Diode area melting of Ti6Al4V using 808 nm laser sources and variable multi-beam profiles

Abstract

This paper presents an alternative to traditional laser powder bed fusion (LPBF), using an efficient, highly scalable multi-laser additive manufacturing methodology known as Diode Area Melting (DAM). DAM integrates multiple individually addressable low power fibre coupled diode lasers into a laser head, these traverse across a powder bed to melt powdered feedstock. The highly scalable and compact diode lasers operate at a shorter wavelength and lower powers compared to traditional LPBF fibre lasers, enabling a more efficient energy absorption, with an increase of up to 14%. In this study, a bespoke multi-laser head was used to process Ti6Al4V powder using ten 5 W 808 nm diode lasers simultaneously. Multi-layer parts were produced with a maximum density of 98% with variable beam profiles shown to greatly influence melt pool formation, microstructure and mechanical performance (4–5 GPa hardness and elastic moduli up to 120 GPa). DAM was able to generate lower cooling rates than traditional LPBF systems (600 °C/s compared to 107 °C/s), with variable beam profiles altering grain size and promoting the development of a β phase within components.

Keywords

• Additive manufacturing
• Laser powder bed fusion
• Multi-laser
• Microstructural control
• Laser absorption
• Ti6Al4V