Fast in situ synchrotron imaging of laser additive manufacturing

Abstract

Laser powder bed additive manufacturing (LAM) promises to produce unique, high quality components for aerospace to biomedical applications. However, the mechanisms controlling the formation of continuous, defect free, track are still poorly understood. The cooling rates are far from equilibrium causing solidification defects (porosity, epitaxial growth) and high residual stresses. Using fast synchrotron X-ray imaging and a bespoke LAM process replicator (LAMPR), we present a step change in the methodology used to characterise and optimise the process. We apply the LAMPR over a range of laser velocities and powers, developing a mechanism map to predicting the processing conditions when LAM is effective for a given material. Further, we capture the mechanisms by which LAM fails, providing unprecedented insight into what controls additive manufacturing’s process window, and how to extend it. Using beamlines at both Diamond Light Source and ESRF, new insights are shown into the dynamic evolution of melt features, including track morphology (continuous to balling), pore formation and spatter.

Biography of Professor Peter D. Lee, FIMMM, FICME, CEng, CSci

Peter is Professor of Materials Imaging at The University of Manchester, but is based at the Research Complex at Harwell, where he is Assistant Director for Physical Sciences. His research focusses on the computational simulation and X-ray imaging of materials at a microstructural level. He was one of the pioneers of multi-scale and through process modelling (now termed ICME), working at Alcan on the prediction of defects in light alloy components for companies such as Ford, BMW and Toyota.

Peter is also an avid experimentalist, developing nano-precision rigs that replicate the processing and service performance of materials on synchrotron beamlines, enabling us to see inside materials in 3D as they change in time. His work is revealing how microstructures evolve. His experimental techniques and open-source codes have been exploited internationally by aerospace, automotive, energy and biomedical companies to solve important engineering challenges – from developing additive manufactured human joint replacements to light weight automotive components.

Peter is based at the Research Complex at Harwell, were his group frequently acts as a hub for other academics and industrialists to perform feasibility studies using the large facilities based there, including Diamond Light Source, ISIS Neutron Source, and the Central Laser Facilities.