PSI - Issue 54

Liese Vandewalle et al. / Procedia Structural Integrity 54 (2024) 180–187 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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The material austenitized at 950°C consisted of mainly ferritic grains with some bainitic regions. Again, significant secondary hardening was observed, indicating the precipitation of vanadium carbides upon tempering. On the SEM images, shown in Figure 2b, very small white particles could be observed inside the ferritic grains. However, no vanadium enrichment could be observed by EDX. TEM investigation on the other hand, could clearly visualize the presence of vanadium carbides, as can be seen in Figure 3b. These carbides might be identified as the larger undissolved carbides while the precipitated carbides were again too small for observation but were present indeed, since hardness again increased upon tempering as shown in Figure 4. This is in strong contrast with the Fe C-Ti alloys which showed clear presence of large undissolved carbides in the SEM images. a) b)

Figure 3: TEM images and corresponding EDX data from the Fe-C-V alloys austenitized at (a) 1250°C and (b) 950°C

Figure 4: Hardness values of the Fe-C-V alloys austenitized at 950°C and 1250°C in both the AsQ and the Q&T condition.