Influence of rotational speed on interfacial microstructure and tensile properties of friction welded Al-SS pipe joints

Abstract

The present study focuses on friction welded joints between Al6063-T6 and SS304L pipes with different compositions that were examined to understand how rotational speed affected the evolution of the interfacial microstructure. A comprehensive study was done on the various microstructures, grain boundaries, kernel angle misorientation, and joint strength. Under the influence of rotational speed, there was a change in the metal flow, microstructures, and grain morphology at the welded area. However, the microstructure of Al6063-T6 altered from elongated to equiaxed grains due to dynamic recrystallization, and the grain size reformed from 2.10 to 2.63 μm, while SS grain size from 1.68 to 2.42 μm obtained with variation of the rotational speed. The distribution of grain misorientation angle at the interface was varied from 31 to 45° with the different rotational speeds. Al6063-T6 exhibited significantly greater misorientations and wider variances in their scattering compared to SS304L. The ongoing dynamic recrystallization was observed for the grain refinement on the Al6063-T6 side of the interface, whereas dynamic recovery was noted on the SS304L side. The texture intensity of Al6063-T6 and SS304L varies owing to the rotation speed. The various rotational speed plays a dominant role in the tensile strength and metallurgical bonding between Al6063-T6 and SS304L that causes a higher amount of elements to participate at the faying zone which leads to creating intermetallic compounds such as AlFe, FeAl₃, and AlFe₃ whereas the maximum strength of 214 MPa was received, which corresponds to 82% joint efficiency.