Microscopic Damage Mechanism of Nickel-Based Superalloy Inconel 738LC Under Creep-Fatigue Conditions

2000 ◽  
Vol 122 (3) ◽  
pp. 315-320 ◽  
Author(s):  
Masato Yamamoto ◽  
Takashi Ogata
Keyword(s):  
Fatigue Life ◽  
Grain Boundary ◽  
Life Prediction ◽  
Grain Boundary Sliding ◽  
Fatigue Tests ◽  
Creep Fatigue ◽  
Boundary Sliding ◽  
Inconel 738Lc ◽  
Life Prediction Model

Creep-fatigue damage in Inconel 738LC was clarified by in-situ observation and a new creep-fatigue life prediction model was proposed based on the mechanism identified. Creep-fatigue tests on standard specimens show that the tensile hold creep-fatigue lives were reduced to 60 to 80 percent and those in the compressive hold condition were reduced to 20 to 40 percent of the fatigue life of the same total strain condition. In-situ creep-fatigue tests on miniature specimens show that grain boundary sliding could be observed under the compressive strain hold condition and under the tensile strain hold condition grain boundary cavity damage and grain boundary sliding were observed. These mechanisms are regarded as the main cause of the damage acceleration under the creep-fatigue loading conditions. Therefore, the new creep-fatigue life prediction model, which is based on the nonlinear damage accumulation method, employed two damage acceleration parameters “dsl” and “dcr,” which represent grain boundary sliding damage and grain boundary cavity damage, respectively. Creep-fatigue lives of the test results were well predicted by the proposed model. [S0094-4289(00)01203-2]

Thermo-Mechanical Fatigue of Mar-M247: Part 1—Experiments

1990 ◽  
Vol 112 (1) ◽  
pp. 68-79 ◽  
Author(s):  
D. A. Boismier ◽  
Huseyin Sehitoglu
Keyword(s):  
Grain Boundary ◽  
Prediction Model ◽  
Life Prediction ◽  
Crack Nucleation ◽  
Mechanical Tests ◽  
Fatigue Tests ◽  
Boundary Crack ◽  
Mechanical Fatigue ◽  
Nickel Based Superalloy ◽  
Life Prediction Model

Isothermal fatigue tests, out-of-phase and in-phase thermo-mechanical fatigue tests were performed on Mar-M247 nickel-based superalloy. The experiments were conducted in the temperature range 500°C to 871°C. Results indicate that the lives differ with strain-temperature phasing and with strain rate. The results of out-of-phase thermo-mechanical tests correspond well with strain-life data of isothermal tests conducted at the peak temperature (871°C). However, the in-phase thermo-mechanical results differed depending on the strain amplitude. Significant surface and crack tip oxidation and gamma prime depletion has been observed based on metallographic and Auger Spectroscopic analyses. These changes were measured as a function of time. The environment induced changes significantly influenced the fatigue lives in isothermal and out-of-phase thermo-mechanical fatigue cases. In these cases transgranular cracking was observed. Grain boundary crack nucleation and grain boundary crack growth dominated the in-phase thermo-mechanical fatigue cases. Based on these observations the requirements for a life prediction model are outlined. The life prediction model and the predictions are given in Part 2 of this paper.

In-situ observation of cooperative grain boundary sliding and migration in the nano-twinned nanocrystalline-Au thin-films

2020 ◽  
Vol 180 ◽  
pp. 97-102 ◽  
Author(s):  
Qizhen Li ◽  
Lihua Wang ◽  
Jiao Teng ◽  
Xiaolu Pang ◽  
Xiaodong Han ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Boundary ◽  
Grain Boundary Sliding ◽  
In Situ Observation ◽  
Boundary Sliding ◽  
Au Thin Films ◽  
And Migration

Tribological Behavior of Mg-Mg2Si In Situ Composite

2012 ◽  
Vol 710 ◽  
pp. 401-406
Author(s):  
Kumaraswamy Kaliamma Ajith Kumar ◽  
Uma Thanu Subramonia Pillai ◽  
Bellambettu Chandrasekhara Pai ◽  
Madhusudan Chakraborty
Keyword(s):  
Elevated Temperature ◽  
Wear Rate ◽  
Grain Boundary ◽  
Tribological Behavior ◽  
Grain Boundary Sliding ◽  
Dry Sliding ◽  
Boundary Sliding ◽  
Si Content ◽  
State Processing

Mg-Mg2Si in-situ composites by the addition of Si in Mg have become more attractive since the Mg2Si phase impedes the grain boundary sliding at elevated temperature because of its inherent properties which greatly improve the heat and wear resistances. In the present work, Mg-Mg2Si composites have been prepared by the liquid state processing with different amount of silicon additions. The microstructure and dry sliding tribological behavior of the composites have been studied. SEM studies reveal the wear mechanisms involved in these composites. The results indicate that wear rate of the composites is a function of Mg2Si content in the composite. The effect of Mg2Si morphology and distribution on the overall mechanism is also discussed.

A creep-fatigue life prediction model considering multi-factor coupling effect

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Junzhou Huo ◽  
Debin Sun ◽  
Shaoxia An
Keyword(s):  
Fatigue Life ◽  
Prediction Model ◽  
Life Prediction ◽  
Evaluation Method ◽  
Prediction Models ◽  
Coupling Effect ◽  
Fatigue Life Prediction ◽  
Creep Fatigue ◽  
Exhaustion Method ◽  
Life Prediction Model

Abstract A creep-fatigue life prediction model based on a novel creep damage evaluation method (NCDEM) considering the multi-factor coupling effect is presented in this paper. Further, to verify the validity and practicability, the creep-fatigue life of GH4169 at 650 °C is calculated to compare with the experimental results. Ultimately, the prediction results are respectively compared with those of the creep-fatigue life prediction models based on the time fraction method (TFM), ductility exhaustion method (DEM), and strain energy density exhaustion method (SEDEM). Consequently, the prediction results are distributed in ±1.5 times dispersion band, which elucidates the creep-fatigue life prediction model proposed based on the NCDEM has the best ability.

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