Experimental Investigation of Principal Residual Stress and Fatigue Performance for Turned Nickel-Based Superalloy Inconel 718.

Yang Hua,Zhanqiang Liu

doi:10.3390/ma11060879

Abstract

Residual stresses of turned Inconel 718 surface along its axial and circumferential directions affect the fatigue performance of machined components. However, it has not been clear that the axial and circumferential directions are the principle residual stress direction. The direction of the maximum principal residual stress is crucial for the machined component service life. The present work aims to focuses on determining the direction and magnitude of principal residual stress and investigating its influence on fatigue performance of turned Inconel 718. The turning experimental results show that the principal residual stress magnitude is much higher than surface residual stress. In addition, both the principal residual stress and surface residual stress increase significantly as the feed rate increases. The fatigue test results show that the direction of the maximum principal residual stress increased by 7.4%, while the fatigue life decreased by 39.4%. The maximum principal residual stress magnitude diminished by 17.9%, whereas the fatigue life increased by 83.6%. The maximum principal residual stress has a preponderant influence on fatigue performance as compared to the surface residual stress. The maximum principal residual stress can be considered as a prime indicator for evaluation of the residual stress influence on fatigue performance of turned Inconel 718.

Highlights

Nickel-based superalloy Inconel 718 (IN718) has excellent mechanical properties and corrosion resistance even at high temperatures [1]
The results showed that both surface residual stresses and the maximum compressive residual stress along axial and circumferential directions were higher when the cutting speeds increased
Through solution heat treatment and aging treatment Inconel 718 was employed as the workpiece material in this paper

Summary

Introduction

Nickel-based superalloy Inconel 718 (IN718) has excellent mechanical properties and corrosion resistance even at high temperatures [1]. It has been extensively used in the aerospace industry for the hot-sections of gas turbine engines such as turbine disks [2,3]. Aero-engine turbine disks work in severe environments with high load, high temperature and high speed. Once the turbine disk has a fatigue fracture failure, the high-energy debris will be generated. These debris are unlikely to be contained by the turbine casting, which can threaten the aircraft safety significantly and may cause catastrophic accident. The turbine disk is classified as one of the fracture-critical parts of gas turbine engines

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