Effect of process parameters on surface topography of friction stir welding

The surface topography of friction stir welding (FSW) plays an important role in the performance of joints. In this paper. the principle of surface texture of FSW was investigated in detail. The AA7075 aluminum alloy was friction stir welded at different rotational speeds and welding speeds, and the effect of process parameters on the surface topography was studied. The fractal dimension of the surface topography was calculated using the pixel-covering method. Moreover, the relationship between the surface topography and the fractal dimension was obtained. The results show that the surface arc texture spacing becomes smaller with the increase of the rotational speed and larger with the increase of the welding speed. There is a corresponding relationship between the fractal dimension of the surface topography and the surface roughness. The larger the surface roughness is, the larger the fractal dimension is.