Alloy 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/HT and the addition of up to 1.20 percent aluminium and titanium in alloy 800HT. 800 was the first of these alloys and it was slightly modified into 800H. This modification was to control carbon (.05-.10%) and grain size to optimize stress rupture properties.
In heat treatment applications 800HT has further modifications to the combined titanium and aluminium levels (.85 - 1.20%) to ensure optimum high temperature properties. Alloy 800H/HT was intended for high temperature structural applications. The nickel content makes the alloys highly resistant to both carborisation and to embrittlement from precipitation of sigma phase.
Available tube product forms
Typical Applications
- Chemical & petrochemical processing equipment
-
Power generation
-
Thermal processing fixtures
Typical Manufacturing Specifications
- ASTM B163
-
ASTM B407
-
ASTM B515
-
Also individual customer specifications.
Industries predominantly using this grade
Technical Data
Mechanical Properties
|
Temper |
800 |
800H/HT |
|
Tensile Rm |
77.8 |
ksi (min) |
65 |
ksi (min) |
|
Tensile Rm |
536 |
MPa (min) |
448 |
MPa (min) |
|
R.p. 0.2% Yield |
22 |
ksi (min) |
25 |
ksi (min) |
|
R.p. 0.2% Yield |
150 |
MPa (min) |
172 |
MPa (min) |
|
Elongation (2” or 4D gl) |
20 |
% (min) |
20 |
% (min) |
Physical Properties (Room Temperature)
|
Specific Heat (0-100°C) |
460 |
J.kg-1.°K-1 |
|
Thermal Conductivity |
11.5 |
W.m -1.°K-1 |
|
Thermal Expansion |
14.4 |
μm/μm/°C |
|
Modulus Elasticity |
208 |
GPa |
|
Electrical Resistivity |
9.89 |
μohm/cm |
|
Density |
7.94 |
g/cm3 |
Chemical Composition (% by weight)
|
|
800 |
800H/HT |
|
Element |
Min |
Max |
Min |
Max |
|
Ni |
30 |
35 |
30 |
35 |
|
Fe |
- |
39.5 |
- |
39.5 |
|
Cr |
19 |
23 |
19 |
23 |
|
Cu |
- |
0.75 |
- |
0.75 |
|
Ti |
0.15 |
0.6 |
0.25 |
0.6 |
|
Al |
0.15 |
0.6 |
0.25 |
0.6 |
|
C |
- |
0.1 |
0.06 |
0.1 |
|
Mn |
- |
1.5 |
- |
1.5 |
|
S |
- |
0.015 |
- |
0.015 |
|
Si |
- |
1.0 |
- |
1.0 |