Incoloy 800H/HT

General Description

Incoloy 800H is similar to alloy 800 but with improved creep and stress-rupture properties for applications above 650 °C (1200 °F). Resistant to high-temperature oxidation, carburization, and nitridation, it is widely used in petrochemical and thermal processing.

Incoloy 800HT is similar to alloy 800H but with even more precisely controlled composition.

Alloys 800H and 800HT are the standard materials for intermediate temperatures (620–925 °C, or 1150–1700 °F). These alloys combine corrosion resistance with strength and metallurgical stability. Major applications include hydrogen reformer manifolds and pigtail piping, ethylene dichloride furnace tubing, transfer piping, and high-temperature pressure vessels.

Chemical Composition

Grade Ni% Cr% Fe% C% Mn% S% Si% Cu% Al% Ti% Al+Ti%
Incoloy 800H 30.5-35.0 19.0-23.0 Bal. 0.05-0.10 Max 1.50 Max 0.015 Max 1.0 Max 0.75 0.15-0.60 0.15-0.60 0.30-1.20
Incoloy 800HT 30.0-35.0 19.0-23.0 Bal. 0.06-0.10 Max 1.50 Max 0.015 Max 1.0 Max 0.75 0.25-0.60 0.25-0.60 0.85-1.20

Designations

Incoloy 800H

UNS N08810

Werkstoff Nr. 1.4958


Incoloy 800HT

UNS N08811

Werkstoff Nr. 1.4959

Specifications

Incoloy 800H/HT Wire: ISO 9724

Incoloy 800H/HT Bar: ASTM B408

Incoloy 800H/HT Forging: ASTM B564

Incoloy 800H/HT Pipe/Tube: ASTM B163/B407/B755/B751

Incoloy 800H/HT Sheet/Strip: ASTM A240/A480/B409/B609

Physical Properties

Density:8.0 g/cm3

Melting Point: 1370°C-1400 °C

Mechanical Properties

Tensile: Min 450 MPa

Yiled: Min 170 MPa

Elongation: Min 35%

Welding of Incoloy 800H/HT

Alloy 800H and 800HT have the same good weldability as alloy 800. Both are normally used for applications requiring high creep-rupture strength and should be joined with welding products that have suitable strength characteristics for the intended service temperatures.

Filler Metal 82 is used for gas-shielded welding. Filler Metal 82 is also used with Submerged Arc Flux for submerged-arc welding of Incoloy 800H and 800HT.

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