表面超声滚压对电子束选区熔化TC4合金微观组织及腐蚀行为的影响OA

TC4 alloys were manufactured by selective electron beam melting(SEBM)and subjected to ultrasonic surface rolling processing(USRP)in this study.The effects of USRP on the surface and microstructure of the alloys were investigated by optical microscopy,X-ray diffraction(XRD),and electron backscatter diffraction(EBSD).The corrosion behavior was analyzed with electrochemical testing methods.The results indicate that USRP causes the severe plastic deformation on the surface of SEBM-TC4 alloys,leading to the grain refinement,facilitating the formation of a gradient deformation layer(about 30 μm thick),and ultimately enhancing the surface finish and densification.In 3.5％mass fraction NaCl solution,the corrosion potential of the USRP-treated samples(-0.092 VSCE)is significantly higher than that of the sandpaper-ground samples(-0.216 VSCE),and the corrosion current density decreases by approximately 43.5％.Moreover,the passivation films on USRP-treated SEBM-TC4 exhibit a double-layer structure,with TiO2 in the outer layer and(TiO2+Ti2O3)in the inner layer.In summary,USRP improves the surface finish and densification of the metal,introduces the high-density dislocations in deformation layer to refine grains,and promotes the formation of a dense passivation film,notably improving the corrosion resistance of SEBM-TC4 alloys.