Improved mechanical properties of nano structured 316 L stainless steel by statistically optimized low pulsed laser shock peening process for aeronautical application

Abstract

One of the most prominent methods of surface treatment techniques that outperforms other contemporary methods is laser shock peening (LSP) process. Although several materials have been studied for the improvement of their mechanical properties through LSP treatment, 316 L stainless steel (SS) has been the subject of comparatively fewer investigations. As a result, this article examines the effect of TOPSIS based Taguchi optimized Low Pulsed LSP (LP-LSP) process on the mechanical behaviour of 316 L SS. For this purpose, the optimal process conditions and their influence on the behaviour of hardness, compressive residual stress, roughness, wear and corrosion resistance are investigated in this study. From the statistically optimized robust design of experiments, the optimized parameters were computed to be 400 mJ pulse energy, two laser spots with 2 mm spot diameter. The results showed enhanced average hardness and surface roughness of the optimized LP-LSPed sample by 2.7 times and 50.46 % respectively and reduced wear and corrosion rate by 67.5 % and 98.61 % respectively over the unpeened sample. The deformation-induced modifications and grain refinement of the optimized LP-LSPed sample were examined under the optical microscope, scanning electron microscope and high-resolution transmission electron microscope and x-ray diffraction analysis.