Effect of high-temperature heat treatment on electrochemical corrosion behavior of laser cladding Fe-based alloy coating in H2SO4 solution

Abstract

Double-layer Fe-based alloy coatings were fabricated on the surface of ductile cast iron using high-speed laser cladding. The electrochemical corrosion behavior of the coatings in 0.5 mol/L H2SO4 solution was analyzed after heat treatment (HT) at 950 ℃ for 1, 2, and 3 h. The results show that many fine and dispersed particles were precipitated in dendrites after 1 and 2 h HT. The precipitates in the dendrites of the 3 h heat-treated aggregated, nucleated, and grew up, forming the blocky. At the same time, the intergranular part of the long-chain structure began to dissolve and break. The corrosion rate decreased significantly with the increase in HT time. The specimen had the most-nobel self-corrosion potential (−0.15 V) and the best corrosion resistance after 3 h HT.