PSI - Issue 68

Bhawesh Chhajed et al. / Procedia Structural Integrity 68 (2025) 708–714 Bhawesh Chhajed et al. / Structural Integrity Procedia 00 (2025) 000–000

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Fig 2 TEM micrographs captured in bright field imaging mode for (a) NSB_250 and (b) NSB_350 specimen

Fig 3 (a) BF image obtained for NSB_250 undeformed specimen (b) corresponding HAADF image; elemental maps obtained using EDS analysis

TEM bright field images for FCGR tested NSB_250 specimen along with corresponding SAED patterns are shown in Figure 4 (a) and (b). Two different regions have been shown in Figure 4 (a) and (d) which represent the microstructural changes observed in the Paris law regime of FCGR tested specimens for NSB_250 condition. Bright field image in Figure 4 (a) suggests heavily deformed ferritic laths. Dense dislocation network is observed at the lath boundaries and across the thickness of laths as well. Dark field image captured corresponding to (110)α spot reveals certain ferritic regions that contain the heavy dislocation network, as shown in Figure 4 (c). Figure 4 (d) represents the bright field image for microtwins generated in RA. Deformation twins can be generated in the RA prior to the martensitic transformation, Jeong et al. (1993). Dark field image in Figure 4 (f) corresponding to the