Tensile properties and fracture behavior of laser cladded WC/Ni composite coatings with different contents of WC particle studied by in-situ tensile testing

The aim of this paper was to address the effect of WC content on the tensile properties of WC/Ni composite coatings deposited by laser cladding on 45# steel substrates. The tensile tests were performed in the chamber of a scanning electron microscope. Experimental results showed that the mechanical properties and fracture behavior of WC/Ni coatings were strongly dependent on the volume fraction of WC reinforcing particles in the coatings. The tensile properties of the coating decreased with increasing content of WC particle. When the WC content was relatively high, multiple through-width cracks (TWC) in the coating can be found. The number of through-width cracks in the coating as a function of applied strain was measured. From the in-situ observation of coating surfaces, most of cracks were initiated from the WC particle, and then propagated throughout the coatings. This phenomenon was attributed to the stress concentration in the WC particle or near the WC particle, which was confirmed by using finite element analysis. The present research may provide some insights on the development of designing methodology of composite coatings.