High-speed laser cladding of chromium carbide reinforced Ni-based coatings

Fusion-bonded and low-diluted overlay welded coatings are frequently very thick (>1mm). High-speed laser cladding is a novel process capable of producing thin fusion-bonded and low-diluted coatings with high coverage rates and low heat input. In this study, for the first time, high-speed laser cladding was used to fabricate relatively thin Ni-based coatings reinforced with chromium carbides onto low-alloy structural and quenched and tempered steels. Obtained coatings were characterized with X-ray diffraction (XRD), optical (OM), and scanning electron microscopy (SEM), as well as electron backscatter diffraction (EBSD). Mechanical and wear properties were tested with Vickers microhardness measurements and three-body dry-sand rubber wheel abrasion tests (RWAT). It was shown that high-speed laser cladding produces 0.2-0.3 mm thick coatings, which consist of ultrafine-substructured hypereutectic M7C3 structures reinforced with coarser primary Cr3C2 particles. Coatings with hardness up to 1300 HV0.05 exhibited high wear resistance in low-stress three-body abrasion. Coatings developed can be used as alternatives for hard-chrome plated coatings.