Orientation Dependence of High Cycle Fatigue Behavior of a &lt;111&gt; Oriented Single-Crystal Nickel-Based Superalloy

Bin Hu,Shusuo Li,Yanling Pei,Shengkai Gong

doi:10.3390/met11081248

Abstract

High cycle fatigue failure has been recognized as one of the major forms of failure of aero-engine blades. This paper presents the high cycle fatigue testing of a Ni-based superalloy near <111> orientation at 800 °C. The fracture morphology and dislocation configuration were analyzed in detail by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to indicate the influence of orientation deviation degree on the high cycle fatigue properties. The results show that the orientation deviation significantly affects the initiation of the slip systems, which is closely related to fatigue performance. The best fatigue life appears on the precise <111> orientation, and the deformation behavior is controlled by multiple sets of equivalent <110> {111} slip systems. With the increase in orientation deviation, the fatigue properties of the alloy degenerate significantly. On the boundary of <111>-<001>, two groups of <110> {111} slip systems with the maximum Schmid shear stress dominate the deformation behavior. On the other hand, on the <111>-<011> boundary, the formation of stacking faults and rapid cutting of γ’ precipitates results in a negative effect on the fatigue life.

Highlights

Nickel-based single-crystal superalloys have been widely used as components in the hot end of advanced aircraft engines and gas turbines due to their excellent hightemperature strength, oxidation resistance and creep properties [1,2]
The master alloy is prepared by vacuum induction melting, and the single-crystal (SX) rods with different deviations from [111] were prepared by highrate solidification (HRS) directional solidification with the seed crystal method
The initiation and propagation of fatigue cracks are the of periodic slip ofslip the slip system, that is, cyclic plastic caused bycaused dislocation result of periodic of the slip system, that is, cyclicdeformation plastic deformation by movement.movement

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Nickel-based single-crystal superalloys have been widely used as components in the hot end of advanced aircraft engines and gas turbines due to their excellent hightemperature strength, oxidation resistance and creep properties [1,2]. In the actual service process, turbine blades are often subjected to fatigue damage with cyclic loading, except for creep damage caused by constant centrifugal stress. Among the many factors that cause engine failure, high cycle fatigue (HCF) has proven to be the most common reason [3]

Methods

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Discussion

Conclusion