A novel approach to measure three-dimensional surface topography for stationary shoulder friction stir processing

We demonstrate a stationary shoulder friction stir processing (SSFSP) to produce smooth surface finish due to non-rotating action of the shoulder. The present work aims to investigate surface topography of high strength AA7075 aluminum alloy processed by SSFSP at different rotational speeds. The unique approach of 3D surface mapping under high-end digital microscopy carried out to evaluate qualitative as well as quantitative surface behavior of the processed region. The surface topography indicated the little amount of flash generation on the processed zone, while 3D mapping of the surface quantified the surface roughness in longitudinal (PD) as well as transverse direction (ND) of the processing zone. Surface analysis confirmed that amount of flash generation was relied on tool rotational speed. The overall surface roughness characterized by average and peak values in both the directions, demonstrating better surface finish in ND at the higher tool rotation, while better uniformity in PD.