Composition Design,Laser Fabrication And Corrosion Behavior Of FeNiCrAl Alloy Coating

Aimed at stainless steel surface modification, a FeNiCrAl coating alloyed by content the addition of different element Al were fabricated on the 304 stainless steel substrate by laser cladding. The clad layers without pores and cracks were obtained, and an excellent bonding between the clad layers and the substrate was ensued by a strong metallurgical interface. The microstructure of clad layers was characterized using XRD, SEM and EPMA . Microhardness of clad layers was measured through HVS-1000 type microhardness tester.Phases of laser cladding coatings through preplacing FeNiCrAl alloy on 304 stainless steel substrate were composed ofγ-Fe solid solution.As different content of Al, the coating have FeAl and Fe₃Al. The microhardness distribution curve of clad layers was composed of three parts: clad layer of the tallest value, heat-affected zone of medium value and substrate of the lowest value. The average microhardness of coating was 230 HV, which was 1.8 times of the substrate.Corrosion resistance and mechanisms of these alloys were researched through erosion and electrochemical corrosion. Erosion test of alloys was performed in the solutions of mixtural acid (10%HCl +10%HNO₃) and 6% FeCl₃, experimentation temperature was 90℃.Made corrosion behaviour analyse and grade assess of sample. The results show that alloy coating corrosion resistance was superior to the substrate.The anodic polarization curves in different electrolyte solutions were measured by the experiments of electrochemical corrosion. The actions of all elements in alloy were analyzed by discovering the changes of corrosion potentials, corrosion current density, passivation potentials, passivation retaining current density and slope of Tafel reciprocal in different of alloys and in different electrolyte solutions. The results show that alloy coating corrosion resistance and pitting resistance was better than the substrate at sulphuric acid and 3.5%NaCl solution,and content of 2.5% Al alloy coating corrosion resistance and pitting resistance was best of all.