where Hc is the hardening capacity, σUTS is the ultimate strength, and σY is the yield strength. The obtained values of the hardening capacity, Hc of the Mn-modified and base alloys are listed in Table 3. It is seen that the hardening capacity of the Mn-modified
alloy increased from 0.04 to 0.86 due to T6 heat treatment. It is also noticed that the Hc of the Mn-modified alloy was significantly higher than the base alloy in the same state of heat treatment. In general, when a material is strengthened, the YS increases while the hardening capacity increases due to the fact that the capacity of creation and storage of dislocations during plastic deformation increases [42,43]. This was mainly ascribed to the lower YS, higher UTS and ductility of the modified alloy.