PSI - Issue 75

Jérémie BOUQUEREL et al. / Procedia Structural Integrity 75 (2025) 442–449 Jérémie BOUQUEREL/ Structural Integrity Procedia (2025)

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Figure 3: Coupled FSD micrographs and IQ-LSM maps for both HDEN1 (a,c) and HDEU1 (b,d) valves (step size = 50 nm)

Figure 4: IPF (/ valve axis) and KAM maps for both HDEN1 (a,c) and HDEU1 (b,d) valves (step size = 50 nm)

At this scale of observation, no other characteristic features of other dislocation structuring, linked to fatigue damage, have been pointed out. These observations are in agreement with the hardness measurements performed on both valves at the macroscopic level. Indeed, the presence of less misorientation attest of lower tension and dislocations within the matrix. Together with the grain size growth, the resulting mechanical properties deterioration (i.e., observed softening) is evident. Moreover, the tensile strength and yield stress decreases would result in decreased