Alloy 800

Titanium

Nickel

Overview

Grades & Materials

Pure Nickel

Nickel–Chromium Alloys

Nickel–Molybdenum Alloys

Nickel–Chromium–Molybdenum Alloys

Nickel–Iron Alloys

Alloy 800

Alloy 800H

Alloy 800HT

Applications

Products

Standards & Quality

Technical Knowledge

Selection Guide

Stainless

Carbon

Alloy

Copper, Brass and Bronze

Alloy 800

Alloy 800 is a nickel–iron–chromium (Ni–Fe–Cr) alloy developed for structural stability and strength at elevated temperatures, combined with good resistance to oxidation and carburization.
It is widely used in heat exchangers, pressure equipment, and high-temperature industrial systems where thermal stability and long-term reliability are more critical than extreme corrosion resistance.

Within the Nickel–Iron alloy family, Alloy 800 is considered the base grade, providing a balanced combination of strength, fabricability, and thermal performance.

Chemical & Metallurgical Characteristics

Alloy 800 is based on a controlled Ni–Fe–Cr austenitic structure, designed to remain stable under prolonged thermal exposure.

Key Metallurgical Features

  • Nickel content stabilizes the austenitic structure

  • Iron provides structural strength and cost efficiency

  • Chromium improves oxidation and carburization resistance

  • Stable FCC microstructure

  • Good resistance to grain growth under normal service conditions

This metallurgical balance ensures predictable behavior during long-term high-temperature service.

High-Temperature & Oxidation Performance

Alloy 800 is designed for moderate to high-temperature applications.

Excellent Performance In:

  • Oxidizing atmospheres at elevated temperatures

  • Carburizing environments

  • Steam and hydrocarbon processing

  • Long-term thermal exposure without loss of ductility

Limitations:

  • Not intended for strong acidic environments

  • Limited resistance to severe chloride corrosion

  • Lower creep strength than Alloy 800H / 800HT

Alloy 800 should be selected where thermal stability and oxidation resistance are required, but extreme high-temperature strength is not critical.

Mechanical Properties (Typical)

Alloy 800 provides:

  • Moderate tensile and yield strength

  • Good ductility and toughness

  • Stable mechanical behavior during thermal cycling

It is suitable for pressure-containing components operating at elevated temperatures within standard design limits.

Typical Applications

Alloy 800 is widely used in thermal and structural service environments.

Common Applications Include:

  • Heat exchanger and condenser tubing

  • Pressure vessels and piping systems

  • Industrial furnaces and heaters

  • Petrochemical and refining equipment

  • Steam generation and power systems

It is often specified when carbon steels or stainless steels lack adequate high-temperature stability.

Product Forms Available

Alloy 800 is commonly supplied in:

  • Seamless tubes

  • Pipes

  • Plates and sheets

  • Bars and rods

  • Forgings and tube sheets

For heat exchangers and pressure equipment, seamless Alloy 800 tubes are frequently selected due to:

  • Uniform wall thickness

  • Reliable pressure performance

  • Stable thermal behavior

Manufacturing & Fabrication

Alloy 800 offers good fabrication characteristics:

  • Hot and cold working

  • Solution annealing

  • Conventional welding procedures

The alloy is known for good weldability and formability, making it suitable for complex industrial assemblies.

Standards & Specifications

Alloy 800 products are commonly manufactured in accordance with:

  • ASTM material standards

  • ASME pressure equipment codes

  • Project-specific technical specifications

Typical Inspection & Testing:

  • Chemical composition analysis

  • Mechanical testing

  • Dimensional inspection

  • Eddy current or ultrasonic testing (for tubes)

  • PMI verification

Full Mill Test Certificates (MTC) and traceability are typically provided.

Alloy 800 vs Alloy 800H / 800HT (Concept)

  • Alloy 800

    • Base grade with balanced properties

    • Suitable for general high-temperature service

  • Alloy 800H

    • Higher carbon content

    • Improved creep and rupture strength

  • Alloy 800HT

    • Controlled grain size and chemistry

    • Superior performance in extreme high-temperature service

Selection depends on operating temperature, pressure, and creep requirements.

When to Choose Alloy 800

Alloy 800 is recommended when:

  • Operating temperatures are elevated but controlled

  • Thermal stability is more critical than corrosion resistance

  • Good fabricability and weldability are required

  • Cost-effective high-temperature performance is desired

It may be upgraded to 800H or 800HT when:

  • Higher creep strength is required

  • Service temperatures increase significantly

Summary

Alloy 800 is positioned within Nickel → Grades & Materials → Nickel–Iron Alloys and is selected for applications requiring thermal stability and structural reliability at elevated temperatures.

Explore next:

  • Grades: Alloy 800H · Alloy 800HT

  • Applications: Heat Exchangers · Power Generation

  • Guide: Nickel Selection Guide