Abstract
Quantification of residual stress gradients can provide great improvements in understanding the complex interactions between microstructure, mechanical state, mode(s) of failure and structural integrity. Highly focused local probe non-destructive techniques such as X-ray diffraction, electron diffraction or Raman spectroscopy have an established track record in determining spatial variations in the relative changes in residual stress with respect to a reference state for many structural materials. However, the interpretation of these measurements in terms of absolute stress values requires a strain-free sample often difficult to obtain due to the influence of chemistry, microstructure or processing route. With the increasing availability of focused ion beam instruments, a new approach has been developed which is known as the micro-scale ring-core focused ion beam-digital image correlation technique. This technique is becoming the principal tool for quantifying absolute in-plane residual stresses. It can be applied to a broad range of materials: crystalline and amorphous metallic alloys and ceramics, polymers, composites and biomaterials. The precise nano-scale positioning and well-defined gauge volume of this experimental technique make it eminently suitable for spatially resolved analysis, that is, residual stress profiling and mapping. Following a summary of micro-stress evaluation approaches, we focus our attention on focused ion beam-digital image correlation methods and assess the application of micro-scale ring-core methods for spatially resolved residual stress profiling. The sequential ring-core milling focused ion beam-digital image correlation method allows micro- to macro-scale mapping at the step of 10-1000 μm, while the parallel focused ion beam-digital image correlation approach exploits simultaneous milling operation to quantify stress profiles at the micron scale (1-10 μm). Cross-validation against X-ray diffraction results confirms that these approaches represent accurate, reliable and effective residual stress mapping methods.
Original language | English |
---|---|
Pages (from-to) | 426-444 |
Number of pages | 19 |
Journal | Journal of Strain Analysis for Engineering Design |
Volume | 50 |
Issue number | 7 |
Early online date | 4 Aug 2015 |
DOIs | |
Publication status | Published - 1 Oct 2015 |
Keywords
- digital image correlation
- focused ion beam
- micro-scale
- Residual stress
- ring-core
- X-ray diffraction
ASJC Scopus subject areas
- Modelling and Simulation
- Mechanics of Materials
- Mechanical Engineering
- Applied Mathematics