PSI - Issue 42

Rui F. Fernandes et al. / Procedia Structural Integrity 42 (2022) 1054–1060 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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3. Results and discussion Figure 2 displays the average hardness values for the three series, and they were calculated based on measurement of ten different aleatory points. It is possible to note that the AB specimen has higher hardness, with an average value of 165 HV. In another hand, the heat treatments are responsible for a decrease in the hardness values of HIP and 250ºC specimens, that have an average value of 116 HV and 114 HV, respectively. The hardness reduction identified in the heat-treated samples was about 30% when compared with the AB specimen.

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Fig. 2. Hardness values for AB, HIP and 250ºC specimens.

In Figure 3 it is presented a comparison between the effect in the FCG behavior of the different heat treatments and the As-built state for R=0.05. It is possible to understand that the differences in the hardness of the material have led to different FCG rates. Looking into detail, the higher values of hardness correspond to the higher values of FCG rate of the AB specimen. In the other hand, the similar values of hardness between HIP and 250ºC lead to similar values of FCG rate between each one, showing high fatigue resistance.