Improved Zn-based coatings for ipersandelin steel products

The protection of iron-based alloy products against corrosion is fundamental to preserve their mechanical properties in aggressive environments. Hot-dip galvanizing process represents one of the most used techniques to make protective coatings for such products [1,2] . In order to improve both mechanical and chemical properties of coating, metallic elements may be added to the traditional zinc bath [3-5] . In the present paper, two types of improved zinc-based coating are proposed : (i) a coating obtained employing a tin addition (3% in weight); (ii) a coating obtained employing aluminium (5% in weight), tin (1% in weight) and copper (0.5% in weight) additions. Firstly, the performance of such two coatings is experimentally investigated through bending tests on ipersandelin steel plate specimens, treated by adopting different dipping times. The intermetallic phase thicknesses of coatings are measured for each dipping time, in order to evaluate the kinetic formation. Then, a Finite Element (FE) model is proposed in order to simulate the bending behaviour of the above specimens, both employing the measured phase thickness and implementing the loading and boundary conditions of the experimental tests. A numerical non-linear static analysis is performed. A quite satisfactory agreement between experimental and numerical results is noticed, especially under plastic behaviour regime. REFERENCES [1] Marder A.R. (2000). Metallurgy of zinc-coated steel, Progress in Materials Science 45, 191-271. [2] Carpio J., Casado J.A., Alvarez J.A., Mendez D., Gutierrez-Solana F. (2010). Stress corrosion cracking of structural steels immersed in hot-dip galvanizing baths, Engineering Failure Analysis 17 , 19–27. [3] Di Cocco V. (2012). Sn and Ti influences on intermetallic phasesdamage in hot dip galvanizing, Frattura ed Integrita Strutturale 22 , 31-38. [4] Di Cocco V., Iacoviello F., Natali S. (2014). Damaging micromechanisms in hot-dip galvanizing Zn based coatings, Theoretical and Applied Fracture Mechanics 70 , 91-98. [5] Natali S., Volpe V., Zortea L., Burattini C., Di Cocco V., Iacoviello F. (2015). Mechanical and Structural Characterization of Zn-Ti Colored Coatings, Procedia Engineering 109 , 105-112.