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Title: CONSTITUTION, METALLURGY, AND OXIDATION RESISTANCE OF IRON-CHROMIUM- ALUMINUM ALLOYS

Abstract

The constitution of iron-chromium -aluminum alloys was investigated employing high-purity materials. Ternary sections illustrating the results are presented. The limits of the alpha-plus-sigma region are found to extend from 33 to 63 wt.% chromium at 600 C. At 750 C these limits decreasc to 38 and 57 wt.% chromium. Sigma is found in alloys coataining a maximum of about 9 wt.% aluminum at 600 C and 4 wt.% aluminum at 750 C. The limits of the alpha solid-solution region were investigated between 500 and 900 C. No observable change in limits occurred between 500 and 750 C. However, between 750 and 900 C the AlCr/sub 2/ phase decomposes resulting in a slightly expanded alpha region in the high-chromium alloys. Sigma is found to be unstable below 600 C in alloys of sigma-phase composition. Sigma formation and decomposition occur reversibly above and below this temperature. The nature of the products of the reaction below 600 C has not been determined. A detailed investigation of the physical metallurgy of iron alloys containing 25 to 35 wt.% chromium and 3 to 8 wt.% aluminum, has been made in an attempt to define the limits of usefulness of these materials as structural materials. Itmore » is possible to melt and fabricate all alloys within this composition range, but extraordinary care must be used to avoid embritilement from undesirable impurities such as carbon, from oxide drosses, from un favorable grain size and structure, and from internal cracking caused by rapid cooling. Suitable methods for casting and fabricating these alloys are described. The deformation processes of iron-chromium -aluminum alloys are reported and a ductility transition which varies with alloy content is attributed to the interaction of a twinning mode of plastic deformation and a cleavage mode of fracture. The oxidation resistances of iron23.7 wt.% chromium- 6.0 wt.% aluminum alloy and of nickel-20.0 wt.% chromium-1.1 wt.% niobium alloy have been compared at 1040 and 1150 C in air atmospheres containing additions of (1) water vapor, (2) carbon dioxide, and (3) combinations of water vapor and carbon dioxide. The iron-chromium-aluminum alloy was more oxidation resistant than the nickel-chromium -niobium alloy in all atmospheres at 1150 C. Minimum oxidation of both alloys occurred in an atmosphere of air plus 2.5 vol.% water vapor. (auth)« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Battelle Memorial Inst., Columbus, Ohio
OSTI Identifier:
4290548
Report Number(s):
BMI-1298
NSA Number:
NSA-13-002969
DOE Contract Number:  
W-7405-ENG-92
Resource Type:
Technical Report
Resource Relation:
Other Information: Orig. Receipt Date: 31-DEC-59
Country of Publication:
United States
Language:
English
Subject:
METALLURGY AND CERAMICS; AIR; ALUMINUM ALLOYS; BRITTLENESS; CARBON; CARBON DIOXIDE; CASTING; CHROMIUM ALLOYS; COOLING; CRACKS; DECOMPOSITION; DEFORMATION; DUCTILITY; FABRICATION; FAILURES; GRAIN SIZE; HIGH TEMPERATURE; IMPURITIES; INTERMETALLIC COMPOUNDS; IRON ALLOYS; MELTING; METALLURGY; NICKEL ALLOYS; NIOBIUM ALLOYS; OXIDES; PHASE DIAGRAMS; SOLID SOLUTIONS; STABILITY; STANDARDS; TEMPERATURE; THERMODYNAMICS; VAPORS; WATER

Citation Formats

Chubb, W., Alfant, S., Bauer, A.A., Jablonowski, E.J., Shober, F.R., and Dickerson, R.F. CONSTITUTION, METALLURGY, AND OXIDATION RESISTANCE OF IRON-CHROMIUM- ALUMINUM ALLOYS. United States: N. p., 1958. Web. doi:10.2172/4290548.
Chubb, W., Alfant, S., Bauer, A.A., Jablonowski, E.J., Shober, F.R., & Dickerson, R.F. CONSTITUTION, METALLURGY, AND OXIDATION RESISTANCE OF IRON-CHROMIUM- ALUMINUM ALLOYS. United States. doi:10.2172/4290548.
Chubb, W., Alfant, S., Bauer, A.A., Jablonowski, E.J., Shober, F.R., and Dickerson, R.F. Thu . "CONSTITUTION, METALLURGY, AND OXIDATION RESISTANCE OF IRON-CHROMIUM- ALUMINUM ALLOYS". United States. doi:10.2172/4290548. https://www.osti.gov/servlets/purl/4290548.
@article{osti_4290548,
title = {CONSTITUTION, METALLURGY, AND OXIDATION RESISTANCE OF IRON-CHROMIUM- ALUMINUM ALLOYS},
author = {Chubb, W. and Alfant, S. and Bauer, A.A. and Jablonowski, E.J. and Shober, F.R. and Dickerson, R.F.},
abstractNote = {The constitution of iron-chromium -aluminum alloys was investigated employing high-purity materials. Ternary sections illustrating the results are presented. The limits of the alpha-plus-sigma region are found to extend from 33 to 63 wt.% chromium at 600 C. At 750 C these limits decreasc to 38 and 57 wt.% chromium. Sigma is found in alloys coataining a maximum of about 9 wt.% aluminum at 600 C and 4 wt.% aluminum at 750 C. The limits of the alpha solid-solution region were investigated between 500 and 900 C. No observable change in limits occurred between 500 and 750 C. However, between 750 and 900 C the AlCr/sub 2/ phase decomposes resulting in a slightly expanded alpha region in the high-chromium alloys. Sigma is found to be unstable below 600 C in alloys of sigma-phase composition. Sigma formation and decomposition occur reversibly above and below this temperature. The nature of the products of the reaction below 600 C has not been determined. A detailed investigation of the physical metallurgy of iron alloys containing 25 to 35 wt.% chromium and 3 to 8 wt.% aluminum, has been made in an attempt to define the limits of usefulness of these materials as structural materials. It is possible to melt and fabricate all alloys within this composition range, but extraordinary care must be used to avoid embritilement from undesirable impurities such as carbon, from oxide drosses, from un favorable grain size and structure, and from internal cracking caused by rapid cooling. Suitable methods for casting and fabricating these alloys are described. The deformation processes of iron-chromium -aluminum alloys are reported and a ductility transition which varies with alloy content is attributed to the interaction of a twinning mode of plastic deformation and a cleavage mode of fracture. The oxidation resistances of iron23.7 wt.% chromium- 6.0 wt.% aluminum alloy and of nickel-20.0 wt.% chromium-1.1 wt.% niobium alloy have been compared at 1040 and 1150 C in air atmospheres containing additions of (1) water vapor, (2) carbon dioxide, and (3) combinations of water vapor and carbon dioxide. The iron-chromium-aluminum alloy was more oxidation resistant than the nickel-chromium -niobium alloy in all atmospheres at 1150 C. Minimum oxidation of both alloys occurred in an atmosphere of air plus 2.5 vol.% water vapor. (auth)},
doi = {10.2172/4290548},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1958},
month = {10}
}