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  • In Situ Near Crack Tip pH Measurements to Confirm Alkaline Crack Conditions Causing Crack Arrest in Cathodically Polarized AA5456-H116
Title: In Situ Near Crack Tip pH Measurements to Confirm Alkaline Crack Conditions Causing Crack Arrest in Cathodically Polarized AA5456-H116
In situ crack tip pH measurements for corrosion fatigue (CF) cracks in sensitized AA5456-H116 loaded under low loading frequencies show that cathodic polarization can arrest actively growing stress corrosion cracking (SCC) and CF cracks and produce a local alkaline crack tip pH. A method for measuring crack tip pH in situ was developed. For AA5456-H116 under a single level of high sensitization, CF experiments while loading in the Paris regime at a loading frequency of 0.1 Hz were conducted under freely corroding conditions and a cathodic polarization of −1.3 VSCE. Results show that under freely corroding conditions the crack actively grows, and the crack tip pH is slightly acidic, while at −1.3 VSCE an alkaline crack tip develops with a pH of 10 to 12. The findings of this study support the earlier published hypothesis that crack arrest of SCC and low loading frequency CF cracks is due to corrosion-induced blunting after the development of highly alkaline conditions that cause corrosion of the crack tip region blunting and halting the crack.  more » « less
Award ID(s):
1943870
PAR ID:
10590549
Author(s) / Creator(s):
; ; ; ; ; ; ;
Publisher / Repository:
AMPP
Date Published:
Journal Name:
Corrosion
Volume:
80
Issue:
8
ISSN:
0010-9312
Page Range / eLocation ID:
828 to 835
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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