Abstract

The formation and evolution of shear bands in Inconel 718 nickel-base superalloy under plane strain compression was investigated in the present work. It is found that the propagation of shear bands under plane strain compression is more intense in comparison with conventional uniaxial compression. The morphology of shear bands was identified to generally fall into two categories: in “S” shape at severe conditions (low temperatures and high strain rates) and “X” shape at mild conditions (high temperatures and low strain rates). However, uniform deformation at the mesoscale without shear bands was also obtained by compressing at 1050 °C/0.001 s−1. By using the finite element method (FEM), the formation mechanism of the shear bands in the present study was explored for the special deformation mode of plane strain compression. Furthermore, the effect of processing parameters, i.e., strain rate and temperature, on the morphology and evolution of shear bands was discussed following a phenomenological approach. The plane strain compression attempt in the present work yields important information for processing parameters optimization and failure prediction under plane strain loading conditions of the Inconel 718 superalloy.

Highlights

  • The precipitation-hardened Inconel 718 nickel-base superalloy has been widely used in the manufacturing of critical components in aircraft engines and land-based gas turbines, primarily due to the excellent mechanical properties at high temperatures as well as the extraordinary corrosion-oxidation resistance [1,2]

  • Recent studies show that the flow softening behavior is closely related to various special microstructure characteristics such as shear bands, the precipitation of second phase and strain localization [4,5,6], except for the well-known dynamic recrystallization (DRX) [7] and dynamic recovery (DRV) [8], wherein the propagation of shear band characterized by narrow bands is usually found during the high strain rate inelastic deformation process due to the intense shear straining

  • A study of the formation and evolution of shear bands in nickel-base Inconel 718 superalloy was performed by means of plane strain compression and finite element method (FEM) simulation in the present work

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Summary

Introduction

The precipitation-hardened Inconel 718 nickel-base superalloy has been widely used in the manufacturing of critical components in aircraft engines and land-based gas turbines, primarily due to the excellent mechanical properties at high temperatures as well as the extraordinary corrosion-oxidation resistance [1,2]. The hot-working approach at high temperature usually results in complex localized deformation. In this case, the alloys will experience a softening process and the applied forming force is sensitive to processing parameters such as temperature and strain rate [3]. Recent studies show that the flow softening behavior is closely related to various special microstructure characteristics such as shear bands, the precipitation of second phase and strain localization [4,5,6], except for the well-known dynamic recrystallization (DRX) [7] and dynamic recovery (DRV) [8], wherein the propagation of shear band characterized by narrow bands is usually found during the high strain rate inelastic deformation process due to the intense shear straining. The present work for Inconel superalloy yields superalloy yields important information for the optimizing of processing parameters and failure important the optimizing predictioninformation under planefor strain conditions.of processing parameters and failure prediction under plane strain conditions

Experimental Procedures
Figure
As in Figure
Characterization of Shear Bands
Etched microstructures of Inconel
Initiation of Shear Bands
Theaof distribution damage factorof in 718
The distribution of of thethe effective inInconel
Evolution of Shear Bands
Effective strain‐rate distribution of Inconel
Conclusions
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