Improving the surface integrity of 3D printed stainless steel parts by laser polishing

The paper details research aimed at improving the surface integrity of 3D printed stainless steel (SS316L) specimens by employing laser polishing. The effects of laser fluence, pulse distance and hatching strategies on resulting surface integrity were initially investigated in three phases of experiments in order to identify the optimum processing window. An optical metrology system based on ‘Focus Variation’ technology was used to capture the necessary surface data that was then utilised to analyse the laser polishing results. The results showed that a reduction in surface roughness of over 90% (from ~3 to ~0.3 µm S_a) was obtained when utilising the optimum process conditions without compromising the geometrical accuracy achieved by the preceding 3D printing process. The laser polishing technology was then implemented on meso-scale stainless steel components, which was successful in reducing S_a and S_t by 75% (0.489 to 0.126 µm) and 90% (17.71 to 1.21 µm) respectively. Furthermore, the laser polished surfaces exhibited none of the scratch marks, pits, holes, lumps and irregularities observed with the as-received SS samples.