Adam M. Philo
Swansea University, UK
Title: The crucible method: A new technique of generating process maps for laser powder-bed fusion
Biography
Biography: Adam M. Philo
Abstract
Laser powder-bed fusion (LPBF) is an additive manufacturing process fusing metal powder layer-by-layer to form complex 3D components. LPBF is seen as a rapid evolution of machine design (more and higher power lasers, improved laser control and build preparation software) giving increased density of built parts, better inter- and intra-build repeatability, all leading to better mechanical properties. The traditional method to create process maps via post-mortem examination of solidified single line tracks aims to understand how the laser interacts with the powder to form single line tracks directly onto a baseplate. Control of process parameters such as speed, power and beam diameter are integral to choosing optimal laser penetration whilst avoiding evaporation, keyhole melting or balling defects. This method is limited as the substrate may be of a similar composition but microstructurally dissimilar and controlling additional parameters such as the powder layer thickness is difficult. A new crucible method is described and compared to the traditional method using Ti-6Al-4V and 316L with advantages, which include: i) high-throughput, high-quality topographical and cross-sectional metallography to be easily obtained. ii) tracks to be built in-situ on a previously deposited substrate is more representative of the process at all layers. iii) tight control on the powder depth and additional parameters. The crucible method predicted a much less severe transition between conductive and keyhole modes of melting than direct deposition of single tracks onto a baseplate, with shallower re-melting of lower layers. The crucible method also predicted a more forgiving transition between continuous and discontinuous tracks.