Electron Beam Surface Modification of Cobalt Chrome Molybdenum Alloy Formed by a Laminate Molding Method

摘要

We used electron beam irradiation on a laminate molded Co-Cr-Mo bulk alloy to reduce the surface roughness and increase hardness. The accelerating voltage and beam current were 40 kV and 0.5~5.0 mA, respectively. Irradiation time for each dot was 0.1 ms and the distance between dots (dot pitch) was either 0.2 or 0.4 mm, which corresponded to a scanning speed of 200 or 400 mm/s, respectively. The roughness value, Ra, decreased to 0.3-0.45 μm for a beam current of 1 mA and a dot pitch of 0.02 mm. The coarse grains present in the base alloy were refined to sizes of less than 1 (Am by rapid solidification. An increase in the Knoop hardness from 470 HK for the base metal to about 550 HK was achieved by this technique.