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Overcoming the drawbacks of plastic strain estimation based on KAM
1Department of Solid Mechanics, KTH Royal Institute of Technology, Teknikringen 8D, Stockholm, SE-100 44, Sweden.
Ultramicroscopy
|September 15, 2017
Summary
This study overcomes limitations in plastic strain estimation using electron backscatter diffraction (EBSD) by refining kernel average misorientation (KAM) calculations. These improvements enhance the reproducibility of plastic strain measurements in materials like Alloy 690.
Area of Science:
- Materials Science
- Metallurgy
- Crystallography
Background:
- Plastic strain estimation is crucial for material performance analysis.
- Electron backscatter diffraction (EBSD) and kernel average misorientation (KAM) are widely used but sensitive to measurement parameters.
- Inconsistencies in KAM-based strain analysis hinder inter-laboratory reproducibility.
Purpose of the Study:
- To address the sensitivities of KAM in plastic strain estimation.
- To develop modified KAM methods for improved reproducibility.
- To validate these modifications against alternative metrics like grain orientation spread (GOS).
Main Methods:
- Refinement of kernel average misorientation (KAM) calculations.
- Comparison of modified KAM with grain orientation spread (GOS) metric.
- Application of both metrics to estimate plastic strain in Alloy 690 heat affected zones.
Main Results:
- The study demonstrates methods to overcome KAM's sensitivity to measurement errors and parameters.
- Modified KAM and GOS metrics yielded consistent plastic strain distribution results.
- Accurate compensation for grain size effects was achieved in the analysis.
Conclusions:
- The proposed modifications enhance the reliability and reproducibility of EBSD-based plastic strain estimation.
- KAM can be reliably used for plastic strain analysis when accounting for its inherent sensitivities.
- This work provides a pathway for more consistent material characterization across different research environments.
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