Investigation of flow behavior and microstructure modification of ATI425 alloy with initial martensite microstructure in α/β phase and β single phase

Hot deformation behavior and microstructure evaluation of ATI425 alloy with initial martensite microstructure in single-phase and two-phase region in the temperature range of 700-1100˚C and strain rate of 0.001-1s-1 were investigated. The flow curves of the alloy in the α/β region and β-single phase showed that the flow softening of the alloy is the result of spheridization of alpha plates and dynamic recovery and dynamic recrystallization in the α/β phase and β single phase, respectively. In the α/β phase region at low temperatures and low strain rates, the splitting of the alpha plates and the penetration phenomenon are the main causes of alpha plate sphericity and the structure modification mechanism. Kinetic analysis of the alloy was calculated after removing the effect of adiabatic heat and friction. The activation energies for the ATI425 alloy were calculated to be 403.226 kj/mol and 201.038 kj/mol in the α/β and β regions, respectively. The linear relationship between the Zener-Holman parameter and the stress indicates that the flow stress follows the predicted trend of the equation. The process map extracted at 0.5 strain showed that the three zones, instability, safe zone and peak zone with power dissipation efficiency 0 -0.30%, 30-40% and above 40%.