PSI - Issue 54

Magdalena Eškinja et al. / Procedia Structural Integrity 54 (2024) 123–134 M. Eškinja et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 8. Comparison of stress strain curves for HMoS in single and double Q&T condition for the tensile tests conducted in air and under electrochemical charging.

Fig. 9. SEM micrographs for HMoS in a) single Q&T condition and in b) double Q&T condition. Bright inclusions marked in yellow circles are Mo 2 C.

To elucidate the reason behind improved HE resistance, SEM investigation was conducted to examine the changes in the microstructure. From Figure 9 the increased number and more uniform distribution of bright inclusions, which were confirmed by EDX mapping to be Mo 2 C carbides, is clearly visible. As we showed that Mo carbides can act as medium-strong trap, it is most likely that they play major role in improving resistance of double Q&T steel with higher Mo content as well.