Study on corrosion behavior of TWIP steel and properties of surface electroless Ni-P coatings

In this study, the corrosion behavior and corrosion resistance of TWIP (Twinning Induced Plasticity) steels in the industrial atmospheric environment were studied by dry-wet cycle immersion test and electrochemical experiments. The results showed that the corrosion rates of TWIP steel gradually decreased with the increase of corrosion time. A layer of corrosion products was formed on the surface of TWIP steel during alternating immersion accelerated corrosion process, whose main components were Fe₃O₄ and α-FeOOH. With the prolongation of corrosion time, the rust layer on the surface of TWIP steel had a certain protective effect on the steel matrix. The adherent and defect-free electroless nickel–phosphorus (Ni-P) coatings were prepared on TWIP steels. Electrochemical test results showed the corrosion current density of the coating was about six times lower than that of TWIP steel substrate, indicating that the coating effectively improved corrosion resistance of TWIP steel and protected the steel substrate from erosion of corrosive ions. Additionally, the surface microhardness of TWIP steel was significantly increased after electroless Ni-P plating treatment. (paper)