Examining the Mechanical and Tribological Characteristics of Lamellar Carbide in the Laser-Clad Stellite-6 Coating Applied to a Steel Substrate

Abstract In this study, Stellite-6 was deposited onto 316L steel using the laser cladding process. The defect-free 500 μm thickness of Stellite-6 coating was achieved on the steel substrate. The X-ray diffraction revealed the presence of chromium carbide along with a cobalt-rich region in the Stellite-6 cladding region. Throughout the laser-processed region, the orientation of the nanoscale lamellar carbide (Cr7C3) exhibited notable variability, which is pivotal to its mechanical properties. A nanohardness test at 50 points with a load of 7500 μN showed values ranging from 6.77 to 9.64 GPa within the lamellar carbide (Cr7C3) region, reflecting the differences in lamellar structure orientation. Similar studies were carried out on the nanowear surface, maintained under the same load conditions. The geometry of the indenter is Berkovich. The speed and number of cycles were 0.277 and 3 μm/s, respectively. The number of data points collected in the test to draw the wear depth curve was 27.600. It revealed that the non-parallel orientations of the lamellar carbide (Cr7C3) not only displayed higher nanohardness but also resulted in reduced wear depth, compared to regions with parallel orientation. In the non-parallel orientations, the force transferred from one lamellar strip to the next was reduced by the sin(θ) value since sin(θ) is less than 1 for angles between 0° and 90°. As a result, the force transferred to the last lamellar carbide (Cr7C3) strip was significantly lower. Therefore, the force at the last lamellar carbide (Cr7C3) strip in the non-parallel orientations were less than that in the parallel orientation. Intriguing phenomena were observed in the simulated annealing surface, including lattice formations, material pile-up, and domain structures in both the nanohardness and nanowear track regions. Notable contrasts were identified between cobalt-rich areas and lamellar carbide.