This study investigated the effect of cladding on tool steel (SKD61) by using 5%Cr-1.5%Mo-Fe powder (SKD61), which is expected to be economically effective when used to manufacture and mend die-casting parts. The cladding conditions were as follows: the distance between the coaxial powder supply head and the substrate surface was 20 mm, and Ar was used as the supply gas. The laser outputs applied in the cladding procedure were 3, 4, and 5 kW. The microstructure of the heat-affected zone in the processed specimens was analyzed, and the macrostructure and morphology of the substrate material were studied. Specimen hardness measurements were performed at intervals of 0.1 mm from the substrate surface to the core. As the laser output increased from 3 to 4 and 5 kW, the dilution rate increased from 10.6% to 11.8 and 13.2%. It was confirmed that the fraction of carbides increased as the laser output increased from 3 kW to 5 kW.

In this study, a novel composite was fabricated by adding the Hafnium diboride (HfB2) to conventional WC-Co cemented carbides to enhance the high-temperature properties while retaining the intrinsic high hardness. Using spark plasma sintering, high density (up to 99.4%) WC-6Co-(1, 2.5, 4, and 5.5 wt. %) HfB2 composites were consolidated at 1300℃ (100℃/min) under 60 MPa pressure. The microstructural evolution, oxidation layer, and phase constitution of WC-Co-HfB2 were investigated in the distribution of WC grain and solid solution phases by X-ray diffraction and FE-SEM. The WC-Co-HfB2 composite exhibited improved mechanical properties (approximately 2,180.7 kg/mm2) than those of conventional WC-Co cemented carbides. The high strength of the fabricated composites was caused by the fine-grade HfB2 precipitate and the solid solution, which enabled the tailoring of mechanical properties.