OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 27 No. 2 2025 Fig. 7. Median depth of corrosion damage at varying levels of residual strain: hp – results obtained using AXALIT software; hm – results obtained from cross-sectional analysis forming surface at the points of corrosion damage registration is shown in Fig. 6 in the form of blue lines. According to the measurements obtained, the median depth of corrosion damage was determined. A comparison of the results of the median depth measurement from the cross-section micrograph and from the surface photograph in the AXALIT software is shown in Fig. 7. As can be seen from Fig. 7, the results of determining the median depth of corrosion damage using AXALIT software are satisfactory. The obtained dependences of the change in median corrosion damage depth on the residual strain of the material exhibit a similar trend in both cases, indicating a consistency between the results. The results from direct measurement and those obtained using the software differ by a factor of 1.45, as shown in Fig. 8. However, the median corrosion damage depths obtained by the two methods are directly correlated, as evidenced by the linear dependence presented in Fig. 8. The coefficient of determination (R²) for the obtained relationship is 0.91, further indicating a strong agreement between the results. The data observed in Figs. 5, 7, and 8 indicate that during plastic deformation, there is an increase in the penetration depth of corrosion damage into the material. This is because the material fracture process initiates at surface micro-inhomogeneities, which can be considered as dislocations and atoms of chemical elements. Plastic deformation of the material leads to an increase in dislocation density [22, 25-27]. During material deformation, dislocations move due to the slip process. During movement, dislocations collide with grain boundaries, which act as obstacles. Accumulation of dislocations occurs in the grain boundary regions. Plastic deformation leads to the generation of new dislocations and an increase in dislocation collisions. This results in the formation of dislocation clusters that are unable to move through the crystal lattice. Together with impurity atoms diffusing into the grain boundaries, this intensifies the corrosion fracture process. In this case, the grain boundaries are the initiation sites for this process (Fig. 9). Restriction of dislocation movement and formation of a more extensive cluster leads to hardening of the material [20], which affects the grain shape and its average size. The average size is in direct relation to the number of grains in the microstructure, and it affects the extent of grain boundaries. The greater the number of grains, the greater the probability of accumulation of crystal structure defects in these areas and the higher the corrosion susceptibility of the material. However, other parameters of the system under consideration also change during deformation.
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