The dynamic strain aging behavior of alloy 690 was studied over temperatures ranging from room temperature to 800 °C and strain rates ranging from 10^-5 to 10^-2 s⁻¹. The alloy exhibits a serrated plastic flow behavior due to dynamic strain aging in the temperature range of 200-600 °C. This behavior is characterized by serrations of different types that appear in a sequence F → A/A + B → C + B/C upon the increasing temperature at a constant strain rate or decreasing strain rate at a constant temperature. In some cases, serration type changes during the tensile test at higher strain values. In the dynamic strain aging temperature regime, the alloy exhibits a normal Portevin–Le Chatelier (PLC) behavior at low to intermediate temperatures, which changes to an inverse PLC at higher temperatures when C- type serrations commence. The transition temperature of the normal to the inverse-PLC increases with an increase in the strain rate. The activation energy for the normal-PLC behavior is in the range of 107-120 kJ/mol, while for the inverse PLC behavior, the value is 250 kJ/mol. These activation energy values are attributed to the formation of atmospheres of Cr-C complexes and Cr solutes around dislocations for the two PLC behaviors, respectively. The transition of the normal PLC to the inverse PLC behavior manifests in a change in the fracture mode.