| HAYNES® 242® alloy exhibits
very good oxidation resistance
at temperatures up to 1500°F
(815°C), and should not require
protective coatings for continuous
or intermittent service at these temperatures. The alloy is
not specifically designed for
use at higher temperatures, but
can tolerate short-term exposures. |
Schematic Representation of Metallographic Technique used for Evaluating Oxidation Tests |
|
Comparative Burner Rig Oxidation-Resistance at 1400°F (760°C) for 500 Hours |
|
Metal
Loss |
Average
Metal
Affected |
Maximum
Metal
Affected |
|
|
| |
|
Alloy |
Mils |
μm |
Mils |
μm |
Mils |
μm |
|
HASTELLOY® N alloy |
0.7 |
18 |
0.8 |
20 |
1.2 |
30 |
242® alloy |
1.1 |
28 |
1.2 |
30 |
1.6 |
41 |
HASTELLOY B alloy |
1.8 |
46 |
2.6 |
66 |
2.8 |
71 |
Alloy 909 |
0.3 |
8 |
10.8 |
275 |
12.8 |
325 |
|
Oxidation Test Parameters
Burner rig oxidation tests were
conducted by exposing samples
3/8 inch x 2.5 inches x thickness
(9mm x 64mm x thickness), in a
rotating holder, to the products of
combustion of No. 2 fuel oil burned at a ratio of air to fuel of
about 50:1. (Gas velocity was
about 0.3 mach). Samples were
automatically removed from the
gas stream every 30 minutes and fan-cooled to near ambient
temperature and then reinserted
into the flame tunnel. |
|
Microstructures shown relate to
the burner rig oxidation test
data shown on the page
opposite for three of the
materials evaluated. The black
area shown at the top of the
pictures for 242® alloy and
alloy B represent thickness loss
during the test. The alloy 909
apparently exhibited only minor
thickness loss. This is believed
to be a consequence of the
sample actually swelling during
the exposure due to oxygen
absorption. The sample also
developed a very thick, coarse
scale and extensive internal
oxidation. There was also
evidence of significant cracking
in the alloy 909 specimen
due to the thermal cycling, even though the test samples
were not constrained. |
|
Comparative Oxidation-Resistance in Flowing Air at 1500°F (815°C) for 1008 Hours* |
| |
Metal Loss |
Average Metal Affected |
| |
|
| Alloy |
Mils |
μm |
Mils |
μm |
|
242® alloy |
0.0 |
0 |
0.5 |
13 |
HASTELLOY® S alloy |
0.0 |
0 |
0.5 |
13 |
HASTELLOY X alloy |
0.1 |
3 |
1.1 |
28 |
HASTELLOY N alloy |
0.4 |
10 |
1.2 |
30 |
| HASTELLOY B alloy |
7.2 |
183 |
8.2 |
208 |
| Alloy 909 |
4.4 |
112 |
19.4 |
493 |
| *Coupons exposed to flowing air at a velocity of 7.0 feet/minute (2.1m/minute) past the samples. Samples cycled to room temperature once-a-day. |
|
| |
