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REJUVENATION OF PRE-CORRODED AND/OR PRE-FATIGUED 7075-T651 ALUMINUM ALLOY BY ULTRASONIC NANOCRYSTALLINE SURFACE MODIFICATION

Zhang, Ruixia
http://orcid.org/0000-0002-6171-7828
http://rave.ohiolink.edu/etdc/view?acc_num=akron1606754511716982

Abstract Details

2020, Doctor of Philosophy, University of Akron, Mechanical Engineering.
In this research, an innovative surface engineering process, ultrasonic nanocrystal surface modification (UNSM), was used to process a 7075-T651 aluminum alloy. It was observed that UNSM led to better surface finish, higher surface hardness, and the generation of an oxide layer on the surface of this alloy, in addition to beneficial compressive residual stresses in the near-surface region. Rotating–bending fatigue tests showed that UNSM processing significantly improved the fatigue performance of 7075-T651 aluminum alloy in both the low-cycle fatigue regimes and high-cycle fatigue regimes. Besides, the oxides that formed in the surface layer after UNSM treatment were found to prevent pitting corrosion of 7075-T651 aluminum alloy in a 3.5 wt% NaCl solution. Therefore, the fatigue performance of the UNSM-treated samples did not deteriorate after corrosion in a 3.5 wt% NaCl solution. These results demonstrate that UNSM is a robust surface modification method that can improve the rotating–bending fatigue resistance and pre-corrosion fatigue resistance of the 7075-T651 aluminum alloy. Furthermore, the fatigue life extension of the pre-damaged 7075-T651 aluminum alloy through UNSM treatment was investigated for the first time. It was found that the fatigue life of 7075-T651 aluminum alloy deteriorates after being immersed in a corrosion solution. However, UNSM treatment significantly recovered the fatigue life of the pre-corroded samples. Removal of corroded surface layer, the introduction of work-hardened surface region and compressive residual stress by UNSM treatment played a compelling role in the restoration of fatigue life of the pre-damaged sample. This result indicated that UNSM is a feasible method for rejuvenation of corrosion-damaged 7075-T651 aluminum alloy. UNSM also showed its powerful effectiveness to rejuvenate pre-fatigued 7075-T651aluminum alloy.
Yalin Dong (Advisor)
Chang Ye (Committee Member)
Guo-Xiang Wang (Committee Member)
Qixin Zhou (Committee Member)
En Cheng (Committee Member)
136 p.
Mechanical Engineering
Aluminum alloy; Rejuvenation; Ultrasonic nanocrystal surface modification; UNSM; Compressive residual stress; Rotating bending fatigue; Corrosion

Recommended Citations

Citations

  • Zhang, R. (2020). REJUVENATION OF PRE-CORRODED AND/OR PRE-FATIGUED 7075-T651 ALUMINUM ALLOY BY ULTRASONIC NANOCRYSTALLINE SURFACE MODIFICATION [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1606754511716982

    APA Style (7th edition)

  • Zhang, Ruixia. REJUVENATION OF PRE-CORRODED AND/OR PRE-FATIGUED 7075-T651 ALUMINUM ALLOY BY ULTRASONIC NANOCRYSTALLINE SURFACE MODIFICATION. 2020. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1606754511716982.

    MLA Style (8th edition)

  • Zhang, Ruixia. "REJUVENATION OF PRE-CORRODED AND/OR PRE-FATIGUED 7075-T651 ALUMINUM ALLOY BY ULTRASONIC NANOCRYSTALLINE SURFACE MODIFICATION." Doctoral dissertation, University of Akron, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1606754511716982

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Akron and OhioLINK.