Effects of laser energy density on microstructure and corrosion resistance of FeCrNiMnAl high entropy alloy coating

In this work, FeCrNiMnAl high entropy alloy (HEA) coating was successfully prepared by laser cladding technology on 17-4PH stainless steel substrate. The aim of the study was to investigate the effects of laser energy density (Led = 50 ∼ 70 J/mm2) on the geometric characteristics, microstructure and corrosion resistance of HEA coatings. The results indicated that Led would significantly affect the Geometrical characteristics of the coatings, and the height, depth and width increased with increasing laser energy density. In electrochemical tests, the corrosion resistance of coatings tended to increase and then decreased with increasing Led. At the Led of 65 J/mm2, the corrosion current density of the coating was only 1.156 × 10-5 A/cm2, indicating that the dense passive film was formed on the surface of HEA coating. The corrosion resistance of the coating was closely related to the passivation film on the surface of the coating. At the Led of 50 J/mm2, microcracks on the coating surface could facilitate ionic intrusion, resulting in poor corrosion resistance. However, at the Led of 65 J/mm2, the corrosion products on the coating surface were less and the corrosion resistance was optimum. Accordingly, the laser cladding process had a significant impact on the quality and performance of HEA coating. Modulation of laser process parameters was an effective method to optimize coating performance.