THE EFFECT OF THERMAL CONDITIONS ON PROCESS DEFECTS IN ELECTRON BEAM DIRECTED ENERGY DEPOSITION

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Date

2023

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University of Texas at Austin

Abstract

Observing process defects at size scales and with sufficient confidence relevant to qualification efforts has not yet been achieved in metal AM, so non-destructive testing (NDT) techniques are used to detect porosity within material deposited. NDT costs can be significant and may not achieve targeted resolution due to geometry and material limitations. In this work, in-process monitoring of Electron Beam Directed Energy Deposition (EB-DED) is enhanced to include three thermal history conditions; inter-pass, melt pool superheat and trailing bead temperatures. Quality scenarios are applied to simulate various process conditions during EB-DED at three different thermal conditions within production relevant use cases and resultant process defects are characterized via high throughput computed tomography. Defects are spatially and temporally registered to process conditions observed during EB-DED and statistically mapped to thermal scenarios. Thermal condition has a strong influence on the quantity of observed process defects, with lower interpass temperature resulting in a larger number of defects.

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