Transactions of the Indian Institute of Metals

, Volume 71, Issue 12, pp 3021–3027 | Cite as

Enhancing the Environmentally Assisted Cracking Resistance of Aircraft Quality Al Alloy of Type AA7075 Stiffened with Polymer Matrix Composite Using Cerium Chloride Inhibitor

  • S. S. KaleEmail author
  • V. S. Raja
  • A. K. Bakare
Technical Paper


This study explores a methodology to raise environmentally assisted cracking resistance of alclad Al–Zn–Mg–Cu (AA7075) alloy, used in aircraft structures, stiffened with polymer matrix composite asymmetric patch in order to suppress growth of fatigue cracks. Fracture mechanics studies of adhesively bonded center-pre-cracked Al alloy specimens having stiffeners were carried out in 3.5 wt% sodium chloride environment to understand the effect of cerium chloride inhibitor on the threshold stress intensity for stress corrosion cracking as well as the second-stage (steady-state) crack growth rate. It was observed that in the peak- and the two-step-aged tempers, the crack growth rate of the alloy reduced by two and a half, and four times, respectively, while the threshold stress intensity increased by 14–15% due to the addition of 1000 ppm of this inhibitor. The study offers a method to enhance significantly life of aging aircrafts stiffened with polymer matrix composite.


Aluminum alloy Polymer matrix composite Cerium chloride Inhibitor Stress corrosion Asymmetric stiffener 



One of the authors, S. S. Kale, expresses sincere gratitude to Mr. P. Jayapal, Chief Executive (Airworthiness) and Mr. G. Gouda, Group Director (Propulsion), CEMILAC, DRDO, Bangalore, for providing opportunity, support and encouragement for research in the field of life extension of aircraft materials. He further expresses his sincere thanks to the management of HAL (Foundry & Forge), Bangalore, for extending the test facilities and required support during the progress of this work.


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Copyright information

© The Indian Institute of Metals - IIM 2018

Authors and Affiliations

  1. 1.Regional Centre for Military Airworthiness (F&F), CEMILAC, DRDOBangaloreIndia
  2. 2.Department of Metallurgical Engineering and Materials ScienceIIT BombayMumbaiIndia
  3. 3.Regional Centre for Military Airworthiness (Nsk), CEMILAC, DRDONasikIndia

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