Electrochemical behaviour study of laser deposited titanium‐tin coatings on ASTM A29 steel in saline environment

Abstract

AbstractLaser alloying of titanium–tin coating on ASTM A29 steel was carried out using a 3‐kW continuous wave ytterbium laser system 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 properties of the laser‐alloyed coatings were investigated, and the coatings were homogenous and free of cracks. Microhardness test indicates that the laser‐alloyed Ti‐50Sn at 0.8 m/min coating has the highest microhardness. Also, corrosion resistance performance measurement in 3.65 wt.% saline environment reveals that the corrosion resistance of the laser‐alloyed titanium‐tin coatings are much better than that of the ASTM A29 steel. At scanning speed of 0.8 m/min, sample B1 exhibited the highest polarization resistance Rp (23323 Ω⋅cm2), lowest corrosion current density Icorr (1.93⋅10‐6 A/cm2), and lowest corrosion rate Cr (0.0225 mm/a) in saline environment. The polarization resistance Rp (23323 Ω⋅cm2) is 1785.4 mm/a‐times the polarization of the ASTM A29 steel substrate. The microhardness of Ti‐50Sn at scanning speed of 0.8 m/min is 2.4‐times (57.86 %) than that of ASTM A29 steel (118 HV0.1). The microhardness increases with decreasing tin content in the titanium matrix. The improved surface properties were attributed to major hard phases of iron‐tin (FeSn2), and iron‐tin‐titanium (FeSnTi).