Super Alloy Incoloy 800HT™ (UNS N08811)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
     Machinability
     Forming
     Welding
     Heat Treatment
     Forging
     Hot Working
     Cold Working
     Annealing
     Hardening
Applications

Introduction

Super alloys are also referred to as high performance alloys. They have good creep and oxidation resistance, and are utilized where high surface stability is required. They also have an ability to function under high temperatures and mechanical stress. They can be strengthened by solid-solution hardening, work hardening, and precipitation hardening. They are divided into three groups such as iron-based, nickel-based, and cobalt-based alloys.

Incoloy 800HT™ is a nickel-iron-chromium alloy, and also a modified version of alloy 800. It has high creep-rupture strength. The following datasheet gives an overview of Incoloy 800HT™.

Chemical Composition

The chemical composition of Incoloy 800HT™ is outlined in the following table.

Elements Content (%)
Iron, Fe ≥ 39.5
Nickel, Ni 30- 35
Chromium, Cr 19-23
Manganese, Mn ≤ 1.50
Silicon, Si ≤ 1
Copper, Cu ≤ 0.75
Titanium, Ti 0.15-0.60
Aluminum, Al 0.15-0.60
Carbon, C 0.060-0.10
Sulfur, S ≤ 0.015

Physical Properties

The physical properties of Incoloy 800HT™ is displayed in the following table.

Properties Metric Imperial
Density 7.94 g/cm³ 0.287 lb/in³
Melting point 1357-1385 °C 2475-2525 °F

Mechanical Properties

The following table shows the mechanical properties of Incoloy 800HT™.

Properties Metric Imperial
Tensile strength (annealed) 560 MPa 81200 psi
Yield strength (annealed) 250 MPa 36300 psi
Elongation at break (annealed prior to test) 45% 45%

Thermal Properties

The thermal properties of Incoloy 800HT™ are given in the following table.

Properties Metric Imperial
Thermal expansion co-efficient (@ 20-100°C/68-212°F) 14.4 µm/m°C 8.00 µin/in°F
Thermal conductivity 11.5 W/mK 79.8 BTU in/hr. ft².°F

Other Designations

Other designations that are equivalent to Incoloy 800HT™ include:

  • ASTM B407
  • ASTM B408
  • ASTM B409
  • DIN 1.4876
  • DIN 1.4959

Fabrication and Heat Treatment

Machinability

Incoloy 800HT™ can be machined using conventional machining methods which are used for iron based alloys. Machining operations are performed using machining coolants. High-speed operations such as grinding, turning, or milling, are performed using water-base coolants. Drilling, broaching, tapping, or boring can be performed using heavy lubricants.

Forming

Incoloy 800HT™ can be formed using all conventional techniques.

Welding

Incoloy 800HT™ is welded using shielded metal-arc welding, gas-tungsten arc welding, gas metal-arc welding, and submerged-arc welding methods.

Heat Treatment

Incoloy 800HT™ can be heat treated by annealing. However, it does not harden by heat treatment.

Forging

Incoloy 800HT™ is forged at 1010 to 1205°C (1850 to 2200°F).

Hot Working

Incoloy 800HT™ is hot worked at 872 to 1205°C (1600 to 2200°F).

Cold Working

Incoloy 800HT™ can be cold worked using standard tooling.

Annealing

Incoloy 800HT™ is annealed at 1149°C (2100°F) followed by cooling.

Hardening

Incoloy 800HT™ is hardened by cold working only.

Applications

Incoloy 800HT™ is used in petrochemical equipments for heat exchangers.

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