Steels are engineered with different microstructures for different applications. Austenite, ferrite, martensite and bainite are common phases in different steel alloys and the relative proportions of these different phases impact how the steel will behave in different regimes. For example, the amount of martensite will influence both strength and toughness. As a result, being able to measure the relative presence of these phases is important.
Electron back-scattering diffraction (EBSD) can readily separate austenite and ferrite due to a significant crystallographic difference between these two phases. In contrast, distinguishing martensite, bainite and ferrite is a challenge as the crystal structure of these three phases is essentially the same. All three have a body centred cubic (BCC) structure, with martensite and bainite being only slightly distorted from the ferrite BCC structure. This difference in crystal structure has presented challenges to researchers for many years.
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