3.2. Mechanical properties
The mechanical properties of the steel samples at different
tempering conditions are evaluated and the representative engineering
stress–strain curves and true stress–strain curves are
depicted in Fig. 4. It can be seen that the strength and hardness
values are similar at all the tempered conditions, Fig. 5(a).
A marginal increase in strength and hardness is observed with
increasing the tempering time. However, there is a gradual
decrease in ductility measured in terms of percentage elongation
with increase in tempering time, Fig. 5(b). There is a significant
effect of tempering time on the Charpy impact values of the