Investigation of Mechanical Properties of Friction and Laser Welded Ti-6Al-4V rods

Abstract

Understanding the mechanical properties of welded regions is an imperative practice as it leads to safer designs with improved quality. This paper presents the evaluation of the mechanical properties of rotary friction and laser-welded Ti-6Al-4V alloy rods. It a comparative study of the welds produced by the respective techniques. Rotary friction welding was performed at varying speeds while other parameters were kept constant. A continuous Ytterbium fiber laser was used at varying welding speeds and laser power. The weld joints were evaluated by performing tensile testing, microhardness, metallography, and fractography. Friction welds demonstrated superior strengths that are higher than the parent material (PM) with all specimens failing at the parent material, while the laser welds demonstrated superior hardness with brittle fractures at the weld interfaces. A refined lamellar microstructure was observed on the friction weld with equiaxed α and β grains. Laser welds demonstrated coarse columnar grains with a martensitic structure and a presence of voids. The heat affected zone (HAZ) in laser welded specimens increased in size with the interaction time and were wider compared to the friction welded specimen which demonstrated dynamic radial deformation with little microstructural distinction from the parent material.