| Abstract | This study investigates the effect of Al on the scratch resistance of two families of Fe-Mn-Al-C steels: Fe-18Mn-xAl-0.7C and Fe-25-Mn-yAl-0.7C, where x = 0, 3, 6, and 9 (wt.%) and y = 0, 3, 6, and 11 (wt.%). The groove morphology was examined using SEM and non-contact profilometry to determine the scratch width for each condition and characterize microstructural changes. Archard’s empirical law was employed to determine the wear coefficient (K) and to compare the present results with those available in the literature for other alloys. The lowest K values were observed for the Fe-Mn-Al-C steels with high Al content, specifically 0.0258 for Fe25Mn11Al and 0.0289 for Fe18Mn9Al. Conversely, higher K values were noted for steels with low Al content, specifically 0.0493 for Fe25Mn0Al and 0.0535 for Fe18Mn3Al. Furthermore, the Fe-Mn-Al-C steels with the lowest Al content (and thus the lowest stacking fault energy) exhibited the highest scratch-hardening despite having the lowest scratch hardness number, specifically Fe18Mn0Al and Fe25Mn0Al steels with values of 0.23 and 0.18, respectively. On the other hand, steels with the highest Al content (and thus high stacking fault energy) displayed the lowest scratch-hardening and the highest scratch hardness number, specifically Fe18Mn9Al and Fe25Mn11Al steels with values of 0.09 and 0.11, respectively. In other words, plastic deformation mechanisms such as TRIP, TWIP, and MBIP in Fe-Mn-Al-C steels play a significant role in scratch resistance up to a critical Al content value; beyond that point, solid solution strengthening becomes the predominant factor. |
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