Influence of Surface Anomalies Following Hole Making Operations on the Fatigue Performance for a Nickel-Based Superalloy

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
C. Herbert ◽  
D. A. Axinte ◽  
M. Hardy ◽  
P. Withers
Keyword(s):  
Free Surface ◽  
Fatigue Life ◽  
Surface Integrity ◽  
Low Cycle Fatigue ◽  
White Layer ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Nickel Based Superalloy ◽  
Aero Engine ◽  
Hole Making

Aero-engine manufacturers are continuously striving to improve component performance and reliability while seeking to increase the efficiency of manufacturing to reduce costs. Efficiency gains by using higher rates of material removal, however, can be counter-productive if they give rise to surface anomalies that distort the material microstructure and reduce the resistance of the material to fatigue crack nucleation. This paper investigates the effect of hole making processes and parameters on surface integrity and the initiation of cracks from low-cycle fatigue (LCF). It reports the dependence of elevated temperature (600 °C) low-cycle fatigue performance of nickel alloy RR1000 from surfaces produced from hole making and subsequent surface conditioning. As-machined surfaces include a reference “damage-free” surface, and two distorted microstructures: (i) a white layer, produced to a depth of 5 and 10 μm and (ii) a distorted gamma prime (γ') structure, produced to a depth of 10 and 15 μm. The effect of shot peening damage-free and 10 μm deep white layer surfaces was also evaluated. It was found that the presence of white layer significantly reduced fatigue performance compared with that shown by the damage-free surface, regardless of whether the white layer was subsequently shot peened or not. In contrast, surfaces showing distorted γ' structures produced much less debit in fatigue life and only from a depth of 15 μm. These results have been rationalized from an examination of fracture surfaces and from measurement of residual stresses before and after fatigue testing. This research is of particular importance as it is among the few reports that quantify the effect of different levels of work piece surface integrity on the fatigue life of a nickel-based superalloy that has been developed for critical rotating components in aero-engine applications.

The Role of Surface Topography on Fatigue Behaviour of Nickel Based Superalloys

2014 ◽  
Vol 891-892 ◽  
pp. 48-53 ◽  
Author(s):  
Dennise Tanoko Ardi ◽  
Yue Gang Li ◽  
Kelvin Hau Kong Chan ◽  
Liam Blunt ◽  
M.R. Bache
Keyword(s):  
Fatigue Life ◽  
Surface Topography ◽  
Low Cycle Fatigue ◽  
Three Dimensional ◽  
Fatigue Behaviour ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Nickel Based Superalloy ◽  
Topographic Parameters

Advanced areal (three-dimensional) characterisation of surface topography was applied to laboratory scale fatigue test specimens manufactured from the nickel based superalloy Alloy720Li. Finishing was deliberately manipulated to offer four distinct grades of topography. Subsequent low cycle fatigue performance was then correlated to a range of parameters selected to represent the surface topography. The aim of the ongoing study is to predict fatigue performance and aid to establish correlations between topographic parameters and fatigue life.

Low-Cycle Fatigue Performance of Buckling Restrained Braces and Assessment of Cumulative Damage under Severe Earthquakes

2018 ◽  
Vol 763 ◽  
pp. 867-874
Author(s):  
Yu Shu Liu ◽  
Ke Peng Chen ◽  
Guo Qiang Li ◽  
Fei Fei Sun
Keyword(s):  
Fatigue Life ◽  
Energy Dissipation ◽  
Structural Reliability ◽  
Low Cycle Fatigue ◽  
Engineering Application ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Variable Amplitude ◽  
Buckling Restrained Braces ◽  
Energy Dissipation Devices

Buckling Restrained Braces (BRBs) are effective energy dissipation devices. The key advantages of BRB are its comparable tensile and compressive behavior and stable energy dissipation capacity. In this paper, low-cycle fatigue performance of domestic BRBs is obtained based on collected experimental data under constant and variable amplitude loadings. The results show that the relationship between fatigue life and strain amplitude satisfies the Mason-Coffin equation. By adopting theory of structural reliability, this paper presents several allowable fatigue life curves with different confidential levels. Besides, Palmgren-Miner method was used for calculating BRB cumulative damages. An allowable damage factor with 95% confidential level is put forward for assessing damage under variable amplitude fatigue. In addition, this paper presents an empirical criterion with rain flow algorithm, which may be used to predict the fracture of BRBs under severe earthquakes and provide theory and method for their engineering application. Finally, the conclusions of the paper were vilified through precise yet conservative prediction of the fatigue failure of BRB.

scholarly journals Research on the Fatigue Performance of TC6 Compressor Blade under the CCF Effect

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Zhang Yakui ◽  
Guo Shuxiang
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Compressor Blade ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Test Rig ◽  
Source Characteristics ◽  
Fracture Appearance ◽  
Fatigue Life Reduction

This paper studied the influence of high and low combined fatigue (CCF) on compressor blade fatigue performance. We investigated the coupling between low cycle fatigue (LCF) loading from centrifugal force with high cycle fatigue (HCF) loading from vibration and determined the blade disc vibration frequency using static analysis at maximum rotational speed. We designed and constructed a combined fatigue test rig, and CCF tests were performed on a TC6 compressor blade to analyze fatigue life characteristics. Results showed that CCF could significantly shorten blade life compared with pure LCF and that larger HCF caused more significant fatigue life reduction. Fatigue source characteristics and CCF fracture appearance were observed and analyzed using a scanning electron microscope (SEM).

Surface integrity generated with peripheral milling and the effect on low-cycle fatigue performance of aeronautic titanium alloy Ti-6Al-4V

2017 ◽  
Vol 122 (1248) ◽  
pp. 316-332 ◽  
Author(s):  
D. Yang ◽  
Z. Liu
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Surface Integrity ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Micro Hardness

ABSTRACTMachining-induced surface integrity has an important effect on reliability and service life of the components used in the aerospace industry where titanium alloy Ti-6Al-4V is widely applied. Characterisation of machining-induced surface integrity and revealing its effect on fatigue life are conducive to structural fatigue life optimisation design. In the present study, surface topography, residual stress, microstructure and micro-hardness were first characterised in peripheral milling of titanium alloy Ti-6Al-4V. Then, low-cycle fatigue performances of machined specimens were investigated on the basis of the tension-tension tests. Finally, the effects of surface integrity factors (stress concentration factor, residual stress and micro-hardness) on fatigue performances were discussed. Results show that stress concentration can reduce the fatigue life while increasing the residual compressive stress, and micro-hardness is beneficial to prolonging the fatigue life, but when the surface material of the specimen is subjected to plastic deformation due to yield, the residual stress on the surface is relaxed, and the effect on the fatigue performance is disappeared. Under the condition of residual stress relaxation, the stress concentration factor is the main factor to determine the low-cycle fatigue life of titanium alloy Ti-6Al-4V. While for the specimens with no residual stress relaxation, micro-hardness was the key factor to affect the fatigue life, followed by residual stress and stress concentration factor, respectively.

scholarly journals Effects of Machined Surface Integrity on High-Temperature Low-Cycle Fatigue Life and Process Parameters Optimization of Turning Superalloy Inconel 718

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2428
Author(s):  
Xiaoping Ren ◽  
Zhanqiang Liu ◽  
Xiaoliang Liang ◽  
Pengcheng Cui
Keyword(s):  
Residual Stress ◽  
High Temperature ◽  
Fatigue Life ◽  
Process Parameters ◽  
Surface Integrity ◽  
Inconel 718 ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Machined Surface ◽  
Machined Surface Integrity

Machined surface integrity characteristics, including surface stresses, physical-mechanical properties and metallographic structures, play important roles in the fatigue performance of machined components. This work aimed at investigating the effects of machined surface integrity on high-temperature low-cycle fatigue life. The process parameters were optimized to obtain required surface integrity and fatigue life of the turning superalloy Inconel 718. The relationships between low-cycle fatigue life and machined surface integrity characterization parameters were established based on the low-cycle fatigue tests at a high temperature (650 °C). The sensitivities of turning process parameters to high-temperature low-cycle fatigue life were analyzed, and the optimization parameters were proposed with the goal of antifatigue manufacturing. Experimental results indicated that the impact order of the characterization parameters of machined surface integrity on the high-temperature low-cycle fatigue life were the degree of work hardening RHV, the residual stress in the cutting speed direction S22, the fatigue stress concentration factor Kf, the degree of grain refinement RD and the residual stress in the feed direction S33. In the range of turning parameters of the experiments in this research, the cutting speeds could be 80~110 m/min, and the feed rate could be 0.10~0.12 mm/rev to achieve a longer high-temperature low-cycle fatigue life. The results can be used for guiding the fatigue-resistant manufacturing research of aeroengine superalloy turbine disks.

Fatigue Performance of Copper Alloys in Seawater Environment

2013 ◽  
Vol 577-578 ◽  
pp. 261-264
Author(s):  
Jochen Aufrecht ◽  
Andrew Drach ◽  
Adolf Grohbauer ◽  
Uwe Hofmann ◽  
Stefan Theobald ◽  
...  
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Copper Alloys ◽  
Fatigue Performance ◽  
Natural Seawater ◽  
Rectangular Plates ◽  
Cycle Fatigue ◽  
Seawater Environment

Corrosion fatigue performance of two copper alloys (admiralty brass and cupronickel 90/10) is investigated by conducting fatigue tests in artificial seawater. Two different experimental setups are developed and used: immersed rotating beam bending of round wires and immersed flexural cycling of rectangular plates. For the second setup, two sets of specimens are used: as-manufactured and after 1-year exposure to natural seawater in North Atlantic. In addition, the fatigue performance is compared between the dry and immersed tests. It is observed that the fatigue life of copper alloys in seawater environment depends on their composition and manufacturing parameters. Immersion in seawater does not affect low-cycle fatigue, however, high-cycle fatigue behavior shows significant differences. It is also observed that one-year preliminary exposure to natural seawater (stress-free corrosion) results in up to three times reduction of fatigue life at stress amplitudes corresponding to high-cycle fatigue.

On low cycle fatigue life of nickel-based superalloy valve membranes under non-proportional cyclic loading

2008 ◽  
Vol 30 (7) ◽  
pp. 1160-1168 ◽  
Author(s):  
M ABBADI ◽  
S BELOUETTAR ◽  
P MUZZO ◽  
P KREMER ◽  
O OUSSOUADDI ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Cyclic Loading ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Nickel Based Superalloy

Low-Cycle Fatigue of Nickel-Based Superalloy Hastelloy X at Elevated Temperatures

2001 ◽  
Author(s):  
Lijia Chen ◽  
Peter K. Liaw ◽  
Robert L. McDaniels ◽  
James W. Blust ◽  
Paul F. Browning ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Stress Relaxation ◽  
Test Temperature ◽  
Low Cycle Fatigue ◽  
Hold Time ◽  
Cyclic Hardening ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Hastelloy X ◽  
Nickel Based Superalloy

The fully-reversed total strain-controlled low-cycle fatigue tests with and without hold times, as well as stress-relaxation tests, were conducted at 816°C and 927°C in laboratory air on a nickel-based superalloy, HASTELLOY X. The influence of temperatures and hold times on low-cycle fatigue behavior of the alloy was investigated. At both temperatures of 816°C and 927°C, the alloy exhibited initial cyclic hardening, followed by a saturated cyclic stress response or cyclic softening under low-cycle fatigue without hold times. For low-cycle fatigue tests with hold times, however, the alloy showed either cyclic hardening or cyclic stability, which is closely related to the test temperature and the duration of the hold time. It was also observed that the low-cycle fatigue life of the alloy considerably decreased due to the introduction of strain hold times. Generally, a longer hold time would result in a greater reduction in the fatigue life. However, for the tests without hold times, the test temperature seems to have little influence on the fatigue life of the alloy at the test temperatures used in this investigation. The stress relaxation tests show that at the beginning of strain hold, the stress drops very quickly and then decreases very slowly with prolonging time. In addition, the fracture surfaces of the fatigued specimens were observed using scanning electron microscopy to determine the crack initiation and propagation modes. The fatigue life was predicted by the frequency modified tensile hysteresis energy method. The predicted lives were found to be in good agreement with the experiment results.

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