NAS 800T； High Nickel Heat Resistant Steel
Characteristics of NAS 800T
A high nickel-content heat-resistant steel, NAS 800T (NCF 800T (UNS N08811), comparable to Alloy 800T, maintain structural stability and provides superior strength, corrosion resistance and oxidation resistance at high temperatures. Using high-temperature heat treatment, the crystal grains as well as the carbon, titanium and aluminum content can be controlled for high creep strength.
Chemical Composition
(%)
| - | C | Si | Mn | P | S | Ni | Cr | Cu | Al | Ti | Al＋Ti | Fe |
| Example | 0.08 | 0.3 | 0.9 | 0.017 | 0.001 | 30.5 | 20.0 | 0.04 | 0.51 | 0.50 | 1.01 | 46.9 |
Corresponding Standard
ASTM B409 / UNS N08800 , UNS N08810 , UNS N08811
ASME SB409 / UNS N08800 , UNS N08810 , UNS N08811
SAE AMS 5871
JIS G4902 / NCF800 , 800H
Mechanical Properties
| - | - | 0.2% Proof stress （N/mm2） |
Tensile strength （N/mm2） |
Elongation （％） |
Grain size （G.S.N.） |
| Example | Hot rolled plate (12mm thick) | 304 | 566 | 40.4 | 3.5 |
| Hot rolled sheet (2mm thick) | 220 | 552 | 48.9 | 3.5 |
Heat Treatment
NAS 800T exhibits an austenite structure similar to austenitic stainless steels, and the heat treatment is similar. Typical heat treatments are as follows:
･ Annealing 980-1100℃ followed by Rapid cooling
･ Stress relief annealing 780-870℃ followed by Air cooling
When creep rupture strength is needed in a high-temperature environment, the following ASTM B409/ASME SB409 heat treatment may be applied:
･ Solution treatment temperature between at least 1150℃ followed by rapid cooling.
This heat treatment for NAS 800T is only applied up to 2 mm thick
High Temperature Properties
High temperature short term tensile strength
| Temperature (℃) |
Annealed | Solution heat treated | ||||
| 0.2% Proof stress (N/mm2) |
Tensile strength (N/mm2) |
Elongation (％) |
0.2% Proof stress (N/mm2) |
Tensile strength (N/mm2) |
Elongation (％) |
|
| 30 | 294 | 597 | 44 | 194 | 525 | 52 |
| 204 | 247 | 532 | 39 | 144 | 450 | 50 |
| 427 | 229 | 514 | 40 | 125 | 453 | 53 |
| 538 | 218 | 495 | 39 | 114 | 427 | 51 |
| 649 | 200 | 372 | 56 | 102 | 383 | 50 |
| 760 | 156 | 221 | 85 | 106 | 223 | 78 |
| 816 | 98 | 171 | 91 | 107 | 174 | 96 |
Creep rupture strength (for hot rolled plate)
| Heat treatment | Test temperature (℃) |
Creep rupture strength (N/mm2) |
||
| 100hr | 1,000hr | 10,000hr | ||
| Annealed 980℃ |
650 | 214 | 158 | 103 |
| 704 | 121 | 73 | 38 | |
| 760 | 81 | 43 | 23 | |
| 816 | 56 | 30 | 17 | Solution heat treated 1150℃ |
650 | 228 | 169 | 110 |
| 704 | 162 | 110 | 73 | |
| 760 | 99 | 66 | 45 | |
| 816 | 64 | 42 | 25 | |
