Effects of Laser Power on Microstructure and Corrosion Property of Laser Cladding FeCoNiCr High Entropy Alloy Coatings

The design of composition of high entropy alloy coatings fabricated by laser cladding has been explored by many scholars, but the influence of laser processing parameters on the structure and porpersity of the coating is still lack of systematic analysis. FeCoNiCr high entropy alloy coatings are fabricated on the surface of 316L stainless steel by laser cladding. The effects of laser power (1.2 similar to 2.0 kW) on the microstructure and corrosion resistance of FeCoNiCr coatings are investigated systematically. FeCoNiCr coatings fabricated with different laser powers have a typical single face centered cubic (FCC) structure, but with the increase of laser power, the coatings gradually show preferred orientation. FeCoNiCr coating presents typical double-layer structure, with columnar crystal at the bottom and equiaxed crystal at the top. However, with the increase of laser power, the equiaxed crystal at the top gradually changes to columnar crystal. Also, with the increase of laser power, the mixing entropy of FeCoNiCr coatings decreases gradually. The corrosion resistance of FeCoNiCr coating is good, but it gradually weakens with the increase of laser power. When the laser power is 1.2 kW, the self-corrosion current density of the coating reaches the lowest point and the self-corrosion voltage obtains its highest value. Moreover, there are no corrosion pits on the coating surface indicating that it has the best corrosion resistance, which is better than 316L stainless steel substrate and conventional laser cladding coatings such as Stellite6 and Ni60. The laser cladding of FeCoNiCr high entropy alloy coatings with good corrosion resistance is obtained by optimizing the laser power, which provides some theoretical guidance and technical supports for the development, preparation and application of this type of coatings.