The metallurgical implications of laser forming Ti-6Al-4V sheet

Abstract

In recent years, laser forming (LF) has developed into a promising technique for sheet metal forming, rapid prototyping and dimensional correction in the aerospace industry. In this work, the effect of the very high heating and cooling rates experienced during LF on the metallurgical properties of a Ti-6Al-4V alloy were investigated. Optical microscopy, FEGSEM and TEM were used to establish the phase morphology, size and elemental distribution within the laser affected region, or heat affected zone (HAZ). It was found that the microstructure produced during LF is extremely complicated with the phase morphology and phase distribution varying throughout the HAZ. Microhardness tests have shown a progressive increase in hardness on approaching the surface incident to the laser beam, associated with the formation of a martensitic phase. The metallurgical evolution during post-forming heat treatment of the LF samples was also investigated. In addition tests have been performed to establish the influence of the HAZ on strain localisation during tensile deformation and the mechanical properties of laser formed sheets.In recent years, laser forming (LF) has developed into a promising technique for sheet metal forming, rapid prototyping and dimensional correction in the aerospace industry. In this work, the effect of the very high heating and cooling rates experienced during LF on the metallurgical properties of a Ti-6Al-4V alloy were investigated. Optical microscopy, FEGSEM and TEM were used to establish the phase morphology, size and elemental distribution within the laser affected region, or heat affected zone (HAZ). It was found that the microstructure produced during LF is extremely complicated with the phase morphology and phase distribution varying throughout the HAZ. Microhardness tests have shown a progressive increase in hardness on approaching the surface incident to the laser beam, associated with the formation of a martensitic phase. The metallurgical evolution during post-forming heat treatment of the LF samples was also investigated. In addition tests have been performed to establish the influence of the ...