Experimental study of hardness values and corrosion behaviour of laser alloyed Zn-Sn-Ti coatings of UNS G10150 mild steel

Abstract

Coatings obtained from Zn-Sn bath are characterized by the traditional phases, whereas presence of Ti leads to coatings constituted by phase in the inner layers, and by an outer layer made of three phases and intermetallic phases which made the materials to be brittle. In order to enhance the properties of Zn-Sn-Ti coating of mild steel lead to the investigation of Zn-Sn-Ti coating on the mild steel by laser method. The performance evaluation was systematically observed and a homogeneous and coherent surface morphology was maintained. The laser power of 750 and 900 W, scanning speed of 0.6 and 0.8 m/min, alloy composition of 25%Zn-25%Sn-50%Ti and 20%Zn-20%Sn-60%Ti were used in the research. The laser alloy of Zn-Sn-Ti on the UNS G10150 steel showed better hardness values and corrosion resistance compared to substrate. All the properties improve by increasing the Ti content in the alloy from 50 to 60%. Laser power and scanning speed have great influences on the corrosion behaviour and morphology of the mild steel. An improvement of 6.9times the hardness of the steel substrate was achieved at 20%Zn-20%Sn-60%Ti-0.8 compared to the substrate. The corrosion rate of 0.06100 mm/year and 3.95E-05 mm/year were obtained for the 25%Zn-25%Sn-50%Ti and 20%Zn-20%Sn-60%Ti at 750 and 900w with a speed of 0.8 m/min respectively. The optimum properties was obtained at 20%Zn-20%Sn-60%Ti at laser power of 900 W and speed of 0.8 m/min. It have been established that laser alloy of Zn-Sn-Ti on UNS G10150 steel can be used in improving the surface hardness values and corrosion resistance.