Electrochemical Studies on the Corrosion Behaviour of Laser Alloyed Zn-Sn Coatings on UNS G10150 Steel in 1M HCl Solution

Surface deterioration by corrosion is one of the complications associated with ageing facilities and components especially under some service environments. This study was designed to investigate the enhancement in the corrosion and hardness properties of UNS G10150 steel laser alloyed with three different premixed compositions of Zn-Sn binary powders using a 4.4 KW continuous wave (CW) Rofin Sinar Nd:YAG laser processing system. The steel alloyed samples were cut to corrosion coupons, immersed in hydrochloric acid (1M HCl) solution at 30 ^°C using an electrochemical technique and investigated for their corrosion behaviour. The morphologies and microstructures of the developed coatings and uncoated samples were characterized by an Optic Nikon Optical microscope (OPM) and a scanning electron microscope (SEM/EDS). Moreover, a X-ray diffractometer (XRD) was used to identify the phases present. An improvement of 2.5-times the hardness of the steel substrate was achieved in A₁(0.8) which may be attributed to the fine microstructure, dislocations and the high degree of saturation of solid solution brought by the high scanning speed. At a scanning speed of 0.8 m/min, sample A₁ exhibited the highest polarization resistance R_p (3163000 O.cm²), lowest corrosion current density i_corr (7.95X10^-8A/cm²), with a lowest corrosion rate Cr (0.000924 mm/year) in 1M HCl solution. The polarization resistance R_p (3163000 O.cm²) is 392,281-times the polarization of the UNS G10150 steel substrate with a 99.9994 % reduction in the corrosion rate.