Understanding fatigue crack initiation in Ni superalloys: a study with HR-EBSD, HR-DIC and CP-FEA

  • Date: Nov 17, 2015
  • Time: 01:15 PM - 02:00 PM (Local Time Germany)
  • Speaker: Dr. Ben Britton
  • Imperial College London
  • Location: Max-Planck-Institut für Eisenforschung GmbH
  • Room: Seminar Room 1
  • Host: Prof. Gerhard Dehm
The lifetime of aerospace engineering components is often limited by fatigue. Traditional management strategies presuppose an existing defect length and estimate time to failure through short crack growth and propagation methods, using empirical approaches such as fitting of a Paris’ law. New advances in material processing and production render this argument insufficient to exploit tackle the next generation clean and well-engineered materials, as these growth based empirical studies are too conservative for effective engine management. In this talk, I will outline our recent work focussing on exploiting the next generation of characterisation tools, such as high (angular) resolution electron backscatter diffraction, high (spatial) resolution digital image correlation, combined with geometrically faithful and relatively simple (i.e. limited free parameters) lengthscale based crystal plasticity approaches. These have been brought to bear on a experimental and modelling campaign that focusses on tracking deformation and damage accumulation in single, directionally solidified, polycrystalline and polycrystalline Ni-superalloys with inclusions. In this talk I will outline some highlights from this body work which include: a comparison of ability of HR-DIC and HR-EBSD to recover components of the deformation tensor; understanding accumulated damage and the onset of cracking near non-metallic inclusions; and predicting and understanding accumulated slip in fatigue.
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