Deformation and Microstructure Evolution in Co-Ni-Cr-Mo Superalloy during Hot Working

Deformation and microstructure evolution in Co-33Ni-20Cr-10Mo superalloy during hot deformation are studied by carrying out compression tests between 950 °C and 1200 °C with an increment of 50 °C at strain rates of 0.1, 1, 10, and 30 s⁻¹. The flow curves obtained for the aforementioned strain rates in this temperature range show that this alloy has high work-hardening characteristics; this is due to the strong dislocation-solute interactions associated with dynamic strain aging (DSA). Microstructures deformed at temperatures up to 1050 °C consist of numerous deformation twins and highly dense dislocations, which are attributed to the high activation energy for deformation and the relatively low strain-rate sensitivity m in the temperature range of 950 °C to 1200 °C. Dynamic recrystallization (DRX), which is dependent on the strain rate, occurs at T = 1000 °C, 1050 °C, 1100 °C, 1150 °C, and 1200 °C.