Non-dimensional process maps for normalized dilution limits in laser direct metal deposition

Chaitanya Vundru, Ramesh Singh, Wenyi Yan, Shyamprasad Karagadde

Research output: Chapter in Book/Report/Conference proceedingConference PaperOther

2 Citations (Scopus)

Abstract

The quality and integrity of laser direct metal deposition (DMD) processes primarily depend on the substrate dilution and the nature of residual stresses in the deposited layer. An adequate amount of melting of the substrate is required to ensure the formation of sound metallurgical bond between the deposited layer and substrate. Insufficient melting and excessive dilution may lead to adverse effects. Furthermore, the dilution also controls the location of the melt front in substrate where maximum tensile residual stresses occur. The presence of tensile residual stresses in the deposited layer may be detrimental to service life, especially, for components repaired using DMD. These challenges can be overcome by predicting and controlling the dilution and the nature of residual stress as a function of process parameters. To model the direct metal deposition process, a 3D coupled metallo-thermomechanical finite element model is employed to predict the temperature and the residual stress due to thermomechanical interactions and metallurgical transformations and the substrate dilution. Non-dimensional process parameters affecting the dilution in laser DMD have been identified using Buckingham-π theorem. The metallo-thermomechanical model is used to develop empirical relationships via regression to correlate the dimensionless process parameters with the dilution. These correlations are employed in developing the isopleths in the form of process maps, which could predict regions of inadequate fusion and excessive dilution (unduly large substrate melting). It may be noted that the limiting value of dilution corresponds to the condition where the entire deposited layer (cladding) is under compressive residual stresses. Any dilution higher than this will result in excess substrate melting which is undesirable. The limiting values of normalized dilution are estimated to be 1 and ∼1.3 corresponding to complete deposit-substrate fusion and presence of entirely compressive residual stress in deposition, respectively. These process maps are designed to provide a theoretical framework for understanding the influence of process parameters and provide informed decisions on the selection of appropriate process parameters for ensuring the quality and integrity of the deposition.

Original languageEnglish
Title of host publication47th SME North American Manufacturing Research Conference
PublisherElsevier
Pages712-721
Number of pages10
DOIs
Publication statusPublished - 2019
EventSME North American Manufacturing Research Conference 2019 - Erie, United States of America
Duration: 10 Jun 201914 Jun 2019
Conference number: 47th

Publication series

NameProcedia Manufacturing
PublisherElsevier
Volume34
ISSN (Print)2351-9789

Conference

ConferenceSME North American Manufacturing Research Conference 2019
Abbreviated titleNAMRC 2019
CountryUnited States of America
CityErie
Period10/06/1914/06/19

Keywords

  • Dilution
  • Laser cladding
  • Metallo-thermomechanical finite element model
  • Non-dimensional parameters
  • Process maps
  • Residual stress

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