Effect of Laser Power on Microstructure and Tribological Performance of Laser Cladded Ni-60%WC Coating on H13 Steel
Y. Ge, C-Y. Zheng, L-J. Dai, C. Liu and D-J. Kong
Ni-60%WC coatings were deposited on H13 steel substrate by laser cladding with a fibre laser. The microstructure, microhardness and wear performance of the obtained laser cladded Ni-60%WC coatings and the effect of laser power on the coefficient of friction (COF) and wear rates were analyzed. The results show that the microstructure of laser cladded Ni-60%WC coatings is mainly composed of WC and γ-Ni solid solution phases, and the hardness is decreased with an increase in laser power. The average COFs of laser cladded Ni-60%WC coatings deposited at laser power of 2100, 2500 and 2900 W are 0.51, 0.52 and 0.53, respectively; and the corresponding wear rates are 40.40 × 10-6, 86.20 × 10-6 and 120.25 × 10-6 mm3/Nm, respectively. From this it can be said that the laser power of 2100 W presents as the optimum in terms of wear resistance. The WC hard phase in the laser cladded Ni-60%WC coatings reduces the plastic deformation caused by the tribo-pair, and the wear mechanism is dominated by abrasive wear, accompanied with adhesive wear.
Keywords: Fibre laser, Ni-60%WC, H13 steel, laser cladding, laser power, microstructure, coefficient of friction (COF), hardness, wear rate