Tailoring the crystallographic texture of pure copper through control of the scanning strategy in Electron Powder Bed Fusion

Abstract

There has been increasing interest over the past few years to evaluate how additive manufacturing can be used to tailor the microstructure of metallic materials. The objective of this work is to demonstrate through a few illustrative examples the possibility to tailor the crystallographic texture of pure copper processed by Electron Powder Bed Fusion (PBF-EB) by manipulating the molten pool morphology via the scanning strategy. We illustrate schematically how changes in molten pool geometry via modifications of the scanning strategies can affect texture development. Different processing conditions are selected to produce dense samples by PBF-EB while altering the crystallographic texture. The samples produced are examined by optical microscopy and Electron Back-Scattered Diffraction (EBSD) to characterize the molten pool geometry and the inherited microstructure to experimentally validate the pragmatic approach suggested in this work. Manipulations of the scanning strategies are shown to be efficient to produce a strong Cube texture or Goss texture or alternatively, a mixture between the two. A Cube texture is generated by promoting the formation of a melt pool with a flat geometry (its width being much larger than its depth). A Goss texture results from melt pools having a more hemispherical geometry with a large overlap between adjacent tracks. Adjusting the hatch spacing is a good way to achieve a mixture between columnar grains having a Cube texture and others exhibiting a Goss one. The results of this work could be considered as a guideline to tailor the microstructure of other cubic materials processed by PBF-EB.