Effect of La2O3 on granular bainite microstructure and wear resistance of hardfacing layer metal

The purpose of this work was to investigate the effect of La2O3 on the granular bainite microstructure and wear resistance of hardfacing layer metal. The hardfacing layer metals with different contents of La2O3 were prepared. The microstructures of the hardfacing layer metals were observed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The hardness and wear resistance of the hardfacing layer metals were measured respectively. The results indicated that with the increasing content of La2O3, the amount of granular bainite increased, while that of martensite decreased and that of retained austenite did not change obviously. When the content of La2O3 was 2.55 wt.%, the volume fraction of the granular bainite in the hardfacing layer metal was 73.2%. Meanwhile, the wear resistance of the hardfacing layer metal was the largest, which was 12100 min/g. The mismatch between the face (100) of LaAlO3 and the face (100) of δ-Fe was 7.1%. Therefore, LaAlO3 could act as moderate effective heterogeneous nuclei of δ-Fe and the granular bainite could be refined.