scholarly journals Orientation Dependence of Low Cycle Fatigue Properties of a Ni-based Single Crystal Superalloy DD10

2018 ◽  
Vol 47 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Fan Zhidong ◽  
Li Ji ◽  
Wang Dong ◽  
Lou Langhong ◽  
Zhang Jian
Keyword(s):  
Single Crystal ◽  
Low Cycle Fatigue ◽  
Orientation Dependence ◽  
Single Crystal Superalloy ◽  
Fatigue Properties ◽  
Cycle Fatigue

scholarly journals Low-Cycle Fatigue Behaviour of a Ni-Based Single-Crystal Superalloy

2014 ◽  
Vol 891-892 ◽  
pp. 416-421 ◽  
Author(s):  
Mikael Segersäll ◽  
Johan Moverare ◽  
Daniel Leidermark ◽  
Kjell Simonsson
Keyword(s):  
Single Crystal ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Cyclic Hardening ◽  
Fatigue Behaviour ◽  
Single Crystal Superalloy ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Tension Compression Asymmetry

In this study, low-cycle fatigue (LCF) tests at 500 °C in the <001>, <011> and <111> directions have been performed for the Ni-based single-crystal superalloy MD2. All tests were carried out in strain control with Rε=-1. The <001> direction has the lowest stiffness of the three directions and also shows the best fatigue properties in this study followed by the <011> and <111> directions, respectively. It is well recognised that Ni-based single-crystal superalloys show a tension/compression asymmetry in yield strength and this study shows that a tension/compression asymmetry also is prevalent during LCF conditions. At mid-life, the <001> direction generally has a higher stress in tension than in compression, while the opposite is true for the <011> direction. For the <111> direction the asymmetry is found to be strain range dependent. The <011> and <111> directions show a cyclic hardening behaviour when comparing cyclic stress-strain curves with monotonic stress-strain curves. In addition, the <011> and <111> directions show a serrated yielding behaviour for a number of cycles while the yielding of the <001> direction is more stable.

The influence of orientation on the elastic and low cycle fatigue properties of several single crystal nickel base superalloys

1994 ◽  
Vol 29 (2) ◽  
pp. 147-153 ◽  
Author(s):  
S X Li ◽  
E G Ellison ◽  
D J Smith
Keyword(s):  
Single Crystal ◽  
Low Cycle Fatigue ◽  
Experimental Studies ◽  
Elastic Response ◽  
Fatigue Properties ◽  
Elastic Behaviour ◽  
Nickel Base Superalloy ◽  
Cycle Fatigue ◽  
Nickel Base Superalloys ◽  
Nickel Base

Experimental studies on the influences of orientation on the elastic behaviour at 20°C and 950°C and the low cycle fatigue creep properties at 950°C of the single crystal nickel base superalloy SRR99 are described. The elastic response at 20°C is found to be in good agreement with predictions from the properties of pure nickel. At 950°C the orientation dependence is shown to be well correlated with a simple orientation function, which is also found to be insensitive to temperature. Similar correlations are shown for the single crystal nickel base superalloys PWA1480 and RENE N4 at high temperatures. The low cycle fatigue properties for fully reversed strain controlled cycles of SRR99 are shown to be strongly dependent on crystal orientation. Similar results from earlier work for RENE N4 are also illustrated. It is shown that by modifying the applied total strain range to take into account the influence of orientation for elastic deformation, essentially orientation-independent low fatigue cycle curves for SRR99 and RENE N4 are obtained.

High-Temperature Fatigue Properties of Single Crystal Superalloys in Air and Hydrogen

2004 ◽  
Vol 126 (3) ◽  
pp. 590-603 ◽  
Author(s):  
N. K. Arakere
Keyword(s):  
Fatigue Life ◽  
Single Crystal ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Fatigue Data ◽  
Blade Tip ◽  
Pressure Hydrogen

Hot section components in high-performance aircraft and rocket engines are increasingly being made of single crystal nickel superalloys such as PWA1480, PWA1484, CMSX-4, and Rene N-4 as these materials provide superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over their polycrystalline counterparts. Fatigue failures in PWA1480 single crystal nickel-base superalloy turbine blades used in the space shuttle main engine fuel turbopump are discussed. During testing many turbine blades experienced stage II noncrystallographic fatigue cracks with multiple origins at the core leading edge radius and extending down the airfoil span along the core surface. The longer cracks transitioned from stage II fatigue to crystallographic stage I fatigue propagation, on octahedral planes. An investigation of crack depths on the population of blades as a function of secondary crystallographic orientation (β) revealed that for β=45+/−15 deg tip cracks arrested after some growth or did not initiate at all. Finite element analysis of stress response at the blade tip, as a function of primary and secondary crystal orientation, revealed that there are preferential β orientations for which crack growth is minimized at the blade tip. To assess blade fatigue life and durability extensive testing of uniaxial single crystal specimens with different orientations has been tested over a wide temperature range in air and hydrogen. A detailed analysis of the experimentally determined low cycle fatigue properties for PWA1480 and SC 7-14-6 single crystal materials as a function of specimen crystallographic orientation is presented at high temperature (75°F–1800°F) in high-pressure hydrogen and air. Fatigue failure parameters are investigated for low cycle fatigue data of single crystal material based on the shear stress amplitudes on the 24 octahedral and 6 cube slip systems for FCC single crystals. The max shear stress amplitude [Δτmax] on the slip planes reduces the scatter in the low cycle fatigue data and is found to be a good fatigue damage parameter, especially at elevated temperatures. The parameter Δτmax did not characterize the room temperature low cycle fatigue data in high-pressure hydrogen well because of the noncrystallographic eutectic failure mechanism activated by hydrogen at room temperature. Fatigue life equations are developed for various temperature ranges and environmental conditions based on power-law curve fits of the failure parameter with low cycle fatigue test data. These curve fits can be used for assessing blade fatigue life.

High Temperature Multiaxial Low Cycle Fatigue of CMSX-2 NI-Base Single Crystal Superalloy

1997 ◽  
Vol 119 (2) ◽  
pp. 153-160 ◽  
Author(s):  
Mitsuru Kanda ◽  
Masao Sakane ◽  
Masateru Ohnami ◽  
Tadashi Hasebe
Keyword(s):  
Single Crystal ◽  
Low Cycle Fatigue ◽  
Crack Opening ◽  
Equivalent Stress ◽  
Equivalent Strain ◽  
Fatigue Tests ◽  
Single Crystal Superalloy ◽  
Cycle Fatigue ◽  
Data Correlation ◽  
Opening Displacement

This paper describes studies of the tension-torsion multiaxial low cycle fatigue of CMSX-2 Ni-base single crystal superalloy. Tension-torsion low cycle fatigue tests were carried out at 1173K using CMSX-2 hollow cylinder specimens aligned with the {001} axis. Several multiaxial strain and stress parameters were applied to the experimental data to examine the suitability of the parameters to life prediction. All the strain parameters proposed so far gave a large scatter of the data correlation. Discrepant data correlation with the strain parameters resulted from the anisotropic stress response due to the crystallographic texture. Larger Mises equivalent stress was applied in torsion tests than in tension tests at the same Mises strain. However, Mises stress and the equivalent stress based on crack opening displacement gave a satisfactory data correlation. This study developed a new equivalent strain, taking account of the anisotropy of the elastic constants, which correlates the multiaxial low cycle fatigue data with a small scatter.

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