Effect of Grade 5 titanium interlayer on microstructure and pitting corrosion behaviour of AA1100/A36 explosion welds

Abstract

Explosion welding is a solid-state welding process that is used for the metallurgical joining of similar and dissimilar combinations of metals and alloys with varying physical and mechanical properties. In this process the metal surfaces are brought into sufficiently close contact, the valence electrons overcome the repulsive forces and result in sharing of their orbits. In recent years ocean acidification is the main problem due to a variety of pollutants. In naval applications A36 steel is used for making ship hulls that are very poor in corrosion. The present study is aimed to improve the corrosion resistance of the A36 steel by cladding aluminium alloy (AA110) using the explosion welding technique. Grade 5 titanium alloy has been used as an inter-layer between AA110 and A36 plates. The presence of Ti-6Al-4V inter-layer facilitated good bonding between aluminium and steel dissimilar weld joint with smooth bond line. The microhardness values were measured at various points start from the weld interface and towards both base metal regions. Higher hardness values were observed in the bond region and the Inter-layer regions, owing to the inherent higher hardness of Titanium and the formation of Martensitic structure near the bond region, as a result of higher and sudden impact energies. Potentiodynamic polarization tests were made in 3.5% NaCl solution. Corrosion resistance in AA1100 is higher than A36. All the observed results were correlated with microstructural features as evidenced by SEM studies.