On the performance of metallurgical behaviour of Stellite 6 cladding deposited on SS316L substrate with PTAW process

Cobalt rich Stellite 6 cladding shows a superior result against wear, corrosion and galling. However, the metallurgical bonding at the cladding interface, if not achieved carefully, may result in failure during service. Hence, the proposed Stellite 6 weld overlay is deposited by plasma transferred arc welding (PTAW) process on SS316L substrate. Mechanical characterisation of this combination has been already attempted earlier with the help of a fine-tuned welding parameters. The same work has been reconsidered in the present research study for its detailed metallurgical investigation. In order to investigate the metallurgical variation at the interface, two samples with different weld parameters (sample A and B) have been considered. Cobalt rich phases have been obtained in both samples such as γ-Co (FCC), ϵ-Co (HCP), CrCo along with different carbides of chromium and tungsten such as Cr7C3, Cr23C6, W6C which are confirmed by EDS and XRD analysis. The formation of different phases shows the W6C, interdendritic eutectic phases Cr7C3, Cr23C6 and primary dendritic phases γ-Co, ϵ-Co and CrCo that are chiefly responsible for the higher hardness of sample B which has lower heat input.