Statistical Analysis of Surface Roughness of Ti–6Al–4V Products Manufactured by Selective Electron Beam Melting

A statistical study was made of the microgeometry parameters of the surface of vertical walls of an object of building by additive manufacturing using electron beam melting, and the effect of conditions of building and parameters of hatching mode on surface roughness was estimated. It was determined that the parameters of hatching mode affect the roughness of the lateral surface when building samples with vertical walls. It was shown that the average height of surface roughness, Rz, increases as the energy of hatching mode is intensified. A physical model was proposed to describe the effect of parameters of hatching mode on the roughness of vertical walls, which is based on the hypothesis that a melt microflow can penetrate during hatching onto the external surface of the contour. It was demonstrated that the distribution of surface roughness values of vertical walls is non-Gaussian, and the curves are typically right-skewed (the mode is located to the left of the center of size grouping), which indicates the influence of non-random factors whose number or values systematically change over time.