Literature Review – I

As an active member in the surface modification field, LSPT routinely reviews technical papers published on surface modification technologies.  To share some of the information that is currently available in the community with our customers, we are introducing a new feature where we review a published article from the array of journals available and note a few key items.  The first paper to be reviewed in this series is titled “Comparison of mechanisms of advanced mechanical surface treatments in nickel-based superalloy” by A. Gill et al.  The abstract and images from the article are available at http://www.sciencedirect.com/science/article/pii/S0921509313004036.
This article compares the effects of cavitation peening, laser peening, and a process known as ultrasonic nano structure modification (UNSM) on IN 718 (nickel based super alloy) 2mm thick sheet.  For the benefit of new readers, the article discusses the different surface modification methods in brief before diving into technical details.
Some of the finer details of the laser peening process used on the coupons, such as the overlays and application sequence, were not discussed in the article but are important characteristics in the results achieved.  The resulting residual stress profiles suggested that laser peening generates compressive stresses that extend approximately 2x as deep as the other methods used.  The article also discusses some of the other changes that occur to surface finish, hardness, and microstructure as a result of the different processes.
IN 718 is typically used in high temperature environments.  LSPT looks forward to continued research that documents the performance of these different technologies at elevated temperatures and will be sure to add some discussion for our customers as information is released.