Microstructure, wear, and compressive behaviour of laser cladded hybrid TiC-SiC reinforced 16MnCr5 composites

Hybrid reinforcement composite coatings have enormous potential in improving the wear resistance and mechanical properties of components subjected to high-loading conditions. This study explored the synergic effect of TiC (20 wt% to 40 wt%) and SiC (0 to 20 wt%) contents on the geometry, phase evolution, microstructure, microhardness, wear, and compressive behaviour of 16MnCr5-TiC-SiC ternary composite coatings on A514 steel substrate. The dominant phases observed in the coatings are α-Fe, TiC, Fe_xSi_y, Fe₃C, and M₇C₃. As the content of SiC increases, Fe₃C and M₇C₃ phases gradually disappear due to the stabilisation of the Fe with Si. The microhardness of the coatings was substantially enhanced, with the average matrix microhardness varying between 778.6 ± 73 HV_0.3 to 1003.3 ± 47 HV_0.3, compared to the substrate (214.5 ± 9 HV_0.3), which constitutes an increase of 263 % to 368 %. The wear resistance properties of all the coatings exhibited an improvement varying between 2.5 and 6.7 times over that of the substrate, with 5 wt% SiC/35 wt% TiC coating achieving the highest wear resistance. The high SiC content compromised the coatings' microhardness and wear resistance due to its high dissociation and subsequent graphite precipitation in the Fe alloys. Furthermore, the compressive strength of the coating with 5 % SiC was the highest (1128.2 ± 21 MPa), surpassing that of the substrate (992.4 ± 67 MPa) by 14 %. In contrast, the lowest compressive strength (525.2 ± 58 MPa) occurred in the coating with 0 % SiC due to the high volume proportion of retained carbides in the matrix, which detach from the matrix under stress, leading to deformation.