Melt pool morphology in directed energy deposition additive manufacturing process

Abstract

Directed Energy Deposition Additive Manufacturing (DED-AM) is one of the principal AM techniques being explored for both the repair of high value components in the aerospace industry as well as freeform fabrication of large metallic components. However, the lack of fundamental understanding of the underlying process-structure-property relationships hinders the utilisation of DED-AM for the production or repair of safety-critical components. This study uses in situ and operando synchrotron X-ray imaging to provide an improved fundamental understanding of laser-matter interactions and their influence on the melt pool geometry. Coupled with process modelling, these unique observations illustrate how process parameters can influence the DED-AM melt pool geometry. The calibrated simulation can be used for guidance in an industrial additive manufacturing process for microstructure and quality control.

Enhanced osseointegration through direct energy deposition porous coating for cementless orthopedic implant fixation

“…Throughout the DED coating process, a high-power laser beam generates a melt pool across the surface of the base metal, and Ti metallic powder is partially melted and fused with a CoCr substrate 28 , 29 . During this process, due to the fast heating/cooling and the steep temperature gradients at the melt pool area, (1) intermetallic CoCr-Ti compounds can be formed, and (2) residual stress can be accumulated at the CoCr-Ti interface 30 – 34 . Since the intermetallic compounds are inherently brittle, these intermetallic compounds can reduce fatigue life 28 , 35 .…”

A review on additive manufacturing for aerospace application

“…Directed Energy Deposition (DED) method is used for both the repair of high-value components in the aerospace industry as well as freeform fabrication of large metallic components [49]. Direct energy deposition using lasers as the source is the best process to repair aerospace components.…”

Synchrotron imaging derived relationship between process parameters and build quality for directed energy deposition additively manufactured IN718

“…After stabilisation, each variable is normalised by the standard deviation of the transformed repeatability noise distribution 2 . In this domain, each variable has the property of being in units of standard deviations of noise.…”

“…In 2019, Chen et al [1] implemented the world's first L-DED process replicator on the Diamond Light Source, UK, and reported first-hand information including the melt pool behavior, defect formation, and micro-structural revolution of the process. In-situ and operando fast acquisition Synchrotron X-ray imaging, as a promising approach, has been applied to LAM, assisting the interpretation of the processes [2][3][4] with a series of previously unseen phenomena have been revealed in both real and reciprocal space. Chen et al [5] used X-ray radiography to visualise how keyhole formation connects to porosity during laser powder bed fusion (L-PBF).…”