Search

AA2219 Al-Cu alloy is mainly used for aerospace and defence applications. Welding is used in the fabrication of components made of AA2219 aluminium alloy and causes microstructural changes in various zones that form during fusion welding of AA2219 alloy, which strongly influence the corrosion behaviour. Friction stir welding (FSW) could be the remedy to avoid the above problems and mainly joint strength of AA2219 FS welds gets affected by tool pin profile parameter. Mathematical models are developed using response surface method (RSM). A central composite design with four parameters and five levels has been used to limit the experimental conditions. Response optimisation shows the optimum combination of tensile strength, hardness and corrosion resistance were achieved with hexagon tool pin profile and welding parameters of rotational speed 1,214 rpm, welding speed 63 mm/min and axial force 11 KN. From the microstructural studies it was found that properties of the welds made with hexagonal tool pin profile are superior when compared to conical tool pin profile, and is attributed to relatively more fine grain structure in hexagonal tool pin profile when compared to conical tool pin profile.

Over the past decade, Dual Phase steels are extensively used in the automotive industry to reduce the weight of the vehicles. The Fiber laser welding has been showing superior weld quality over other laser welding methods. DP 600 grade is most widely used grade among DP steels. Influence of heat input on microstructural and mechanical properties for the given thickness has been investigated. Widths of weld zone and Heat Affected Zone have decreased with decreasing the heat input. Rapid cooling rates in the fusion zone have resulted in martensitic structure and hardness also increased in proportional. Tensile test and notch tensile test of the welded joints have been confirmed that weld joints are stronger than that the base material. From the ensile test along the weld joint of all heat inputs, it has been observed that lower heat input weld joints have shown better properties over the others.

In this present investigation, rotary friction welding has been used to join Ti64 rods. Different heat treatments namely α-β and β with stress-relieving (SR) were carried out before welding. After welding, corrosion studies were carried out in a 3.5% NaCl environment. It was observed that the α-β heat-treated condition with SR showed the least corrosion rate out of all conditions, whereas the β heat-treated condition has shown the highest. The primary reason for this is the microstructural changes due to heat treatment. Below β transus temperature led to the development of uniform α-β lamellar colonies around the primary α which provided good corrosion resistance in α-β heat-treated condition with SR. The above β transus heat treatment led to evolving fully lamellar structure which made the corrosion rate high. The optimized results indicate that the α-β followed by SR before welding has a better overall performance in corrosion resistance.