Anlysis of Seeded Defects in Laser Additive Manufactured 300 M Steel

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Authors
  1. Farrell, S.P.
  2. Deering, J.
Corporate Authors
Defence Research and Development Canada, Atlantic Research Centre, Halifax NS (CAN);DALHOUSIE UNIV, HALIFAX NS (CAN) DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
Abstract
This research activity was initiated to better assess the capacity for traditional nondestructive testing (NDT) approaches to ascertain the defects inherent to materials fabricated through a directed energy laser additive manufacturing (LAM) process. A methodology was developed to intentionally seed defects in 300M steel specimens through intermittent modification of fabrication parameters. Several 300M steel specimens were fabricated and the concentration of defects or bulk density was characterized using optical microscopy and variations of the Archimedes' principle. Specimens were then evaluated using NDT (radiographic testing, ultrasonic testing). Results show that by using n-hexane as the displacement liquid, the Archimedes' principle was found to have repeatability in density values of 0.1 + 0.1 %. The results reveal the unqiue defects produced through the LAM process and the limitations for conventional NDT techniques to adequately detect defects in LAM materials. Ultrasonic testing was found to be a promising tool for assessing the LAM defect distribution. Future work will focus on LAM alloys with higher densities and relate microstructure and defects to overall material performance.
Keywords
additive manufacturing;directed energy;selective laser melting;Archimedes' principle;density;defects;porosity;ultrasonic;spectroscopy;radiographic testing
Report Number
DRDC-RDDC-2018-P104 — External Literature (P)
Date of publication
01 Jul 2018
Number of Pages
16
Reprinted from
Journal of Materials Performance and Characterization Volume 7, No. 1 Pages 300 315 doi:10.1520/MPC20170162 April 2018
DSTKIM No
CA046902
CANDIS No
807320
Format(s):
Electronic Document(PDF)

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