Enhanced boronizing kinetics and high temperature wear resistance of H13 steel with boriding treatment assisted by air blast shot peening

- The boronizing kinetics of ABSP sample can be enhanced effectively.
- The fatigue spall of borides at the edge of wear scar was prevented by ABSP.
- The oxidative wear was relieved for borided samples with wear tests at 700 °C.

A nanostructured surface layer was fabricated on H13 steel by means of air blast shot peening (ABSP). A much thicker borided layer on the ABSP sample can be synthesized by a duplex boronizing treatment (DBT) at 600 °C for 2 h, which is followed by at a higher temperature for a certain time. The borided layer was composed with monophase of Fe2B and the growth of it exhibited a (002) preferred orientation. Moreover, the activation energy of boron diffusion for the ABSP sample is 227.4 kJ/mol, which is lower than 260.4 kJ/mol for the coarse-grained counterpart. The results indicate that the boronizing kinetics can be effectively enhanced in the ABSP sample with DBT. The high temperature wear resistance of H13 steel with DBT can be improved significantly. Furthermore, the H13 steel with DBT assisted by ABSP possesses more superior wear resistance property at elevated temperatures than that of coarse-grained sample with DBT, which can be attributed to the fact that the thickness and microhardness of the borided layer can be increased with the help of ABSP. Meanwhile, the fatigue crack initiation and propagation in borided layer during the wear test can be impeded by the compressive residual stress and the refined grains in the borides of ABSP sample with DBT.

68