Datasets acquired with correlative microscopy method for delineation of prior austenite grain boundaries and characterization of prior austenite grain size in a low-alloy high-performance steel

Abstract

Prior studies on martensitic steel microstructures have either delineated the prior austenite grain boundaries via chemical etching or reconstructed the prior austenite grains from crystallographic orientations measured with electron backscattered diffraction (EBSD). To appropriately validate the reconstruction algorithms, the EBSD data need to be collected on martensitic microstructures, where the prior austenite grain boundaries are delineated with techniques such as chemical etching that can serve as ground truth for comparison with the reconstructed prior austenite grains. In this article, the method of correlative microscopy is employed to collect scanning electron microscope (SEM) image and automated EBSD scan data from the same region of an appropriately etched steel specimen. The SEM images and automated EBSD scan data are presented for five different fields of view in the specimen. These datasets are analyzed and discussed in the accompanying article titled “Correlative microscopy for quantification of prior austenite grain size in AF9628 steel” [1].

Probabilistic Reconstruction of Austenite Microstructure from Electron Backscatter Diffraction Observations of Martensite

“…Additionally, all recorded grain sizes are measured in accordance with ASTM E2627-23 (ASTM E2627-23, 2013), combining parent and twins into a single entity and eliminating all grains residing on the boundary of the EBSD map for direct comparison with grain size measurements following ASTM E112 (ASTM E112-13, 2013). Additionally, as validation of the reconstruction code, the algorithms are compared with an SEM micrograph of the same sample analyzed by Sinha et al (2017, 2019 a , 2019 b ), in which the surface has been prepared with an etchant that preferentially attacks the PAGBs.…”

“…For the purposes of comparing the algorithms described above, an EBSD scan and secondary electron imaging of a prior austenite etched surface were performed on the same area of a specimen of AF9628 steel. Further details on the alloy composition and heat treatment, etchant composition, sample preparation, and imaging can be found in references (Sinha et al, 2017, 2019 a , 2019 b ). Inverse pole figure maps for the martensitic microstructure as well as the SEM images highlighting the PAG structure are shown in Figures 2a and 2b.…”

“…The etching procedure that produces the clearly identifiable prior austenite boundaries in Figure 2b was developed specifically for this steel composition (Sinha et al, 2017). EBSD and secondary electron imaging were been performed on the same areas of these specimens for the purposes of correlative microscopy (Sinha et al, 2019 a , 2019 b ), and these datasets are useful for validation of the austenite reconstruction algorithms. To the authors’ knowledge, the present work constitutes the first automated austenite reconstruction for which direct comparison to conventionally etched experimental results has been made.…”

“…When applying the ASTM E112-13 measurement standard, five separate field of views were observed for the AF9628 sample and reconstructions were performed using an SEM-based etching method (Sinha et al, 2017, 2019 a , 2019 b ) and the mixed-space reconstruction technique. Both mean lineal intercept line lengths and ASTM grain size numbers were recorded, with the results showing a strong correlation to each other.…”