Improving surface quality of IN625 alloy fabricated by selective laser melting using dry mechanical-electrochemical polishing technology

IN625 alloy is a solid solution-strengthened nickel-based superalloy. The corresponding components fabricated by selective laser melting (SLM) were widely applied in the aerospace field. However, the surface quality of IN625 alloy components formed directly by SLM is too poor to meet the requirements of high-precision applications. In this study, the surface morphology characteristics of the as-built IN625 samples were first analyzed. Then, the influence of SLM process parameters on the surface quality was investigated. Moreover, a dry mechanical-electrochemical polishing method was proposed to further improve the surface quality, where different combinations of polishing process parameters were designed to polish the IN625 parts. The influence of polishing process parameters on the polishing effect was also analyzed. Finally, a quadratic polynomial model of surface roughness with respect to voltage and time was established using a response surface methodology. In addition, the process was optimized with a goal of minimizing surface roughness. Through response surface methodology optimization, the surface roughness Sa value of the IN625 sample was reduced from 6.86 μm to 1.20 μm, a reduction of 82.5%. This study revealed the influence of SLM and dry mechanical-electrochemical polishing process parameters on the surface quality of the samples, as well as providing an effective polishing method for the additively manufactured metal components.