scholarly journals Creep-fatigue interaction in heat resistant austenitic alloys

2018 ◽  
Vol 165 ◽  
pp. 05001 ◽  
Author(s):  
Hugo Wärner ◽  
Mattias Calmunger ◽  
Guocai Chai ◽  
Johan Moverare
Keyword(s):  
Fatigue Life ◽  
Dwell Time ◽  
Mechanical Test ◽  
Testing Temperature ◽  
Austenitic Steels ◽  
Maximum Strain ◽  
Specific Test ◽  
Austenitic Alloys ◽  
Creep Fatigue ◽  
The Given

This work includes an investigation of two commercial austenitic steels: UNS S21500 (Esshete 1250) and UNS S31035 (Sandvik SanicroTM 25). The materials were exposed to isothermal strain controlled fatigue with load controlled dwell time at maximum strain. The testing temperature used was 700°C and the test cycles were performed in tension. Mechanical test data were obtained and analysed in order to define creep-fatigue damage diagrams at failure for the investigated austenitic alloys. During the given conditions, Sanicro 25 showed superior creep-fatigue life, suffered less amount of creep elongation for the same amount of strain amplitude and dwell times compared to Esshete 1250. Both alloys showed creep-fatigue interaction damage for specific test configurations.

An Interpretation of Axial Creep-Fatigue Damage Interaction in Type 316 Stainless Steel (Survey Paper)

1990 ◽  
Vol 112 (1) ◽  
pp. 4-19 ◽  
Author(s):  
S. Y. Zamrik
Keyword(s):  
Life Prediction ◽  
Dwell Time ◽  
Austenitic Steels ◽  
Relaxation Data ◽  
Damage Mechanisms ◽  
Survey Paper ◽  
Long Period ◽  
Strain Limit ◽  
Creep Fatigue ◽  
Summation Rule

Creep-fatigue interaction and its effect on damage of components in service have been a major concern to analysts. To deal with this problem, several criteria have been proposed and used, such as: cycle-time fraction summation rule, strain limit, fracture maps where damage mechanisms are based on crack initiation or propagation, and ductility exhaustion. These concepts are reviewed in this paper so that one can interpret the damage mechanisms caused by creep and by fatigue. If a long period of dwell-time at elevated temperature is imposed on a component under strain conditions, stress relaxation occurs. Relaxation data can be used, for example, in austenitic steels, in predicting creep stages; however, interpretation of data obtained from such tests could be misleading in assessing damage. An example is given for life prediction on the basis of two selected criteria: the fraction rule and ductility exhaustion.

An Abnormal Increase of Fatigue Life with Dwell Time during Creep-Fatigue Deformation for Directionally Solidified Ni-Based Superalloy DZ445

2018 ◽  
Vol 37 (3) ◽  
pp. 277-284 ◽  
Author(s):  
Biao Ding ◽  
Weili Ren ◽  
Kang Deng ◽  
Haitao Li ◽  
Yongchun Liang
Keyword(s):  
Fatigue Life ◽  
Hysteresis Loop ◽  
Dwell Time ◽  
Fatigue Behavior ◽  
Maximum Energy ◽  
Abnormal Behavior ◽  
Directionally Solidified ◽  
Creep Fatigue ◽  
Abnormal Increase ◽  
Fatigue Deformation

AbstractThe paper investigated the creep-fatigue behavior for directionally solidified nickel-based superalloy DZ445 at 900 °C. It is found that the fatigue life shows an abnormal increase when the dwell time exceeds a critical value during creep-fatigue deformation. The area of hysteresis loop and fractograph explain the phenomenon quite well. The shortest life corresponds to the maximal area of hysteresis loop, i. e. the maximum energy to be consumed during the creep-fatigue cycle. The fractographic observation of failed samples further supports the abnormal behavior of fatigue life.

Effect of dwell time on creep-fatigue life of a high-Nb TiAl alloy at 750°C

2015 ◽  
Vol 109 ◽  
pp. 61-63 ◽  
Author(s):  
Long Yu ◽  
Xiping Song ◽  
Li You ◽  
Zehui Jiao ◽  
Huichen Yu
Keyword(s):  
Fatigue Life ◽  
Dwell Time ◽  
Tial Alloy ◽  
Creep Fatigue

The Influence of Dwell Time on Low Cycle Fatigue Behavior of Ni-base Superalloy IC10

2017 ◽  
Vol 36 (8) ◽  
pp. 795-803
Author(s):  
Anqiang Wang ◽  
Lu Liu ◽  
Zhixun Wen ◽  
Zhenwei Li ◽  
Zhufeng Yue
Keyword(s):  
Fatigue Life ◽  
Dwell Time ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Dislocation Line ◽  
Reverse Direction ◽  
Structure Evolution ◽  
Cycle Fatigue ◽  
Creep Fatigue ◽  
Base Superalloy

AbstractLow cycle fatigue and creep-fatigue experiments of IC10 Ni-base superalloy plate specimens with multiple holes were performed below 1,000 °C. The average fatigue life is 105.4 cycles, while the creep-fatigue life is 103.4 cycles, which shows that the life of creep-fatigue is reduced 1–2 times compared with low cycle fatigue life. After tests, the detailed fracture and microscopic structure evolution were observed by scanning electron microscopy (SEM); meanwhile, the constitutive model based on crystal plasticity theory was established and the fracture mechanism was analyzed. Three conclusions have been obtained: First, the load during dwell time leads to the damage accumulation caused by deformation and the interaction of fatigue and creep shortens the service life of materials seriously. Second, in order to maintain the macroscopic deformation, a new slip plane starts to makes the dislocation slide in reverse direction, which leads to fatigue damage and initial cracks. Third, the inner free surface creates opportunities for escape of the dislocation line, which is caused by the cavity. What’s more, the cure dislocation generated by cyclic loading contributes to the formation and growth of cavities.

scholarly journals Characterization of Austenitic Stainless Steels with Regard to Environmentally Assisted Fatigue in Simulated Light Water Reactor Conditions

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 307
Author(s):  
Matthias Bruchhausen ◽  
Gintautas Dundulis ◽  
Alec McLennan ◽  
Sergio Arrieta ◽  
Tim Austin ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Elevated Temperature ◽  
Strain Rate ◽  
Power Plants ◽  
Research Effort ◽  
Hold Time ◽  
Strain Range ◽  
Austenitic Steels ◽  
Mean Strain

A substantial amount of research effort has been applied to the field of environmentally assisted fatigue (EAF) due to the requirement to account for the EAF behaviour of metals for existing and new build nuclear power plants. We present the results of the European project INcreasing Safety in NPPs by Covering Gaps in Environmental Fatigue Assessment (INCEFA-PLUS), during which the sensitivities of strain range, environment, surface roughness, mean strain and hold times, as well as their interactions on the fatigue life of austenitic steels has been characterized. The project included a test campaign, during which more than 250 fatigue tests were performed. The tests did not reveal a significant effect of mean strain or hold time on fatigue life. An empirical model describing the fatigue life as a function of strain rate, environment and surface roughness is developed. There is evidence for statistically significant interaction effects between surface roughness and the environment, as well as between surface roughness and strain range. However, their impact on fatigue life is so small that they are not practically relevant and can in most cases be neglected. Reducing the environmental impact on fatigue life by modifying the temperature or strain rate leads to an increase of the fatigue life in agreement with predictions based on NUREG/CR-6909. A limited sub-programme on the sensitivity of hold times at elevated temperature at zero force conditions and at elevated temperature did not show the beneficial effect on fatigue life found in another study.

Experimental and numerical investigation of the thermomechanical load on a turbine housing in a radial turbocharger

2021 ◽  
pp. 095440702110521
Author(s):  
Shaolin Chen ◽  
Hong Zhang ◽  
Liaoping Hu ◽  
Guangqing He ◽  
Fen Lei ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Fatigue Life ◽  
Simulation Analysis ◽  
Simulation Method ◽  
Testing Temperature ◽  
Experimental Results ◽  
Maximum Temperature ◽  
Monitoring Point ◽  
Turbine Housing

The fatigue life of turbine housing is an important index to measure the reliability of a radial turbocharger. The increase in turbine inlet temperatures in the last few years has resulted in a decrease in the fatigue life of turbine housing. A simulation method and experimental verification are required to predict the life of a turbine housing in the early design and development process precisely. The temperature field distribution of the turbine housing is calculated using the steady-state bidirectional coupled conjugate heat transfer method. Next, the temperature field results are considered as the boundary for calculating the turbine housing temperature and thermomechanical strain, and then, the thermomechanical strain of the turbine housing is determined. Infrared and digital image correlations are used to measure the turbine housing surface temperature and total thermomechanical strain. Compared to the numerical solution, the maximum temperature RMS (Root Mean Square) error of the monitoring point in the monitoring area is only 3.5%; the maximum strain RMS error reached 11%. Experimental results of temperature field test and strain measurement test show that the testing temperature and total strain results are approximately equal to the solution of the numerical simulation. Based on the comparison between the numerical calculation and experimental results, the numerical simulation and test results were found to be in good agreement. The experimental and simulation results of this method can be used as the temperature and strain (stress) boundaries for subsequent thermomechanical fatigue (TMF) simulation analysis of the turbine housing.

scholarly journals A Concise Binomial Model for Nonlinear Creep-Fatigue Crack Growth Behavior at Elevated Temperatures

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 651
Author(s):  
Jianxing Mao ◽  
Zhixing Xiao ◽  
Dianyin Hu ◽  
Xiaojun Guo ◽  
Rongqiao Wang
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Dwell Time ◽  
Elevated Temperatures ◽  
Nonlinear Creep ◽  
Nickel Based Superalloy ◽  
Proposed Model ◽  
Creep Fatigue ◽  
Creep Fatigue Crack

The creep-fatigue crack growth problem remains challenging since materials exhibit different linear and nonlinear behaviors depending on the environmental and loading conditions. In this paper, we systematically carried out a series of creep-fatigue crack growth experiments to evaluate the influence from temperature, stress ratio, and dwell time for the nickel-based superalloy GH4720Li. A transition from coupled fatigue-dominated fracture to creep-dominated fracture was observed with the increase of dwell time at 600 °C, while only the creep-dominated fracture existed at 700 °C, regardless of the dwell time. A concise binomial crack growth model was constructed on the basis of existing phenomenal models, where the linear terms are included to express the behavior under pure creep loading, and the nonlinear terms were introduced to represent the behavior near the fracture toughness and during the creep-fatigue interaction. Through the model implementation and validation of the proposed model, the correlation coefficient is higher than 0.9 on ten out of twelve sets of experimental data, revealing the accuracy of the proposed model. This work contributes to an enrichment of creep-fatigue crack growth data in the typical nickel-based superalloy at elevated temperatures and could be referable in the modeling for damage tolerance assessment of turbine disks.

scholarly journals FATIGUE LIFE ANALYSIS OF RAMP DOOR FERRY RO-RO GT 1500 USING FINITE ELEMENT METHOD

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Alamsyah Alam ◽  
A. B. Mapangandro ◽  
Amalia Ika W ◽  
M U Pawara
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Life ◽  
Maximum Stress ◽  
Structural Integrity ◽  
Load Cycle ◽  
Point Load ◽  
Fatigue Life Analysis ◽  
The Given ◽  
Element Method

Ro - Ro Ferry is equipped with a connecting door between the port and the ship. The ramp door experiences load during loading and discharging of the rolling cargo. This repetitive load may cause fatigue failure. The structure of the ramp door should withstand this load. Therefore, The ramp door should be properly designed to ensure the structural integrity of the ramp door. The purpose of this research is to analyze the maximum stress and the Fatigue life of the bow ramp door. The method used is the finite element method. The given loads are several types of vehicles that are commonly transported by the ship. The given load case is the point load working at the girder plate and between the girder plate. Based on the simulation results with the given point load, the maximum stress is identified located between the girder for the large truck case with 397.02 MPa, while the minimum stress located at the girder for sedan car with 43.93 MPa. As for the fatigue life of the bow ramp door construction. it is 1.17 ~ 398.64 years, and the load cycle is 5.35 x 104 ~ 9.05 x 106 cycle. Keywords : Bow Ramp Door; Stress; Fatigue Life; Finite Element; Ferry

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