The effect of B4C on wear behavior of stellite6 matrix composite clad layer fabricated by GTAW

A composite clad layer of stellite6 matrix was fabricated on plain steel and the effect of B4C reinforcing particles on microstructure characteristics, hardness and wear behavior was investigated. For this purpose B4C powder with different weight percentages were pasted on substrates and subsequently melted by GTAW using stellite6 filler. Microstructural investigations of clad layers were conducted by optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy dispersive spectrometery (EDS). X-ray diffractometery (XRD) was used for structural evaluation of clad layers. Hardness and wear behavior were studied by microhardness testing and pin on disk wear test, respectively. The results showed that the clad layer mostly contain  cobalt-rich matrix, eutectic carbides such as Cr7C3 and Cr23C6 relating to the matrix and secondary phases such as CoB2, CrB2, WC and W2B resulted from the reaction of B and C with other elements after decomposition of B4C. By the addition of B4C content in the clad layer a finer dendritic structure with more interdendritic phases was obtained. Moreover, composite clad layers exhibited higher hardness compared to stellite6 clad layer. Wear mechanism of stellite6/B4C composite clad layers was delamination and the stellite-20 wt.% B4C showed the least wear rate.