3.3 Results of Charpy Test
The impact toughness of all three states is shown in
Fig. 10. The highest impact toughness is in state B
and the lowest is in state C. Tempering at 280 °C for
3 hours is not appropriate for the material because
impact toughness is reduced. On the other hand,
tempering at 220 °C for 3 hours improves impact
toughness compared to quenched state.