skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Alumina-Forming Austenitic Stainless Steels Strengthened by Laves Phase and MC Carbide Precipitates

Abstract

Creep strengthening of Al-modified austenitic stainless steels by MC carbides or Fe{sub 2}Nb Laves phase was explored. Fe-20Cr-15Ni-(0-8)Al and Fe-15Cr-20Ni-5Al base alloys (at. pct) with small additions of Nb, Mo, W, Ti, V, C, and B were cast, thermally-processed, and aged. On exposure from 650 C to 800 C in air and in air with 10 pct water vapor, the alloys exhibited continuous protective Al{sub 2}O{sub 3} scale formation at an Al level of only 5 at. pct (2.4 wt pct). Matrices of the Fe-20Cr-15Ni-5Al base alloys consisted of {gamma} (fcc) + {alpha} (bcc) dual phase due to the strong {alpha}-Fe stabilizing effect of the Al addition and exhibited poor creep resistance. However, adjustment of composition to the Fe-15Cr-20Ni-5Al base resulted in alloys that were single-phase {gamma}-Fe and still capable of alumina scale formation. Alloys that relied solely on Fe{sub 2}Nb Laves phase precipitates for strengthening exhibited relatively low creep resistance, while alloys that also contained MC carbide precipitates exhibited creep resistance comparable to that of commercially available heat-resistant austenitic stainless steels. Phase equilibria studies indicated that NbC precipitates in combination with Fe{sub 2}Nb were of limited benefit to creep resistance due to the solution limit of NbC within themore » {gamma}-Fe matrix of the alloys studied. However, when combined with other MC-type strengtheners, such as V{sub 4}C{sub 3} or TiC, higher levels of creep resistance were obtained.« less

Authors:
 [1];  [1];  [1];  [1];  [2];  [1];  [1]
  1. ORNL
  2. Tokyo Institute of Technology
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shared Research Equipment Collaborative Research Center
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program; FE USDOE - Office of Fossil Energy (FE); USDOE Office of Science (SC)
OSTI Identifier:
936279
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Metallurgical and Materials Transactions A; Journal Volume: 38A; Journal Issue: 11
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AIR; ALLOYS; CARBIDES; CREEP; LAVES PHASES; MATRICES; STAINLESS STEELS; WATER VAPOR

Citation Formats

Yamamoto, Yukinori, Brady, Michael P, Lu, Zhao Ping, Liu, Chain T, Takeyama, Masao, Maziasz, Philip J, and Pint, Bruce A. Alumina-Forming Austenitic Stainless Steels Strengthened by Laves Phase and MC Carbide Precipitates. United States: N. p., 2007. Web. doi:10.1007/s11661-007-9319-y.
Yamamoto, Yukinori, Brady, Michael P, Lu, Zhao Ping, Liu, Chain T, Takeyama, Masao, Maziasz, Philip J, & Pint, Bruce A. Alumina-Forming Austenitic Stainless Steels Strengthened by Laves Phase and MC Carbide Precipitates. United States. doi:10.1007/s11661-007-9319-y.
Yamamoto, Yukinori, Brady, Michael P, Lu, Zhao Ping, Liu, Chain T, Takeyama, Masao, Maziasz, Philip J, and Pint, Bruce A. Mon . "Alumina-Forming Austenitic Stainless Steels Strengthened by Laves Phase and MC Carbide Precipitates". United States. doi:10.1007/s11661-007-9319-y.
@article{osti_936279,
title = {Alumina-Forming Austenitic Stainless Steels Strengthened by Laves Phase and MC Carbide Precipitates},
author = {Yamamoto, Yukinori and Brady, Michael P and Lu, Zhao Ping and Liu, Chain T and Takeyama, Masao and Maziasz, Philip J and Pint, Bruce A},
abstractNote = {Creep strengthening of Al-modified austenitic stainless steels by MC carbides or Fe{sub 2}Nb Laves phase was explored. Fe-20Cr-15Ni-(0-8)Al and Fe-15Cr-20Ni-5Al base alloys (at. pct) with small additions of Nb, Mo, W, Ti, V, C, and B were cast, thermally-processed, and aged. On exposure from 650 C to 800 C in air and in air with 10 pct water vapor, the alloys exhibited continuous protective Al{sub 2}O{sub 3} scale formation at an Al level of only 5 at. pct (2.4 wt pct). Matrices of the Fe-20Cr-15Ni-5Al base alloys consisted of {gamma} (fcc) + {alpha} (bcc) dual phase due to the strong {alpha}-Fe stabilizing effect of the Al addition and exhibited poor creep resistance. However, adjustment of composition to the Fe-15Cr-20Ni-5Al base resulted in alloys that were single-phase {gamma}-Fe and still capable of alumina scale formation. Alloys that relied solely on Fe{sub 2}Nb Laves phase precipitates for strengthening exhibited relatively low creep resistance, while alloys that also contained MC carbide precipitates exhibited creep resistance comparable to that of commercially available heat-resistant austenitic stainless steels. Phase equilibria studies indicated that NbC precipitates in combination with Fe{sub 2}Nb were of limited benefit to creep resistance due to the solution limit of NbC within the {gamma}-Fe matrix of the alloys studied. However, when combined with other MC-type strengtheners, such as V{sub 4}C{sub 3} or TiC, higher levels of creep resistance were obtained.},
doi = {10.1007/s11661-007-9319-y},
journal = {Metallurgical and Materials Transactions A},
number = 11,
volume = 38A,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}