Laser Peening For Improving Metallic Components

Suitable variation of residual stress profiles, fatigue strength and frequently also corrosion resistance of a material, are key requirements to be fulfilled for usability and long life of a vital machine component. Laser Peening (LP) is an innovative surface treatment which was initially developed for the aeronautic industry as the method for the improvement of the fatigue cracking resistance of the turbine spades of an aircraft, such as Falcon F-16 and Rockwell F-22. LP is based on plasma generation, which produces shock impact waves, which, in turn, produce elastoplastic shifts of atomic planes and generation of compressive residual stresses of high gradient [1]. LP has been applied to different types of steels, aluminium and titanium alloys [2]. In practice, technologists and engineers frequently require the introduction of compressive residual stresses since it improves fatigue resistance of a material [3, 4]. In the study [5] of the effects of LP parameters such as laser-beam power density, pulse duration, and pulse density it was found that a correct choice of the processing parameters enabled desired variations of micro-hardness and residual stresses in the surface of machine components. Such achieved condition provided improved material resistance to fatigue. The applicability of laser peening was also confirmed to improve stress-corrosion cracking [6].