Tempering influence on residual stresses and mechanical properties of AISI 4340 steel

The present work evaluated the tempering temperature influence on microstructure, mechanical properties, and residual stresses of AISI 4340 steel. were measured by X-ray diffraction (XRD) sin2ψ method compared to magnetic Barkhausen noise (MBN). exhibited high tensile values after quenching, but a small relief was observed in treatments at 300 °C 400 °C, which also presented hardness decrease as-quenched condition. XRD MBN analyses indicated that became compressive performed between 500 650 °C. Therefore, combined with appropriate toughness (35 HRC 33 J) obtained from can be used improve properties steel components. Additionally, mathematical model established estimate tempered martensite for different conditions. This showed accuracy (R2 = 0.99) holding time 90 min.