Effects of rapid solidification on the microstructure and surface analyses of laser-deposited Al-Sn coatings on AISI 1015 steel

Corrosion and wear phenomenon has been responsible for the gradual deterioration of components in industrial plants. This deterioration of components results in loss of plant efficiency, total shutdown and aggressive damage in a number of industries. Hence, surface modification and coating technique with enhanced surface properties is desirable. The study was designed to investigate the enhancement in the corrosion, hardness and wear properties of Al-Sn binary coatings on AISI 1015 steel by laser alloying technique using ytterbium laser system (YLS). A laser power of 1000 W, scanning speeds of 0.6 and 0.8 m/min, and alloy compositions of Al-75Sn, Al-50Sn and Al-25Sn were used in this study. Decrease in Sn content from 75 to 25% at different laser processing conditions resulted in improved properties. The enhanced properties were obtained at 75Al-25Sn alloy at laser power of 1000 W and speeds of 0.6 and 0.8 m/min. At optimum composition and speed of 0.8 m/min, there was enhancement of 53.63% in microhardness. At scanning speed of 0.6 m/min, 75Al-25Sn alloy exhibited the highest polarization resistance, R (p), (1.06 x 10(8) Omega cm(2)); lowest corrosion current density, I (corr), (3.12 x 10(-7) A/cm(2)); and lowest corrosion rate, C (r), (0.00363 mm/year) in 3.65 wt% NaCl solution. In addendum, significant reduction in wear volume loss of 75Al-25Sn alloy at 0.8 m/min was attributed to excellent wear resistance performance due to metastable intermetallic phases. This research has established the enhanced surface properties of laser alloyed Al-Sn binary coatings on AISI steel for engineering applications.