Crack appearance of single-crystal nickel-base superalloys after thermomechanical fatigue failure

2009 ◽  
Vol 61 (12) ◽  
pp. 1105-1108 ◽  
Author(s):  
J.X. Zhang ◽  
H. Harada ◽  
Y. Koizumi ◽  
T. Kobayashi
Keyword(s):  
Single Crystal ◽  
Fatigue Failure ◽  
Thermomechanical Fatigue ◽  
Nickel Base Superalloys ◽  
Nickel Base

A continuum model for the creep of single crystal nickel-base superalloys

2005 ◽  
Vol 53 (3) ◽  
pp. 669-679 ◽  
Author(s):  
Sharat C. Prasad ◽  
I.J. Rao ◽  
K.R. Rajagopal
Keyword(s):  
Single Crystal ◽  
Continuum Model ◽  
Nickel Base Superalloys ◽  
Nickel Base

Anisotropic Life Prediction for Single Crystal Nickel-Base Flat Plate with a Hole

2014 ◽  
Vol 891-892 ◽  
pp. 1033-1038
Author(s):  
Cheng Li Dong ◽  
Hui Chen Yu ◽  
Ying Li
Keyword(s):  
Single Crystal ◽  
Flat Plate ◽  
Life Prediction ◽  
Failure Strain ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
The Finite Element Method ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Elastoplastic Constitutive Model

The material properties of single crystal (SC) superalloys are orientation-dependent. To fully exploit the material capacity, the life modeling needs to consider the anisotropy. In the present study the life modeling of SC nickel-base superalloys is considered by employing the modified Mücker's anisotropic theory in which a Hill type function is utilized for describing the anisotropic failure. Strain-controlled low cycle fatigue (LCF) experiments of SC nickel-base superalloys at different crystallographic orientations (i.e.[00, [01 and [11) under high temperatures (i.e.760°C) are carried out to verify the modeling availability for the modified Mücker's anisotropic theory. Further, based on the stress-strain field obtained by the anisotropic elastoplastic constitutive model coupled with the finite element method (FEM), the modified Mücker's anisotropic theory is employed to predict the fatigue life for SC flat plate with a hole.

A Life Prediction Model for Single-Crystal Nickel-Base Alloys Under Low-Cycle Fatigue

2020 ◽  
Author(s):  
Firat Irmak ◽  
Navindra Wijeyeratne ◽  
Taejun Yun ◽  
Ali Gordon
Keyword(s):  
Single Crystal ◽  
Gas Turbine ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Deformation Model ◽  
Cycle Fatigue ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Prediction Approach

Abstract In the development and assessment of critical gas turbine components, simulations have a crucial role. An accurate life prediction approach is needed to estimate lifespan of these components. Nickel base superalloys remain the material of choice for gas turbine blades in the energy industry. These blades are required to withstand both fatigue and creep at extreme temperatures during their usage time. Nickel-base superalloys present an excellent heat resistance at high temperatures. Presence of chromium in the chemical composition makes these alloys highly resistant to corrosion, which is critical for turbine blades. This study presents a flexible approach to combine creep and fatigue damages for a single crystal Nickel-base superalloy. Stress and strain states are used to compute life calculations, which makes this approach applicable for component level. The cumulative damage approach is utilized in this study, where dominant damage modes are capturing primary microstructural mechanism associated with failure. The total damage is divided into two distinctive modules: fatigue and creep. Flexibility is imparted to the model through its ability to emphasize the dominant damage mechanism which may vary among alloys. Fatigue module is governed by a modified version of Coffin-Manson and Basquin model, which captures the orientation dependence of the candidate material. Additionally, Robinson’s creep rupture model is applied to predict creep damage in this study. A novel crystal visco-plasticity (CVP) model is used to simulate deformation of the alloy under several different types of loading. This model has capability to illustrate the temperature-, rate-, orientation-, and history-dependence of the material. A user defined material (usermat) is created to be used in ANSYS APDL 19.0, where the CVP model is applied by User Programmable Feature (UPF). This deformation model is constructed of a flow rule and internal state variables, where the kinematic hardening phenomena is captured by back stress. Octahedral, cubic and cross slip systems are included to perform simulations in different orientations. An implicit integration process that uses Newton-Raphson iteration scheme is utilized to calculate the desired solutions. Several tensile, low-cycle fatigue (LCF) and creep experiments were conducted to inform modeling parameters for the life prediction and the CVP models.

Weld metal cracking in laser beam welded single crystal nickel base superalloys

2009 ◽  
Vol 25 (1) ◽  
pp. 68-75 ◽  
Author(s):  
Y. L. Wang ◽  
O. A. Ojo ◽  
R. G. Ding ◽  
M. C. Chaturvedi
Keyword(s):  
Laser Beam ◽  
Weld Metal ◽  
Single Crystal ◽  
Nickel Base Superalloys ◽  
Nickel Base
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