Study Of Electrolytic Polishing Process On The Surface Of Selective Laser Melting Formed Complex Components

Additive manufacturing technology based on the principle of layer-by-layer melt forming and layer-by-layer accumulation can form parts with very complex geometries,providing a solution for forming complex,lightweight and integrated parts.However,the surface quality of SLM-formed parts is relatively poor and cannot be directly used in engineering applications.In order to obtain a flat and smooth surface and excellent physical and mechanical properties,and improve the durability of the parts,various polishing methods have been developed.At present,traditional mechanical polishing methods are widely used,but there are problems such as dependence on the skill level of operators,precision of polishing equipment,many processes and low efficiency.Especially when dealing with complex parts with high performance requirements(such as aero-engine turbine blades,fuel nozzles,etc.),the inner surface polishing process is more complicated,the accuracy and stability of artificial completion cannot be guaranteed,and the efficiency is low.In view of this problem,this paper chooses to conduct electrolytic polishing on complex316L stainless steel specimens formed by SLM in environment-friendly alcohol-based electrolyte,sets up electrolytic polishing equipment,and completes the orthogonal experimental study of electrolytic polishing.The main research contents are as follows:(1)Introduced the principle and characteristics of SLM technology,the current research status of SLM equipment,the main defects and causes of SLM forming,the current research status of SLM forming stainless steel materials and the current research status of SLM process parameters.(2)Introduces the research progress of polishing processing,including the traditional honing,grinding and finishing grinding polishing methods and their principles and characteristics,also including some emerging polishing methods,such as abrasive flow polishing,laser polishing,chemical polishing and electrolytic polishing and other principles and characteristics and research status.(3)A more environmentally friendly and safe electrolyte mixed with ethylene glycol and sodium chloride was prepared.The electrolytic polishing device was built,and the ring electrode was selected to ensure the same distance between cathode and anode,and the power supply was 0?30V DC power supply.A digital display temperature-controlled stirrer was selected to control the temperature of the electrolytic polishing and to stir the solution.The experimental platform was finally built and commissioned and trial run for the basic experimental research of this article.(4)To carry out orthogonal experimental research on electrolytic polishing.Considering the experimental cost and the reliability of the results,a set of orthogonal tests was designed to investigate the effects of three key process parameters(voltage,electrolyte concentration and temperature)on the electrolytic polishing process.The results showed that voltage had the most significant effect on the effect of electrolytic polishing;followed by electrolyte concentration;and finally,temperature.The best combination of process parameters for electrolytic polishing was:voltage of 8.5 V,electrolyte concentration of0.8mol/L,temperature of 60°C,and minimum surface roughness of 0.56?m.(5)The changes of surface roughness,surface morphology,surface elements,physical phase,metallographic phase,surface hardness and corrosion resistance of the parts after electrolytic polishing and mechanical polishing were compared and analyzed.The results showed that the Cr content of the parts increased after electrolytic polishing and mechanical polishing,and the dense Cr₂O₃ oxide film was more easily generated on the surface,which improved the corrosion resistance of the specimens.The hardness of the specimen decreased slightly after electrolytic polishing,while the hardness of the specimen increased slightly after mechanical polishing.The surface roughness of the parts was greatly reduced and the corrosion resistance was improved after electrolytic polishing and mechanical polishing,and no new phases were generated and the grains grew to a small extent.Electrolytic polishing is a non-contact,non-damaging process,and it can improve the corrosion resistance of metals,which is particularly important for applications in biomedical materials and aerospace materials.The research in this paper broadens the path and provides a strong scientific basis for the application of complex 316L stainless steel parts formed by SLM in various fields in the future.Figure[42]Table[11]Reference[101]...