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 gamma-fcc phase with preferred crystal orientations. 90 sample, characterized by the largest grain size, lowest grain boundary density and fewest Cr-rich a 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.