HAYNES® 214® alloy has very good
resistance to carburization, as
measured in both packed graphite
exposure tests and mixed gas
exposure tests. Results for these tests
are presented in the following pages. All results are presented in terms of
the mass of carbon absorption per
unit area, which was obtained from
the equation M = C(W/A) where M =
the mass of carbon absorption per
unit area (mg/cm2). C = difference in carbon (weight fraction) before and
after exposure, W = weight of the
unexposed specimen (mg) and A =
surface area of the specimen exposed
to the test environment (cm2).
|
Packed Carburization Resistance |
| Carbon absorption observed for 214
alloy following 500 hour exposure in
packed graphite at 1800°F (980°C)
was very low, as shown below. While superior resistance was
exhibited by HAYNES HR-120® and 556® alloys, other alloys tested
exhibited significantly greater carbon absorption. In particular, the resistance
to carburization of 214 alloy was far
better than that for the stainless steel
type materials. |
 |
Mixed Gas Carburization Tests |
| Carbon absorption observed for
214 alloy following exposure at both
1700°F (925°C) and 1800°F (980°C)
to a carburizing gas mixture was
significantly lower than that for all other materials tested. This is shown
in the graphs on the following pages.
For these tests, the exposure was
performed in a gas environment
consisting of (by volume %) 5.0% H2, 5.0% CO, 5.0% CH4 and the balance
argon. The calculated equilibrium
composition for the test environments
are shown together with the results on
the following pages. |
Comparative 1700°F (925°C) Mix Gas Carburization Tests |
| The calculated equilibrium
composition (volume %) at 1700°F
(925°C) and one atma was 14.2% H2, 4.74% CO, 0.0044% CO2, 0.032
CH4 and balance Argon. The activity
of Carbon was 1.0 and the partial pressure of Oxygen was 2.47 x 10-22 atma. |
 |
Typical Carburized Microstructures (Unetched) After Exposure
For 215 Hours at 1700°F (925°C)
|
 |
HAYNES® 214® alloy |
Type 310 Stainless Steel |
|
Comparative 1800°F (980°C) Mix Gas Carburization Tests |
| The calculated equilibrium
composition (volume %) at 1800°F (980°C) and one atma was 14.2% H2, 4.75% CO, 0.0021% CO2, 0.024% CH4, 0.0098% H2O and balance argon. The activity of Carbon was 1.0 and the partial pressure of Oxygen
was 6.78 x 10-22 atma. |
Typical Carburized Microstructures (Unetched) After Exposure
For 55 Hours at 1800°F (980°C)
|
 |
HAYNES® 214 ® alloy |
INCONEL alloy 617
Note: Alloy 617 is carburized to the center of the sample. |
|
