Study on deformation behavior, microstructure evolution and underlying mechanisms of a high N content Ni-Fe-Cr-based alloy

Ni-Fe-Cr-based alloys, due to its excellent strength, oxidation resistance, and corrosion resistance, have gained widespread application in the fields of petrochemical engineering, marine engineering and nuclear power plants. In this paper, isothermal hot compression tests have been carried out to study the hot working characteristics of a high N content Ni-Fe-Cr-based N08120 alloy within the temperature range of 950–1200℃ and strain rates range of 0.01–10 s⁻¹ to a total true strain of 0.9, and an Arrhenius-type constitutive model with strain compensation was established from the stress-strain curves under various conditions. Deformation activation energy map and hot processing map were also constructed, the optimum hot working windows, in which the N08120 alloy exhibited sufficient dynamic recrystallization (DRX), were identified as 1100℃/10 s⁻¹, 1200°C/10 s⁻¹ and 1150–1200℃/0.01 s⁻¹. Detailed microstructural characterizations corresponding to different domains of hot processing map were performed to analyze the deformation mechanisms utilizing electron backscattered diffraction technology (EBSD). The results indicated that the primary hot deformation mechanism of the alloy was discontinuous dynamic recrystallization (DDRX), while under low-temperature conditions (950–1050℃), continuous dynamic recrystallization (CDRX) was more pronounced as an assisted mechanism. This research provides theoretical basis and process guidance for the specific alloy in industrial production.