Effect of Hot Rolling on Microstructure and Mechanical Properties of N08120 Ni-Based Superalloy

Abstract:

The microstructure evolution and mechanical properties of the N08120 superalloy rolled at 780 ℃ and deformed through the cumulative reduction of 40%, 60%, and 80% with the single pass reduction of 10% were investigated. The experimental results show that MC and M₂₃C₆ carbides precipitate at grain boundaries and within the grains during deformation. These finely dispersed carbides effectively hinder dislocation motion, thereby enhancing the strength of the material. Dynamic recovery is identified as the predominant softening mechanism during hot rolling, where dislocations progressively reorganize into dislocation cell structures through slip and recombination. Owing to the strong pinning effect of grain boundaries on dislocations and their high interfacial energy, dislocations preferentially accumulate near grain boundaries, inducing localized recrystallization and the formation of fine recrystallized grains. With increasing deformation amount, the alloy texture transitions progressively from Rotated Goss {110}<110> to Rotated Cube {110}<112> and finally to the Copper {112}<111> type. After 40% deformation, work hardening is significant, with the yield strength increasing from 322 MPa to 867 MPa and the microhardness rising from 196 HV_0.5 to 337 HV_0.5. Beyond 40% deformation, both yield strength and microhardness tend to stabilize. This is mainly attributed to the evolution of carbides, dislocation density, substructure, and recrystallization in N08120 superalloy during hot rolling.