Microstructure And Properties Of WC-Co Composite Hastelloy C276 Laser Melting Deposition

Hastelloy C276 has been widely used in petrochemical,aerospace,marine and nuclear industries due to its excellent corrosion resistance and good mechanical properties.This paper fabricated multi-layer bulk samples of Hastelloy C276 as well as WC-Co enhanced Hastelloy C276 composite coatings by laser melting deposition.The mechanical tensile properties and fracture morphology of Hastelloy C276 were studied,and a constitutive model was established to predict the tensile behavior.The effects of WC-Co particles on the microstructure,hardness,friction and wear behavior and electrochemical corrosion behavior of C276 alloy were studied.The main research contents and results can be drawn as following:(1)Through experiments and numerical simulation methods,the powder transportation characteristics of the coaxial powder feeding nozzle are studied.single-channel coatings of Hastelloy C276 was fabricated,and the influence of process parameters such as powder feed rate,gas flow rate,laser power and scanning speed on the quality of the coatings was studied.The best process parameters were determined by quality evaluation indicators such as the height,the width of the coatings and the dilution rate.Using the best process parameters(gas flow rate5L/min,powder delivery rate 1.5r/min,laser power 800 W,scanning speed 10mm/s,and overlap rate 50%),C276/WC-Co composite coatings were prepared with different proportions(0wt.%,10 wt.%,15 wt.% and 20 wt.%)of WC-Co particles.In addition,multi-layer bulk samples of Hastelloy C276 with a size of 60mm×80mm×11mm was prepared.(2)The microstructure,hardness,mechanical tensile properties of Hastelloy C276 bulk samples perpendicular to the laser scanning direction and parallel to the laser scanning direction are studied.The results show that the tensile strength and yield strength of Hastelloy C276 prepared by laser melting deposition are higher than the international standard,and the elongation is lower than the international standard.In addition,a J-C constitutive model of Hastelloy C276 was established to predict the tensile behavior of the material,and the simulation results was consistent with experimental results.(3)The microstructure,hardness,friction and wear performance and electrochemical corrosion performance of C276/WC-Co composite deposited coating were studied.The results show that most of the WC-Co particles are evenly distributed in the coating and provide favorable conditions for heterogeneous nucleation.The microstructure of C276/WC-Co composite coatings are composed of?-Ni solid solution dendrites and interdendritic Mo Ni solid solution eutectic.After adding WC-Co particles,the hardness and wear resistance of C276 alloy are significantly improved,but the electrochemical corrosion performance is slightly decreased.