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Residual stress analysis in thermally sprayed layer composites, using the hole milling and drilling method

  • R. Gadow
  • M. J. Riegert-Escribano
  • M. Buchmann
Reviewed Papers

Abstract

Residual stresses are related to the thermophysical properties of substrate and coating materials and occur after the coated component has undergone thermal spraying and machining processes. All residual stresses in layer composites result from different individual stress mechanisms occurring during the manufacturing process, mainly based on heat and mass transfer during the coating deposition. Using the hole-milling-and-drilling method, residual stress fields can be measured in a quasi-nondestructive way over the drilling depth with appropriate resolution. In several drilling and milling operations, a cylindrically shaped hole is brought step by step into the component surface. The residual stresses are locally relieved due to material removal, deform the surface around the drilled microhole, and are measured by high-resolution measurement tools (e.g., strain gages (DMS)), for every drilling step in the form of relaxed surface strains. Using calibration curves and material data (E, μ), the measured surface strains are converted into nominal strains at the bottom of the drilled hole for every drilling step. Out of the differentiated strains, in-plane stress fields can be incrementally determined by Hooke’s law. This study describes residual stress measurement features, the finite-element method (FEM) calculation, and the idealization of calibration curves, as well as the results of exemplary stress measurements.

Keywords

calibration curves hole-drilling method layer composites residual stresses thermal spraying 

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Copyright information

© ASM International 2005

Authors and Affiliations

  • R. Gadow
    • 1
  • M. J. Riegert-Escribano
    • 1
  • M. Buchmann
    • 2
  1. 1.Institute for Manufacturing Technologies of Ceramic Components and CompositesIMTCCC, University of StuttgartStuttgartGermany
  2. 2.Federal-Mogul Friedberg GmbHFriedbergGermany

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