Abstract:

Steels 45 and T12 were boronized using a plain boride agent and a series of  Nd2O3containing boride agents in a temperature range of 1053~1213 K to obtain the singleborided and rare earch(RE)borided layers. The effect of the RE on the boronization kinetics was analyzed. The results show that addition of RE accelerates formation of Fe2B phase, consequently increases the fraction of Fe2B phase in boride layer, improves its microstructure and performance. RE increases the diffusion coefficient and decreases the diffusion activation energy of the boron atom:from 184 to 122 kJ/mol for steel 45 and from 261 to 155 kJ/mol for steel T12,i.e. it is reduced by 34% and 41% respectively, enhancing effectively the boronizing rate. The contour diagram of the boride layer thickness of the steel 45 boronized with 5%Nd2O3 addition was built according to experimental data.

Key words: metallic material, rare earth(RE), boronization kinetics