scholarly journals Creep Damage Process and Rupture Time Prediction Methods of 2.25Cr-1Mo Steel Round Notch Bar Specimens

2021 ◽  
Vol 70 (2) ◽  
pp. 118-124
Author(s):  
Yuki SASAMOTO ◽  
Takashi OGATA
Keyword(s):  
Creep Damage ◽  
Rupture Time ◽  
Prediction Methods ◽  
Time Prediction ◽  
Damage Process

A Creep Rupture Time Model for Anisotropic Creep-Damage of Transversely-Isotropic Materials

2010 ◽  
Author(s):  
Calvin M. Stewart ◽  
Ali P. Gordon
Keyword(s):  
Damage Mechanics ◽  
Prediction Models ◽  
Creep Damage ◽  
Transversely Isotropic ◽  
Creep Rupture ◽  
Rupture Time ◽  
Time Model ◽  
Time Prediction ◽  
Transversely Isotropic Materials ◽  
Anisotropic Creep

Anisotropic creep-damage modeling has become an increasingly important prediction technique in both the aerospace and industrial gas turbine industries. The introduction of tensorial damage mechanics formulations in modeling tertiary creep behavior has lead to improved predictions of the creep strain that develops due to anisotropic grain structures and the induced anisotropy that occurs with intergranular damage. A number of isotropic creep-damage rupture time prediction models have been developed in literature; however, few rupture time prediction models for tensorial anisotropic creep-damage are available. In this paper, a rupture time model for anisotropic creep-damage of transversely isotropic materials is derived. Comparison with the Larson-Miller parameter, Monkman-Grant relation, and Kachanov-Rabotnov continuum damage mechanics (CDM) approach shows improved creep rupture time predictions for multiaxial conditions and material rotations. A parametric study of the rupture time predicted under various states of equivalent stress and material orientations is performed to demonstrate the robustness of the new formulation.

Atomic Diffusion Induced Damage of Ni-Base Super Alloy at Elevated Temperature

2016 ◽  
Author(s):  
Motoki Takahashi ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Power Plants ◽  
Creep Damage ◽  
Rotor Blades ◽  
Atomic Scale ◽  
Atomic Diffusion ◽  
Kernel Average Misorientation ◽  
Damage Process ◽  
Creep Loading ◽  
Ebsd Method ◽  
Base Superalloy

Ni-base superalloys consisting of binary phases such as cuboidal γ’ (Ni3Al) precipitates orderly dispersed in the γ matrix (Ni-rich matrix) have been generally used for rotor blades in energy power plants. However, fine dispersed γ’ precipitates are coarsened perpendicularly to the applied load direction during high temperature creep loading. As this phenomenon called “Rafting” proceeds, the strengthened micro texture disappears and then, cracks starts to grow rapidly along the boundaries of the layered texture. Thus, it is very important to evaluate the change of the crystallinity of the alloy in detail for explicating the atomic scale damage process. In this study, the change of the micro-texture of the Ni-base superalloy (CM247LC) was observed by using EBSD method. The change in the crystallinity was evaluated using both Kernel Average Misorientation (KAM) and image quality (IQ) values. The KAM value indicates the dislocation density and the IQ value shows the order of atom arrangement in the observed area. As a result, KAM value showed no significant change with increasing the creep damage. On the other hand, the IQ value monotonically shifted to lower values and the average IQ value gradually decreased as the creep loading time increased. Decreasing IQ value without change in KAM value implies that the density of point defects such as vacancies mainly increased under creep loading and ordered Ll2 structure became disordered. Therefore, the creep damage of this alloy is mainly dominated by not the accumulation of dislocations, but the increase in the disorder of atom arrangement in the micro texture caused by the diffusion of component elements.

scholarly journals The Creep-Damage Model of Salt Rock Based on Fractional Derivative

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2349 ◽  
Author(s):  
Hongwei Zhou ◽  
Di Liu ◽  
Gang Lei ◽  
Dongjie Xue ◽  
Yang Zhao
Keyword(s):  
Fractional Derivative ◽  
Creep Test ◽  
Damage Model ◽  
Creep Damage ◽  
Uniaxial Stress ◽  
Radioactive Waste Disposal ◽  
Creep Process ◽  
Salt Rock ◽  
Damage Process ◽  
Creep Damage Model

The use of salt rock for underground radioactive waste disposal facilities requires a comprehensive analysis of the creep-damage process in salt rock. A computer-controlled creep setup was employed to carry out a creep test of salt rock that lasted as long as 359 days under a constant uniaxial stress. The acoustic emission (AE) space-time evolution and energy-releasing characteristics during the creep test were studied in the meantime. A new creep-damage model is proposed on the basis of a fractional derivative by combining the AE statistical regularity. It indicates that the AE data in the non-decay creep process of salt rock can be divided into three stages. Furthermore, the authors propose a new creep-damage model of salt rock based on a fractional derivative. The parameters in the model were determined by the Quasi-Newton method. The fitting analysis suggests that the new creep-damage model provides a precise description of full creep regions in salt rock.

High Temperature Damage of Ni-Base Superalloy Caused by the Change of Microtexture due to the Strain-Induced Anisotropic Diffusion of Component Elements

2011 ◽  
Author(s):  
Hideo Miura ◽  
Ken Suzuki ◽  
Yamato Sasaki ◽  
Tomohiro Sano ◽  
Naokazu Murata
Keyword(s):  
High Temperature ◽  
Anisotropic Diffusion ◽  
Axial Strain ◽  
Creep Damage ◽  
Face Centered Cubic ◽  
Directional Coarsening ◽  
Damage Process ◽  
Temperature Damage ◽  
Face Centered ◽  
Base Superalloy

In order to assure the reliability of advanced gas turbine systems, it is very important to evaluate the damage of high temperature materials such as Ni-base superalloys under creep and fatigue conditions quantitatively. Since the micro texture of the gamma-prime (γ′) phase was found to vary during the creep damage process, it is possible, therefore, to evaluate the creep damage of this material quantitatively by measuring the change of the micro texture. The mechanism of the directional coarsening of γ′ phasesof Ni-base superalloy under uni-axial strain at high temperatures, which is called rafting, was analyzed by using molecular dynamics (MD) analysis. The stress-induced anisotropic diffusion of Al atoms perpendicular to the finely dispersed γ/γ′ interface in the superalloy was observed clearly in a Ni(001)/Ni3Al(001) interface structure. The stress-induced anisotropic diffusion was validated by experiment using the stacked thin films structures which consisted of the (001) face-centered cubic (FCC) interface. The reduction of the diffusion of Al atoms perpendicular to the interface is thus, effective for improving the creep and fatigue resistance of the alloy. It was also found by MD analysis that the dopant elements in the superalloy also affected the strain-induced diffusion of Al atoms. Both palladium and tantalum were effective elements which restrain Al atoms from moving around the interface under the applied stress, while titanium and tungsten accelerated the strain-induced anisotropic diffusion, and thus, the rafting phenomenon.

OS0804 EBSD Observation and Strain Evaluation on Creep Damage Process of SUS304HTB Steel

2012 ◽  
Vol 2012 (0) ◽  
pp. _OS0804-1_-_OS0804-3_
Author(s):  
Yoshiki MIZUTANI ◽  
Kazunari FUJIYAMA ◽  
Hirohisa KIMACHI
Keyword(s):  
Creep Damage ◽  
Damage Process

OS1438 EBSD Observation of Creep Damage Process in Ni-Cr-Co-Fe Alloy

2009 ◽  
Vol 2009 (0) ◽  
pp. 350-351
Author(s):  
Kazuto HIJIKURO ◽  
Kazunari FUJIYAMA ◽  
Hikaru NAKASEKO ◽  
Ryuichi ISHII ◽  
Takehisa HINO
Keyword(s):  
Creep Damage ◽  
Damage Process
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