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The application of geometry corrections for Diffraction Strain Tomography (DST) analysis of a Ni-base superalloy blade

DOI: 10.1017/S0885715613000857 DOI Help

Authors: Nikolaos Baimpas (University of Oxford) , Mengyin Xie (University Of Oxford) , Christina Reinhard (Diamond Light Source) , Alexander Korsunsky (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Powder Diffraction , VOL 28 , PAGES S436 - S447

State: Published (Approved)
Published: September 2013

Abstract: X-ray diffraction is commonly used for non-destructive and precise quantitative determination of internal strain distributions. In recent years tomographic imaging has also been established as a powerful tool for precise non-destructive evaluation of internal structure in materials offering submicron resolution 3D imaging of density distributions. “Diffraction Strain tomography” (DST) concept (Korsunsky, Vorster et al. 2006) has been introduced as a means of tomographic reconstruction of two-dimensional internal strain distributions. The application of this approach during in situ loading has been subsequently demonstrated (Korsunsky et al., 2011). In the present study, similar acquisition strategy was used for diffraction data collection from a Ni-base superalloy turbine blade fabricated by DMLS (Direct Metal Laser Sintering, also sometimes referred to as DLD, Direct Laser Deposition). The experiment was conducted on beamline I12 (JEEP) at Diamond Light Source, UK. Each location within the object was multiply “sampled” (i.e. diffraction patterns were collected containing its contribution) by incident X-ray beams travelling through the sample at different angles. The setup of the beamline also allowed to acquire simultaneously a conventional (absorption tomography) reconstruction of the sample shape. The aim of the experiment was to obtain detailed information about the sample shape, structure, and state. The interpretation of diffraction tomography data requires precise calibration of the sample detector distance at different rotations and positions across the sample, and subsequent application of corrections to remove geometry-induced strain aberrations.

Journal Keywords: Rich Tomography; Synchrontron Monochromatic X-Ray Diffraction; Strain Reconstruction

Subject Areas: Technique Development, Materials

Instruments: I12-JEEP: Joint Engineering, Environmental and Processing