Microstructural Evolution during Laser Processing of Titanium Alloy

Abstract

Abstract. The laser beam forming (LBF) process is a unique manufacturing process that has the potential to revolutionise rapid prototyping in the automotive and the aerospace industries. Traditionally, these industries require expensive tooling (stamping dies and presses) to form parts from sheet metal to develop prototypes for testing and evaluation. However, LBF offers an affordable non-contact and flexible rapid prototyping method for most of the manufacturing the industries. Despite these unique benefits, it is important to investigate the evolved microstructure because LBF employs high laser density to induce thermal stresses in the material to create the desired deformation. The study examines the microstructural development during laser beam processing of Ti-6Al-4V alloy sheets. The Ti-6Al-4V sheets were successfully processed at two different parameters of 800 W and 1000 W, and further microstructurally characterised through the optical microscopy. The results show that the micrograph of the parent material consists of a mixture of equiaxed and acicular alpha and beta-phases which are typical of Ti-6Al-4V. The micrograph of the sample formed at 800 W shows structures of globular particles of beta-phase in the alpha-phase matrix with an average grain size of about 12 µm. Also, there was a presence of bands of martensitic structure on the micrograph as a result of the heating from the laser beam. Similarly, the samples processed at 1000 W shown in the micrograph an alpha -phase and apha+beta-phase with an average grain size of about 8 µm with traces of martensites.