Coating Effects on Crack Growth in a Single Crystal Nickel Based Alloy During Thermo-Hechanical Fatigue

2009 ◽  
pp. 82-82-14 ◽  
Author(s):  
J Bressers ◽  
JM Martinez-Esnaola ◽  
A Martin-Meizoso ◽  
J Timm ◽  
M Arana-Antelo
Keyword(s):  
Single Crystal ◽  
Crack Growth ◽  
Nickel Based Alloy

Creep and damage of a Re/Ru-containing single crystal nickel-based alloy at high temperature

2021 ◽  
Vol 808 ◽  
pp. 140870
Author(s):  
Huajin Yan ◽  
Sugui Tian ◽  
Guoqi Zhao ◽  
Ning Tian ◽  
Shunke Zhang
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Nickel Based Alloy

scholarly journals Molecular Dynamics Simulation of Crack Propagation in Single-Crystal Aluminum Plate with Central Cracks

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Jun Ding ◽  
Lu-sheng Wang ◽  
Kun Song ◽  
Bo Liu ◽  
Xia Huang
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Crack Propagation ◽  
Strain Rate ◽  
Single Crystal ◽  
Crack Length ◽  
Crack Growth ◽  
Plastic Yield ◽  
Model Size ◽  
Dislocation Multiplication

The crack propagation process in single-crystal aluminum plate (SCAP) with central cracks under tensile load was simulated by molecular dynamics method. Further, the effects of model size, crack length, temperature, and strain rate on strength of SCAP and crack growth were comprehensively investigated. The results showed that, with the increase of the model size, crack length, and strain rate, the plastic yield point of SCAP occurred in advance, the limit stress of plastic yield decreased, and the plastic deformability of material increased, but the temperature had less effect and sensitivity on the strength and crack propagation of SCAP. The model size affected the plastic deformation and crack growth of the material. Specifically, at small scale, the plastic deformation and crack propagation in SCAP are mainly affected through dislocation multiplication and slip. However, the plastic deformation and crack propagation are obviously affected by dislocation multiplication and twinning in larger scale.

Estimation of Applied Stress at Fatigue Cracks of a Single Crystal Superalloy

2020 ◽  
Author(s):  
Daisuke Kobayashi ◽  
Katsuhiro Takama ◽  
Tomihiko Ikeda
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Fracture Surface ◽  
Single Crystal ◽  
Crack Growth ◽  
Applied Stress ◽  
Fatigue Crack Growth Rate ◽  
Single Crystal Superalloy

Abstract Needless to say, it is important to estimate the stress applied to a material when conducting failure analysis. In recent years, a material assessment method using electron back-scatter diffraction (EBSD) has been developed. It has been reported that a characteristic misorientation distribution corresponding to the fracture mode is seen in cross-sectional EBSD observation near the fracture surface of a Ni-based superalloy. Furthermore, the authors discovered EBSD striations on the crack cross-section, which is formed with each fatigue crack growth during a turbine shut-down process. This was discovered in misorientation analysis on a single-crystal superalloy blade used in a commercial land-based gas turbine. Since Ni-based superalloys have high deformation resistance, they do not undergo enough ductile deformation to form striations at the crack tip on the fracture surface during fatigue crack growth, and, as a result, striations corresponding to cyclic loadings are rarely observed in fractography. Even in such a Ni-based superalloy with brittle crack growth, the fatigue crack growth rate and the applied stress can be estimated by measuring EBSD striation spacing in misorientation analysis. However, a practical problem in assessment is that the resolution limit fixed with field emission scanning electron microscopes (FE-SEM) determine the range in which crack growth rate can be assessed. Hence, it is difficult to clearly discriminate the EBSD striations when the fatigue crack growth rate is too low, such as in the low stress intensity factor range (ΔK) region. The applied stress can be calculated from ΔK. Therefore, in this paper, in order to estimate the applied stress during fatigue crack growth, we focused on estimating ΔK by measuring the plastic zone size along the crack growth.

Oxidation-Assisted Crack Growth in Single-Crystal Superalloys during Fatigue with Compressive Holds

2017 ◽  
Vol 49 (1) ◽  
pp. 105-116 ◽  
Author(s):  
M. A. Lafata ◽  
L. H. Rettberg ◽  
M. Y. He ◽  
T. M. Pollock
Keyword(s):  
Single Crystal ◽  
Crack Growth

Crack Growth Prediction for Cracked Dissimilar Metal Weld Joint in Pipe Under Large Seismic Cyclic Loading

2018 ◽  
Author(s):  
Yoshihito Yamaguchi ◽  
Jinya Katsuyama ◽  
Yinsheng Li
Keyword(s):  
Risk Assessment ◽  
Crack Growth ◽  
Seismic Risk ◽  
Evaluation Method ◽  
Seismic Loading ◽  
Steel Pipes ◽  
Dissimilar Metal ◽  
Growth Evaluation ◽  
Nickel Based Alloy ◽  
Metal Weld

Seismic risk assessment of nuclear power plants (NPPs) based on seismic hazard and fragility analyses of structures/components has become important since Japanese NPPs have experienced several large earthquakes beyond the design basis ground motion. In addition, cracks resulting from the long-term operation of NPPs have been detected in piping system of NPPs. For example, in the pressurized water reactor environment, crack initiation and propagation due to primary water stress corrosion cracking (PWSCC) have been observed in dissimilar metal welds made of nickel-based alloy. Therefore, fragility analyses related to seismic probabilistic risk assessment considering such PWSCC and seismic loading are important for more realistic seismic risk assessment. In our previous study, a fragility analysis method for cracked pipes that is applicable for the carbon and stainless steel pipes has been developed. The developed method consists of two functions for evaluating the crack growth due to seismic loading as well as the age-related degradation. Since the crack growth evaluation method is available for only carbon steel and stainless steel pipes, it is important to enhance the applicability of the method to dissimilar metal welds of pipes where the cracks due to PWSCC were observed. In this study, an extensive study for crack growth evaluation method is performed for the dissimilar metal welds. Here, applicability of the previously developed method to a nickel-based alloy weld is investigated. We performed crack growth tests using the center cracked plate specimens and welded pipe specimens with circumferential through-wall crack machined from dissimilar metal weld joint of pipes. It is found that the amount of crack growth predicted by our crack growth evaluation method are in good agreement with the experimental results. Therefore, we conclude that the previously developed method can be widely used for evaluating the crack growth behavior under seismic loading conditions in the nuclear piping including dissimilar metal welds of pipes.

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