Mechanical and corrosion behaviours of dual-phase steels welded by fcaw in 3.5% NaCl solution

The aim of this study is to demonstrate the transformation of Grade A steel into dual-phase steel by heat-treatment at the chosen 730°C and 800°C intercritical temperatures for 60 min followed by cold water quenching and the corrosion behaviour in 3.5% NaCl solution of Grade-A and dual-phase steels welded by flux-cored arc welding (FCAW). It has been investigated microstructure properties, microhardness and tensile test. It was carried out the mass loss measurements and investigated the macrostructure using by optical microscope.The experimental results revealed that the tensile strength of the dual-phase steels is higher than that of the Grade-A steel. The microstructure investigation shows that while the microstructure of Grade-A steel consists of ferrite and pearlite phases, the microstructure of the dual-phase steels consists of ferrite and martensite phases. The results from the immersion test showed that the mass loss of the dual-phase steel is lower than that of the Grade-A steel. Dual-phase steels with or without welded have been the mass loss rate immersed in 3.5% NaCl solution. The corrosion has preferential started at fusion line and progressed towards the heat affected zone (HAZ) of the welded dual-phase steels.