Corrosion behaviour of CoCrMo alloy fabricated by electron beam melting

Electrochemical and static immersion tests in 1 mass% lactic acid solution are performed to investigate the corrosion behaviour of CoCrMo alloy fabricated by electron beam melting with cylindrical axes of samples deviating from build direction by 0°, 45° and 90°. All samples are dominantly composed of columnar γ-fcc phase with preferred crystal orientations. 90° sample, characterized by the largest grain size, lowest grain boundary density and fewest Cr-rich σ phase precipitates, demonstrates the highest corrosion resistance. The results suggest that amount of Cr-rich precipitates and grain boundary density both have much closer relation with corrosion resistance than crystal orientation.