Corrosion behavior of Ti-6Al-4V alloy welded by scanning electron beam

The corrosion behavior of Ti-6Al-4V alloy welded by SEE (scanning electron beam) is described in this paper. Solidification macrostructure of weld was transformed from 650-mu m columnar crystals to 100-mu m equiaxed crystals by SEE. Anodic polarization behavior of the weld was different following th e change in solidification macrostructure. Anodic polarization curve of 150 -mu m equiaxed-grain weld coincided with that of base metal, which indicate d a best state of equal corrosion tendency between the base and the weld me tal. Alloy element homogeneity in the equiaxed solidification structures ma de the weld more corrosion resistant than the columnar solidification struc tures. Fine microstructure and a small quantity of dislocations have a good effect on uniform corrosion resistance of the weld, but coarse microstruct ure, a spinodal decomposition of the metastable beta-phase and a large quan tity of dislocations were related to the inferior resistance either to unif orm corrosion or to local corrosion. (C) 2000 Elsevier Science S.A. All rig hts reserved.