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PhD Dissertation (M.Seifi)-Final.pdf (23.55 MB)

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Sensitization Effects on Environmentally Assisted Cracking of Al-Mg Naval Alloys

Seifi, Mohsen
http://orcid.org/0000-0001-8385-2337
http://rave.ohiolink.edu/etdc/view?acc_num=case1450805183

Abstract Details

2015, Doctor of Philosophy, Case Western Reserve University, Materials Science and Engineering.
Al-Mg 5xxx alloys are desirable in a wide array of structural applications that require a weldable alloy with good corrosion resistance. However, significant changes in the mechanical properties have been shown to occur after both short-term high temperature (e.g. 175°C, < 100 hours) and long-term low temperature (e.g. 60°C, 1000's hrs) laboratory thermal exposures. Commercially available 5083-H116, 5456-H116 and 5083-H131 alloy plates were thermally exposed to various low and intermediate temperatures for times in excess of 20,000 hrs. Significant changes to the strength and fatigue crack growth behavior have been observed after such exposures. In particular, the longitudinal splitting in the short-transverse (ST) direction has been exhibited during fatigue crack growth of L-T samples tested in laboratory air after sufficient time and temperature exposure combinations. In order to directly examine environmental effects on cracking in the ST plane, slow strain rate tensile tests have been conducted in the S-T orientation in various environments (e.g. Lab Air, Dry, and Corrosive). These tests showed significant reductions in ductility and time to failure depending upon the degree of sensitization and type of environment. In order to quantify these effects in more details, environmentally enhanced cracking experiments using J-based fracture mechanics tests were conducted in similar environments on fatigue-precracked samples in the S-T orientation. The evolution of properties (i.e. fracture/fatigue) and the effects of microstructural features (e.g. grain boundary segregation, grain boundary precipitation, grain orientation and misorientation, etc.) and environmentally enhanced cracking are provided along with the effects of various remediation treatments.
John Lewandowski (Advisor)
Henry Holroyd (Committee Member)
Rimnac Clare (Committee Member)
Schwam David (Committee Member)
233 p.
Engineering; Materials Science; Metallurgy
Sensitization; environmentally assisted cracking; fatigue, fracture, slow strain rate tensile testing, delamination, splitting

Recommended Citations

Citations

  • Seifi, M. (2015). Sensitization Effects on Environmentally Assisted Cracking of Al-Mg Naval Alloys [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1450805183

    APA Style (7th edition)

  • Seifi, Mohsen. Sensitization Effects on Environmentally Assisted Cracking of Al-Mg Naval Alloys. 2015. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1450805183.

    MLA Style (8th edition)

  • Seifi, Mohsen. "Sensitization Effects on Environmentally Assisted Cracking of Al-Mg Naval Alloys." Doctoral dissertation, Case Western Reserve University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1450805183

    Chicago Manual of Style (17th edition)

case1450805183
638
© 2015, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.