Characterization of Hot Deformation Behavior and Dislocation Structure Evolution of an Advanced Nickel-Based Superalloy

Abstract

<jats:p>The hot deformation behavior of an advanced nickel-based Haynes282 superalloy was systematically investigated employing isothermal compression tests in the sub-solvus and super-solvus temperature with various strain rates. The influence of deformation temperature and strain rate on the microstructure was studied by transmission electron microscope. The results reveal that the interaction between work hardening and dynamic softening did not reach equilibrium under lower deformation temperature and higher strain rate. The active energy of alloy is around 537.12 kJ/mol and its hot deformation constitutive relationship equation was expressed. According to the processing map and microstructure observations, two unsafe flow instability domains should be avoided. The optimum hot processing condition for homogeneous and fine dynamic recrystallization grains are obtained. TEM micrograph observations indicated that deformation temperature and strain rate affected recrystallization by affecting the evolution of dislocation substructures within the alloy. The nucleation and growth of DRX grains can be promoted by the relatively high deformation temperature and low strain rate. The main mechanism of dynamic recrystallization nucleation preferred to discontinuous dynamic recrystallization and the typical feature of discontinuous dynamic recrystallization showed grain boundary migration nucleation. The findings improve the understanding of hot deformation behavior and dislocation substructures evolution of the superalloy, which benefits the accurate control of microstructures of nickel-based superalloys, and tailors the properties of final components used in the land-based gas turbine.</jats:p>

EBSD Study of Delta-Processed Ni-Based Superalloy

“…In this alloy, the presence of the δ-phase promotes grain refinement during hot working and prevents excessive grain growth during heat treatment operations [3][4][5][6]. Since the development of nickel-based superalloys, several investigations have been conducted to evaluate and optimize their microstructure and performance for different applications [7][8][9][10][11][12][13][14][15]. One of the most common setbacks in the forging industry is obtaining refined microstructures, particularly in areas close to the contact with the dies where the lack of deformation due to friction and high heat transfer conditions avoids any microstructural modification by forging.…”

Investigation on Sub-Solvus Recrystallization Mechanisms in an Advanced γ-γ’ Nickel-Based Superalloy GH4151

“…Generally, it has been widely accepted that discontinuous DRX (DDRX) and continuous DRX (CDRX) are considered as two probably nucleation mechanisms in the DRX process of nickel-based superalloys [ 10 , 11 ]. DDRX involves distinct nucleation and growth stages, which occur in metals with low or medium stacking fault energy [ 12 ].…”