Title : Surface modification of ferrous metal alloys by nano-second laser shock peening
Abstract:
Laser Shock Peening is a promising surface enhancement technique applied to variety of metal materials to improve their surface, microstructure and mechanical properties. The induced compressive residual stress through laser shock peening is beneficiary to retard the crack initiation and propagations to extend the fatigue life of the engineering components.
This present work tried to bring necessary developments to implement low energy laser shock peening technique on few ferrous and non-ferrous metal alloys using Q-switched Nd: YAG laser with the fundamental wavelength of 1064 nm. Also, we have implemented laser shock peening without any protective layer coating called laser shock peening without coating technique for cost-effective processing. The work initially tried to optimize the laser pulse density or pulse overlapping to induce maximum compressive residual stress in case of laser shock peening without coating for the metal alloys such as Medium Carbon Spring Steel SAE 9254 and Austenitic Stainless Steel AISI 304. Later, we tried to apply laser shock peening for the severe surface plastic deformations called laser shock surface nanocrystallization by optimizing the number of impacts for the metal alloys Medium Carbon Spring Steel SAE 9254, Duplex Stainless Steel SAF 2205 and Nickel base Super alloy Inconel 718.
This thesis work tried to provide a practical solution to improve the functional life and performance of advanced materials for the desired applications. The work also focuses on bridging the knowledge gaps in understanding the key surface properties resulting from Laser Shock Peening that would aid in improving the key surface microstructure and mechanical properties. The ensuing results are expected to provide not only new and cost-effective pathways for designing and manufacturing engineering components with the required mechanical properties and hence structural integrity and reliability, but also new scientific insights into processing-microstructure-property relationships of these materials, which are all of great importance for cost savings. Such results would be of great utility in engineering, nuclear and biomedical applications. In turn, these advancements are expected to have a cross-cutting impact across all advanced materials and researchers, as well as those in materials processing sector in their development of effective manufacturing methods for advanced materials.
