Paper Title
Effect of Fe-Intermetallics on the Hardness and Electrochemical Behaviour of Laser Deposited Sn-Zn Coatings on SAE-AISI 1010 Steel

Laser alloying of Sn–Zn coating on SAE-AISI 1010 steel was carried out using a 3-kW continuous wave (CW) Ytterbium Laser System (YLS) controlled by a KUKA robot which controls the movement of the nozzle head and emitting a Gaussian beam at 1064 nm. The corresponding microstructure, phase structure, microhardness profiles, and corrosion resistance performance of the laser-alloyed coatings were investigated. Microhardness test indicates that the laser-alloyed Sn-20Zn at 0.8 m/min coating has the highest microhardness. Also, corrosion resistance performance measurement in 3.65 wt.% NaCl reveals that the corrosion resistance of the laser-alloyed Zn-Sn coatings are much better than that of the substrate. Sample A1 at scanning speed of 0.6 m/min exhibited highest polarization resistance Rp (6813 Ω.cm2), lowest corrosion current density Icorr (1.54x10-6 A/cm2), lowest corrosion potential Ecorr (-1.0012 V) and lowest corrosion rate Cr (0.0179 mm/year) as compared to SAE-AISI 1010 steel. Increasing Sn content decreases the corrosion rate and increases the polarization resistance. Notable enhancement in corrosion resistance performance was achieved in Sn-Zn coatings. The microhardness of Sn-20Zn at scanning speed of 0.8 m/min is 1.4-times (42.59 %) than that of SAE-AISI 1010 steel (108 HV). The reaction between Fe and Sn induced a new microstructure which played a fundamental role in the hardness and corrosion properties.The intermetallic compound, FeSn2 acted as a barrier between the active steel substrate and the oxidizing environment, and significantly reduced the corrosion rate and enhance the hardness. The improved surface properties were attributed to major hard phases of iron-tin (FeSn2), and iron-zinc (Fe3Zn10). Keywords - SAE-AISI 1010 steel, Zn-Sn coatings, laser alloying, Corrosion resistance, microhardness, Fe