We report on the use of a pulsed Nd:YAG laser and optical fibres to produce WC/Ni clad layers on H13 tool steel substrates. The effects of laser parameters, such as laser pulse energy, pulse length and pulse frequency as well as material parameters such as powder composition on the clad layer microstructure and wear properties were investigated. The microhardness of the clad layers was measured using a Vickers microhardness tester. The microstructure of the clad layers was assessed by optical and scanning electron microscopy in conjunction with x-ray diffraction.
The results show that up to 1 mm thick, fully dense and crack-free clad layers of WC/Ni can be formed in a single pass with an incident average laser power of 440 W delivered through a 600 μm diameter, glass fibre. The results further show that the higher the microhardness of the clad layer, the higher its wear resistance. Average surface microhardness values of the coatings were as high as 650 HV0.5 and, in low stress abrasion tests, their abrasive wear resistance was up to 10 times higher than that of heat-treated H13 tool steel.