Effect of deformation prior to transformation on the mechanical properties of steel 4340

Conclusions

• 1. Reductions up to 75% at 845°C increased the yield strength of quenched steel from 144 to 180 kg/sq.mm without increasing the tensile strength. After tempering at 205°C the change was from 162 to 180 kg/sq.mm. The impact toughness was improved and the embrittlement at 260°C was reduced.

• 2. A reduction by 72% at 540°C raised the tensile strength after quenching, or after quenching + tempering at 220°C, from 193 to 218 kg/sq.mm, and the yield strength from 165 to 197 kg/sq.mm. This was accompanied by a slight decrease of impact toughness. Deformation of elevated temperatures can be utilized in making strip, sheet and wire.