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

Zhihao Yao,Jianxin Dong,He Jiang,Jinglin Wang,Biao Zhou,Hongying Wang

doi:10.3390/met10070920

Zhihao Yao, Jianxin Dong + Show 4 more

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https://doi.org/10.3390/met10070920

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Abstract

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.

Highlights

As an advanced wrought nickel-based superalloy strengthened by precipitation of the γ’ phase, HAYNES 282 alloy possesses excellent high temperature strength with good fabricability
The DRX fraction increased with the increase of temperature at any strain rate, and reached complete recrystallization increased with the increase of temperature at any strain rate, and reached complete recrystallization with a DRX fraction over 95% at 1100 ◦ C
The hot deformation behavior, processing map and dislocation evolution of HY282 alloy were investigated in the temperature range of 960–1180 ◦ C and strain rate range of 0.01–10 s−1

Summary

Introduction

As an advanced wrought nickel-based superalloy strengthened by precipitation of the γ’ phase, HAYNES 282 (hereinafter referred to as HY282) alloy possesses excellent high temperature strength with good fabricability. 740H, are widely used in key components of aero engine and gas turbine due to their excellent mechanical properties and high resistance to oxidation/corrosion, while they have fabricability problems [1]. The development of heavy-duty gas turbine, spaceflight and aviation technology has put forward strict requirements on the comprehensive performance of combustor and burning cylinders [2,3]. HY282 alloy was designed in the form of a thin strip to meet the performance. Obtaining uniform fine grains during hot working is one of the ultimate goals to improve the stability and strength of HY282 alloy thin strip.

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