Surface Condition and Fatigue Crack Growth in an Aluminum Alloy

Abstract

Abbreviations aCrack length on non-scratched surface a'Crack length on scratched surface da/dN Crack growth rate Stress intensity factor due to compressive residual stress ΔΚ Stress intensity factor "tr Transition length from tensile to shear mode Abstract-The fatigue crack growth in Aluminum 2024-T3 alloy specimens whose surface were scratched has been investigated. The results in such specimens indicated an increased fatigue crack growth rate. Whereas, in scratched-shot peened specimens, crack growth rates were nearly equal those in as-received material. This useful influence occurred at low ΔΚ. However, as ΔΚ increased growth rates gradually increased and finally, merged with those of scratched specimens. When a through width scratch was combined with a through thickness scratch, crack growth rates exhibited characteristics of small crack behavior.