Microstructure and thermal physical parameters of Ni60-Cr3C2 composite coating by laser cladding

To satisfy performance and long life requirements for hot forging die, Ni60-Cr3C2 composite coatings were prepared on the high-speed steel W6Mo5Cr4V2 using laser cladding technology. Laser clad coatings with different ratios of Ni60:Cr3C2 were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX) and microhardness tester, respectively. Specific heat capacity and thermal conductivity were measured by Laser Thermal Constant Meter. Thermal expansion coefficient and elastic modulus were measured by Dynamic Mechanical Thermal Analyzer and Electro-Hydraulic Servocontrolled Testing System, respectively. The results indicated that Ni60+50wt% Cr3C2 composite coating had dense and homogeneous structure, as well as a metallurgical bonding with the substrate. With the increase of Cr3C2 content, volume of chromium-containing compounds in the composite coating increased, microhardness increased and microstructure refined. The thermal physical parameters results showed that Ni60+ 50wt% Cr3C2 composite coating was overall worse than W6Mo5Cr4V2, but had a higher hot yield strength to alleviate hot fatigue and surface hot wear of hot forging die during hot forging and thus improve the service life of hot forging die.