All samples show a fine homogeneous tempered martensitic microstructure with a prior austenite.
No elongated austenite grains were found. The microstructure is free of delta-ferrite and segregation bands of carbides. To a lesser extent, concentrations of Ta-rich phases were also found. Ta appears to precipitate as relatively large particles, with respect to carbides present. The hardness shows an even distribution over the cross sections, without evident hardness decrease at the plate surfaces.