Comparison of two-step surface treatment on surface roughness and corrosion resistance of TC4 alloy parts prepared by SLM and SEBM

Abstract

To reduce the surface defects of additive manufacturing forming parts and improve surface quality such as surface roughness and corrosion resistance, a two-step surface treatment technology, namely, pre -polishing combined with micro-arc oxidation (MAO), is employed to treat bulk samples constructed by selective laser melting (SLM) and selective electron beam melting (SEBM), respectively. Effects of surface morphology and coating thickness on surface roughness and corrosion resistance are systematically studied. Results show that the two-step surface treatment weakens the step effect of the original sample surface distinctively. Meanwhile, the MAO coating can improve the corrosion resistance of the original sample significantly. The corrosion current density Icorr of SLM specimen- is reduced from 6.212 × 10−5 A/cm2 to 2.493 × 10−7 A/cm2 (t = 15 min), and the Icorr of SEBM specimen- is reduced from 8.013 × 10−6 A/cm2 to 2.562 × 10−6 A/cm2 (t = 15 min).