The influence of temperature-strain rate conditions on hot workability and microstructure of powder metallurgy nickel-based superalloy EP741NP

Open School-Conference of NIS Countries Ultrafine Grained and Nanostructured Materials

Ganeev, A.A.^1 ; Valitov, V.A.^1 ; Utyashev, F.Z.^1 ; Imayev, V.M.^1

Institute for Metals Superplasticity Problems, Russian Academy of Sciences, 39 Khalturin st, Ufa

450001, Russia^1

关键词: Compression experiments;    Compression properties;    Fine-grained microstructure;    High angle grain boundaries;    Isothermal compressions;    Nickel- based superalloys;    Recrystallization kinetics;    Uni-axial compression;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/447/1/012062/pdf
DOI  :  10.1088/1757-899X/447/1/012062

来源: IOP

【 摘 要 】

The influence of temperature-strain rate conditions on the compression properties, hot workability and changes in the microstructure after the uniaxial single-step isothermal compression and the three-step isothermal compression with intermediate anneals has been studied for the powder metallurgy (PM) nickel-based superalloy EP741NP. Compression tests were carried out in the temperature range of T = 900-1190 °C to a total strain of e≈1.05. The study of the microstructure was carried out for the cross sections of the deformed samples. The optimal strain temperature in terms of hot workability and recrystallization kinetics was defined as T = 1140-1160 °C, i.e. 4525 °C below the γ′ solvus temperature Ts . Three-step compression experiments with intermediate anneals were performed at the optimal temperature of deformation with a strain rate in the range of = 10-4-10-1 s-1 to obtain improved hot workability and fast recrystallization kinetics. BSE observations and EBSD analysis showed that the three-step uniaxial compression at T = 1140-1160 °C with = 5×10-3 s-1 and intermediate anneals provided reasonable hot workability and the formation of a recrystallized fine-grained microstructure with predominantly high-angle grain boundaries.