ON MOLIEN SERIES OF THE INVARIANT RING ASSOCIATED TO THE UNITARY REFLECTION GROUP G(m,p,n) G(m,p,n)

A novel application of the Friction stir processing (FSP) in surface modification of walls of the cylindrical hole is presented. Predrilled holes in commercially available aluminum plate were friction stirred using a specially fabricated tapered tool that rotates and simultaneously traverses through the hole. The tapered tool expands the hole to the desired diameter and also stirs the internal wall of the hole. In order to understand the role of frictional heating and stirring in the FSP of holes three mediums, namely, dry (without cooling and lubricating), metal working fluid (cooling and lubricating) and Al2O3 nanoparticles (lubricating and frictional heating) were used. The surface roughness and hardness of the wall of the holes were measured. Significant hardness improvement with reasonable surface finish is obtained. Moreover the FSPed holes showed improvement in the fatigue life of the holes. The results are promising enough however many more investigation need to be carried out to fully understand the physics of the process and subsequently apply the same at the shop-floor