Accession Number : ADA607788


Title :   Systematic Review of Uit Parameters on Residual Stresses of Sensitized AA5456 and Field Based Residual Stress Measurements for Predicting and Mitigating Stress Corrosion Cracking


Descriptive Note : Master's thesis


Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA


Personal Author(s) : Haggett, Michelle E


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a607788.pdf


Report Date : Mar 2014


Pagination or Media Count : 133


Abstract : This thesis focuses on the use of x-ray diffraction to measure residual stresses around welds in aluminum ship structures both in the laboratory and in the field. Tensile residual stresses are often generated during welding and, in sensitized aluminum structures, can cause extensive stress corrosion cracking. Peening techniques, such as ultrasonic impact treatment (UIT), can mitigate and even reverse these tensile residual stresses. This research uses x-ray diffraction to measure residual stresses around welds in AA5456 before and after UIT. In particular, we examined the importance of UIT parameters such as peening amplitude and pin size. We found that all combinations of UIT parameters removed the tensile residual stresses and resulted in compressive stress several hundred microns below the weld surface. The exact level of compressive residual stress was sensitive to the pin size used with a smaller, but measurable, dependence upon the displacement amplitude. In an effort to extend these measurement techniques to the field, we successfully performed the first x-ray residual stress measurements on a U.S. naval combatant.


Descriptors :   *ALUMINUM , *CRACKS , *RESIDUAL STRESS , *STRESS CORROSION , *STRUCTURES , *X RAY DIFFRACTION , CRACK PROPAGATION , DISPLACEMENT , LABORATORIES , MEASUREMENT , NAVAL VESSELS(COMBATANT) , SHOT PEENING , TENSILE STRESS , ULTRASONICS , WELDING


Subject Categories : Inorganic Chemistry
      Properties of Metals and Alloys
      Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE