Modification of Materials Local Properties by Friction Stir Processing

Abstract

Friction stir processing (FSP) is a new solid state processing technique that can eliminate casting defects and refine microstructures, enhancing formability and improving other properties. FSP can also produce fine-grained microstructures through thickness. Essentially, FSP is a local thermo-mechanical metal working process that changes the local properties without influencing the properties of the bulk material. Firstly, the paper introduces FSP fundamental parameters, as advancing and rotating tool speed, approaching their influence on the processed surface roughness of Al6061. Single and overlapped friction stir processed layers were considered for the roughness analysis. Roughness mapping revealed existence of transitory and quasi-stationary phases of FSP. A process monitoring method obtaining through roughness control is envisaged. The paper also presents the material flow, microstructure and hardness in case of aluminium processed by FSP