Evaluation of Electrospark Deposition

Authors
  1. MacKnight, E.B.
  2. Hyatt, C.V.
Corporate Authors
Defence R&D Canada - Atlantic, Dartmouth NS (CAN)
Abstract
This report examines the suitability of electrospark deposition for use in the repair and reclamation of Naval components. Materials considered during this evaluation included Ni- Cr-Mo, Ta, Co-Cr-W, and Cu-Be electrodes applied to mild steel, as well as Ni-Cr-Mo and WC-Co applied to 304 stainless steel and CSA grade 4021 350WT steel. Inconel, Monel, and nickel-aluminum-bronze were applied to 350WT as well as to base material of matching composition. The deposit thickness ranged from 5µm to 5mm. The heat affected zone (HAZ) ranged from 5µm to 10µm, determined by SEM and microhardness analysis. As in previous work, cracking occurred in some deposits particularly in the WC-Co coating, but not in the Cu-Be coating. Cracks were not found to occur when the electrode and the substrate were of the same material, for the cases examined in this work. Pre-heating prevented cracks in the Ni-Cr-Mo coating. Bend tests showed that the coatings were more brittle than mild steel substrates, and no spalling was found to occur. The porosity of the coating was found to increase with increasing thickness and with increased electrode diameter. Metallography, SEM, and mechanical testing showed the deposits were metallurgically bonded, as expected for a weld deposit. Examination of the electrodes found that they were simple and straightforward to produce. This was confirmed by manufacturing them in-house using electrostatic discharge machining (EDM) and turning methods.

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Keywords
Arc Spark Deposition;Surface treatment;Surface hardening;Repair and reclamation;Metallography
Report Number
DRDC-ATLANTIC-TM-2001-137;DREA-TM-2001-137 — Technical Memorandum
Date of publication
01 Aug 2001
Number of Pages
60
DSTKIM No
CA032775
CANDIS No
531992
Format(s):
Electronic Document(PDF)

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