Critical temperature of brittle failure in induction-hardened steel

Conclusions

• 1. For specimens quenched after induction heating we obtained a wider range of optimum tempering temperatures producing maximum impact toughness (180–240°). In this heat treatment the temper brittleness zone is narrowed down.

• 2. The impact toughness of induction-hardened 45KhTR steel at a test temperature of 20° is approximately 20% higher than for steel quenched after heating in a muffle furnace.

• 3. At reduced test temperatures induction heating has considerable advantages, such as the fact that the transition temperature to the brittle state for 45KhT steel is −60°, and −40° for 45KhTR steel; correspondingly, for specimens of both steels quenched after being heated in a muffle furnace the transition point to the brittle state is −20°.