A comparison of AA2024 and AA7150 subjected to ultrasonic shot peening: Microstructure, surface segregation and corrosion

  • Qingqing Sun
  • , Xingtao Liu
  • , Qingyou Han
  • , Jie Li
  • , Rong Xu
  • , Kejie Zhao

Research output: Contribution to journalArticlepeer-review

73 Scopus citations

Abstract

The influence of ultrasonic shot peening (USSP) on microstructure, surface segregation, localized and electrochemical corrosion of AA2024 was investigated using immersion test, OCP, EIS, polarization, XRD and SEM-EDS methods. The results are compared with those of AA7150. Like AA7150, second phase particles of AA2024 peened surface layer dissolved into Al matrix due to the extended solid solubility caused by USSP. After USSP, corrosion rate of AA2024 increased by 2–3 times due to surface contamination, however, intergranular corrosion (IGC) resistance of AA2024 is significantly enhanced by USSP treatment. The improvement in localized corrosion resistance is mainly attributed to grain refinement and microstructure homogenization. As opposed to AA7150, OCP of AA2024 in 3.5 wt% NaCl solution (pH = 5.8) shifts to more noble direction after USSP. This is due to the different surface segregation behaviours of the two studied alloys. The mechanism of surface segregation is also briefly discussed.

Original languageEnglish
Pages (from-to)552-560
Number of pages9
JournalSurface and Coatings Technology
Volume337
DOIs
StatePublished - 15 Mar 2018
Externally publishedYes

Keywords

  • AA2024
  • AA7150
  • Corrosion
  • Surface nanocrystallization
  • Surface segregation
  • Ultrasonic shot peening

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