeds and speeds.

More machinable than Inconel alloys, but still requires proper technique.

Typical Bar Applications

• Heat Treating Fixtures: Baskets, trays, grids, pins, rollers for furnaces.
• Power Generation: Turbine blades, bolts, fasteners, valve parts for high-temperature service.
• Petrochemical: Hangers, clips, reformer tube supports, pigtails (800H/HT).
• General: Fasteners, shafts, and machined parts for corrosive high-temperature environments.

The most common bar stock for high-temperature fixtures and components in the heat treating and power industries.