EFFECT OF TEMPERING ON THE TOUGHNESS OF A CR-MO BAINITIC STEEL

The effect of tempering on impact and fracture toughness properties of a Cr-Mo bainitic steel was studied in the quenched and stress relieve d (Q & SR) condition. The lowest tempering parameter used resulted in considerable improvement in impact properties. Further tempering incre ased the upper shelf energy, had a minor effect on the transition temp erature, and increased both the initiation fracture toughness (J(IC)) and the tearing modulus (T). However, the effect on J(IC) and T was mu ch greater than the effect on the impact upper shelf energy. The resul ts were discussed in light of the changes in microstructure and flow p roperties due to tempering.