Oral Presentation 26th ACMM “2020 Visions in Microscopy”

Influence of scan strategy on the microstructural evolution of electron beam additively manufactured Inconel-738 – a complementary APT and EBSD study (#93)

Bryan Lim 1 2 , Hansheng Chen 1 2 , Andrew Breen 1 2 , Nima Haghdadi 3 , Xiaozhou Liao 1 , Sophie Primig 3 , Sudarsanam Suresh Babu 4 5 , Simon P Ringer 1 2
  1. School of Aerospace, Mechanical & Mechatronic Engineering, The University of Sydney, Sydney, NSW, Australia
  2. Australian Centre for Microscopy & Microanalysis, The University of Sydney, Sydney, NSW, Australia
  3. School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW, Australia
  4. Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville, TN, USA
  5. Manufacturing Demonstration Facility, Oak Ridge National Lab, Knoxville, TN, USA

Additive manufacturing (AM) has long since evolved from its initial mode of use in rapid prototyping to com­mercial manufacturing. AM Ni-based superalloys have found use in the design of critical components in the aerospace industry due to its ability to retain its mechanical properties at elevated temperatures near its melting temperature[1]. Furthermore, with advances in electron beam melting (EBM) powder-based AM, previously ‘hard to weld’ high strength superalloys with high Al and Ti contents have been produced with no or minimal crack propagation[2]. However, the thermodynamic phenomena in metal AM have been confirmed to be significantly different to steady-state conditions assumed in traditional processes[3].

Here we investigate the microstructural changes of AM ‘hard to weld’ Ni-based superalloy Inconel-738, across different scan strategies and build locations to rationalise the effects of new liquid/solid (l/s) and solid/solid (s/s) interface instabilities that arise with AM. The data is also used to help understand how thermal gradients influence the final microstructure and ultimately the integrity of mechanical properties in the resulting builds. Electron back-scattered diffraction (EBSD) is used to observe microstructure and texture evolution. This is coupled with complementary atom probe tomography (APT) for atomic scale chemical information at interfaces.

  1. [1] Kumar, L.J. et al., Current Trends of Additive Manufacturing in the Aerospace Industry. In: Wimpenny D. et al. “Advances in 3D Printing & Additive Manufacturing Technologies” (2017). Springer, Singapore, p. 39.
  2. [2] Chauvet, E. et al., Acta Materialia 142 (2018), p. 82.
  3. [3] Sames, W. J. et al., International Materials Reviews 61 (2016), p. 315.