0
Research Papers: Gas Turbines: Manufacturing, Materials, and Metallurgy

High-Temperature Performance of Cast CF8C-Plus Austenitic Stainless Steel

[+] Author and Article Information
Philip J. Maziasz

Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6156

Bruce A. Pint

Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6156pintba@ornl.gov

J. Eng. Gas Turbines Power 133(9), 092102 (Apr 15, 2011) (5 pages) doi:10.1115/1.4002828 History: Received June 28, 2010; Revised July 19, 2010; Published April 15, 2011; Online April 15, 2011

Covers and casings of small to medium size gas turbines can be made from cast austenitic stainless steels, including grades such as CF8C, CF3M, or CF10M. Oak Ridge National Laboratory and Caterpillar have developed a new cast austenitic stainless steel, CF8C-Plus, which is a fully austenitic stainless steel, based on additions of Mn and N to the standard Nb-stabilized CF8C steel grade. The Mn addition improves castability, as well as increases the alloy solubility for N, and both Mn and N synergistically act to boost mechanical properties. CF8C-Plus steel has outstanding creep-resistance at 600900°C, which compares well with Ni-based superalloys such as alloys X, 625, 617, and 230. CF8C-Plus also has very good fatigue and thermal fatigue resistance. It is used in the as-cast condition, with no additional heat-treatments. While commercial success for CF8C-Plus has been mainly for diesel exhaust components, this steel can also be considered for gas turbine and microturbine casings. The purposes of this paper are to demonstrate some of the mechanical properties, to update the long-term creep-rupture data, and to present new data on the high-temperature oxidation behavior of these materials, particularly in the presence of water vapor.

FIGURES IN THIS ARTICLE
<>
Copyright © 2011 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

The new CRS housing exhaust component using CF8C-Plus cast stainless steel in production since 2007

Grahic Jump Location
Figure 2

Yield and ultimate tensile stress values as a function of temperature for CF8C and CF8C-Plus made by static and centrifugal casting processes

Grahic Jump Location
Figure 3

Yield strength at 700°C and 800°C for several different heat-resistant cast and solid-solution alloys. All data for cast materials, except for wrought alloy X.

Grahic Jump Location
Figure 4

LMP plot of the creep-rupture data for CF8C-Plus compared with CF8C and other exhaust component candidate alloys. CF8C+CuW exhibited even longer rupture times.

Grahic Jump Location
Figure 5

LMP plot of the creep-rupture data for CF8C-Plus compared with several Ni-based alloys

Grahic Jump Location
Figure 6

Number of fatigue cycles to failure as a function of strain range for CF8C and CF8C-Plus at 750°C(R=−1)

Grahic Jump Location
Figure 7

Light microscopy of polished cross sections of specimens after 5 kh at 650°C in laboratory air. (a) CF8C, (b) CF8C-Plus, and (c) CF8C+Cu,W.

Grahic Jump Location
Figure 8

Specimen mass change for various cast stainless steels during 100 h cycles in humid air at 700°C. The mass loss for 347HFG indicates oxide spallation.

Grahic Jump Location
Figure 9

Specimen mass change for various cast stainless steels during 100 h cycles in humid air at 800°C

Grahic Jump Location
Figure 10

Specimen mass change for CF8C+W,Cu uncoated and CVD aluminized exposed for 100 h cycles in humid air at 800°C

Grahic Jump Location
Figure 11

Polished cross section of CVD aluminized CF8C+Cu,W. The acicular precipitates are AlN that form due to the high N content in the alloy.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In