INCOLOY 800H/800HT
 
 

Other common names: Alloy 800, Alloy 800H/HT
Incoloy 800, 800H, and 800HT are nickel-iron-chromium alloys with good strength and excellent resistance to oxidation and carburization in high-temperature exposure. These nickel steel alloys are identical except for the higher level of carbon in alloy 800H, and the addition of up to 1.20 percent aluminum and titanium in alloy 800HT. Incoloy 800 was the first of these alloys and it was slightly modified into Incoloy 800H. This modification was to control carbon (.05-.10%) and grain size to optimize stress rupture properties. Incoloy 800HT has further modifications to the combined titanium and aluminum levels (.85-1.20%) to ensure optimum high temperature properties.The nickel alloy is dual certified (800H/HT) and combines the properties of both forms. Incoloy 800H/HT alloy was intended for high temperature structural applications. The nickel content makes the alloys highly resistant to both chloride stress-corrosion cracking and to embrittlement from precipitation of sigma phase. The general corrosion resistance is excellent. In the solution annealed condition, alloys 800H and 800HT have superior creep and stress rupture properties.

 

In what applications is Incoloy 800H/HT used?

    • Heat-treating equipment
    • Hydrocarbon cracking
    • Valves, fittings and other components exposed to corrosive attack from 1100-1800° F
    • Industrial furnaces
    • Chemical and petrochemical processing
    • Super-heater and re-heaters in power plants
    • Pressure vessels
    • Heat exchangers
 
 

Alloy 800 (UNS N08800) Chemical Composition, %

 

Ni

Fe

Cr

Cu

Ti

Al

C

Mn

S

Si

30.0-35.0

39.5 min

19.0-23.0

.75 max

.15-.60

.15-.60

.1 max

1.5 max

.015 max

1.0 max

 

Alloy 800H (UNS N08810) Chemical Composition, %

 

Ni

Fe

Cr

Cu

Ti

Al

C

Mn

S

Si

30.0-35.0

39.5 min

19.0-23.0

.75 max

.15-.60

.15-.60

.05-.10 max

1.5 max

.015 max

1.0 max

 
Alloy 800HT (UNS N08811) Chemical Composition, %
 

Ni

Fe

Cr

Cu

Ti

Al

C

Mn

S

Si

30.0-35.0

39.5 min

19.0-23.0

.75 max

.25-.60

.85-1.20

.06-.10 max

1.5 max

.015 max

1.0 max