Stress corrosion cracking of Fe{sub 3}Al and Fe-16% Al alloys

Journal Article · Thu May 01 04:00:00 EDT 1997 · Corrosion

DOI:https://doi.org/10.5006/1.3280478· OSTI ID:495434

Kim, J G ^[1]; Buchanan, R A ^[2]

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1. Sung Kyun Kwan Univ., Suwon (Korea, Republic of). Dept. of Metallurgical Engineering
2. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering

The stress corrosion cracking (SCC) susceptibilities of an Fe{sub 3}Al-based iron aluminide (Fe-28% Al-2% Cr[at%]) and a lower-Al disordered Fe-Al alloy (Fe-16% Al-5% Cr-1% Mo [at%]) were investigated using U-bend and slow strain rate tests (SSRT) in a mild acid-chloride solution (200 ppm Cl{sup {minus}} [5.5 {times} 10{sup {minus}3} M sodium chloride], pH = 4 [6.3 {times} 10{sup {minus}5} M sulfuric acid]). U-bend tests were conducted at anodic pitting potentials, at freely corroding open-circuit potentials and at cathodic hydrogen evolution potentials. For the higher-Al iron aluminide, cracking occurred within 200 h only at the highly negative cathodic potentials. These results indicated the cracking mechanism was related to hydrogen embrittlement (HE). For the lower-Al Fe-Al alloy, cracking did not occur at any of the potentials. Slow strain rate ductilities decreased significantly for both alloys with the onset of pitting corrosion (high anodic potentials) or the production of hydrogen (very negative cathodic potentials). Ductilities of the lower-Al alloy were much higher than those of the iron aluminide at the freely corroding potentials and hydrogen-evolution cathodic potentials. It was concluded that the cracking mechanisms were related to anodic dissolution (i.e., the effects of pitting corrosion at the high anodic potential and to HE at the very negative cathodic potentials) and that the lower-Al, disordered Fe-Al alloy was more resistant to HE than the Fe{sub 3}Al-based iron aluminide.

• Sponsoring Organization: USDOE Assistant Secretary for Fossil Energy, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 495434
• Journal Information: Corrosion, Journal Name: Corrosion Journal Issue: 5 Vol. 53; ISSN 0010-9312; ISSN CORRAK
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CHROMIUM ALLOYS
CORROSIVE EFFECTS
CRACK PROPAGATION
HYDROGEN EMBRITTLEMENT
IRON BASE ALLOYS
MOLYBDENUM ADDITIONS
PITTING CORROSION
SODIUM CHLORIDES
STRESS CORROSION