Restoring Fatigue Performance of Corrosion Damaged Aa7075-T6 and Fretting in 4340 Steel with Low Plasticity Burnishing

摘要

Corrosion related fatigue in aluminum structural alloys and fretting damage in high strength steels are primary failure mechanisms that reduce the structural integrity of aging aircraft. A chemically active environment, susceptible material and static and/or alternating tensile stresses are all required for failure. Conventional approaches to mitigate corrosion and fretting related failure mechanisms address either elimination of the corrosive environment with coatings, substitution or modification of alloys, or changes in design, all expensive solutions. This paper describes an alternate approach, employing surface enhancement by low plasticity burnishing (LPB) to introduce a deep, stable layer of compressive residual stress to eliminate the tensile stresses necessary for failure without altering either material or design.