scholarly journals Combined creep and hydrogen attack of petro refinery steel

1999 ◽  
Author(s):  
◽  
Andrew J. Baker
Keyword(s):  
Petrochemical Industry ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
High Tech ◽  
Continuum Damage ◽  
Hydrogen Attack ◽  
Creep Life ◽  
High Hydrogen ◽  
Uniaxial Creep ◽  
Testing Work

The thesis is based on the study of the interaction between creep and hydrogen attack, with particular emphasis on the commonly used 2.25Cr-lMo steel. The driving force for the work is the petrochemical industry, where large steel reactor vessels used for hydro-cracking and other processes, are known to suffer damage by hydrogen attack. Currently, no reliable method exists for determining the lifetime of these vessels, due partially to the difficulty of obtaining experimental data under the necessary' high hydrogen pressures and temperatures.A large part of the thesis involved the design and building of unique, high-tech testing facilities which could operate safely and accurately under the severe conditions required for such a study. The test rigs were then used to perform both simple uniaxial creep and internally pressurised tube tests in hydrogen environments. Pressurised tubes were used to provide a stress-state more closely related to that found in industrial components. Such experiments allow more accurate extrapolation to industrial pressure vessel behaviour than would be possible with uniaxial data alone.The creep results, together with careful metallography, showed the damaging effect of hydrogen attack on creep life and ductility, or conversely, the accelerating effect of applied stress on hydrogen attack. Tube testing revealed an effect of the multiaxial stress and demonstrated the importance of the hydrogen concentration in the steel.The above results were used to develop a Continuum Damage Mechanics (CDM) model for the prediction of tubular behaviour when pressurised with hydrogen. Within the range of conditions studied, the model was successful and further creep testing work is suggested to verify and develop the model further, as well as to study in greater detail the hydrogen attack mechanisms.

Volumetric Damage Modeling of High Temperature Hydrogen Attack in Steel Using a Continuum Damage Mechanics Approach

2020 ◽  
Author(s):  
K. E. Bagnoli ◽  
Z. A. Cater-Cyker ◽  
R. L. Holloman ◽  
C. A. Hay ◽  
S. Chavoshi ◽  
...  
Keyword(s):  
High Temperature ◽  
Damage Mechanics ◽  
Elevated Temperatures ◽  
Continuum Damage Mechanics ◽  
Service Evaluation ◽  
Process Equipment ◽  
Continuum Damage ◽  
Hydrogen Attack ◽  
High Hydrogen ◽  
Key Aspects

Abstract Hydrogen attack is a degradation phenomenon that affects process equipment operated at elevated temperatures in an environment containing a high hydrogen partial pressure. It has been the subject of numerous studies over the years prompted by damage discovered during routine inspections, or incidents that have occurred in service. As non-destructive evaluation (NDE) techniques have improved, damage is being detected during earlier stages where safe operation may still be possible for some time period. This work focuses on the fitness for service evaluation of equipment containing high temperature hydrogen attack (HTHA) using a continuum damage mechanics (CDM) approach. The model can be employed to assess the loss in load bearing capacity due to damage in the form of widespread micro-fissuring and voids (i.e. up to the point of macro-crack coalescence). Experimental data from literature sources have been used to develop a relationship between damage rate and operational loading conditions. The predictions are compared to field experience to illustrate key aspects of this approach.

Multixial Creep Life Prediction of Ceramic Structures Using Continuum Damage Mechanics and the Finite Element Method

1999 ◽  
Vol 121 (4) ◽  
pp. 577-585 ◽  
Author(s):  
O. M. Jadaan ◽  
L. M. Powers ◽  
J. P. Gyekenyesi
Keyword(s):  
Life Prediction ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Creep Rupture ◽  
Continuum Damage ◽  
Creep Life ◽  
Current State ◽  
Creep Life Prediction ◽  
Uniaxial Creep ◽  
Temperature Time

High temperature and long duration applications of monolithic ceramics can place their failure mode in the creep rupture regime. A previous model advanced by the authors described a methodology by which the creep rupture life of a loaded component can be predicted. That model was based on the life fraction damage accumulation rule in association with the modified Monkman-Grant creep rupture criterion. However, that model did not take into account the deteriorating state of the material due to creep damage (e.g., cavitation) as time elapsed. In addition, the material creep parameters used in that life prediction methodology, were based on uniaxial creep curves displaying primary and secondary creep behavior, with no tertiary regime. The objective of this paper is to present a creep life prediction methodology based on a modified form of the Kachanov-Rabotnov continuum damage mechanics (CDM) theory. In this theory, the uniaxial creep rate is described in terms of stress, temperature, time, and the current state of material damage. This scalar damage state parameter is basically an abstract measure of the current state of material damage due to creep deformation. The damage rate is assumed to vary with stress, temperature, time, and the current state of damage itself. Multiaxial creep and creep rupture formulations of the CDM approach are presented in this paper. Parameter estimation methodologies based on nonlinear regression analysis are also described for both, isothermal constant stress states and anisothermal variable stress conditions. This creep life prediction methodology was preliminarily added to the integrated design code named Ceramics Analysis and Reliability Evaluation of Structures/Creep (CARES/Creep), which is a postprocessor program to commercially available finite element analysis (FEA) packages. Two examples, showing comparisons between experimental and predicted creep lives of ceramic specimens, are used to demonstrate the viability of this methodology and the CARES/Creep program.

Creep Life Prediction of Aircraft Turbine Disc Alloy Using Continuum Damage Mechanics

2017 ◽  
Vol 38 (1) ◽  
pp. 25-30
Author(s):  
Yan-Feng Li ◽  
Zhisheng Zhang ◽  
Chenglin Zhang ◽  
Jie Zhou ◽  
Hong-Zhong Huang
Keyword(s):  
Numerical Analysis ◽  
Test Data ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Creep Model ◽  
Continuum Damage ◽  
Creep Life ◽  
Creep Life Prediction ◽  
Turbine Disc

Abstract This paper deals with the creep characteristics of the aircraft turbine disc material of nickel-base superalloy GH4169 under high temperature. From the perspective of continuum damage mechanics, a new creep life prediction model is proposed to predict the creep life of metallic materials under both uniaxial and multiaxial stress states. The creep test data of GH4169 under different loading conditions are used to demonstrate the proposed model. Moreover, from the perspective of numerical simulation, the test data with analysis results obtained by using the finite element analysis based on Graham creep model is carried out for comparison. The results show that numerical analysis results are in good agreement with experimental data. By incorporating the numerical analysis and continuum damage mechanics, it provides an effective way to accurately describe the creep damage process of GH4169.

scholarly journals Multiaxial Creep Life Prediction of Ceramic Structures Using Continuum Damage Mechanics and the Finite Element Method

1998 ◽  
Author(s):  
Osama M. Jadaan ◽  
Lynn M. Powers ◽  
John P. Gyekenyesi
Keyword(s):  
Life Prediction ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Creep Rupture ◽  
Creep Life ◽  
Current State ◽  
Creep Life Prediction ◽  
Uniaxial Creep ◽  
Multiaxial Creep ◽  
Temperature Time

High temperature and long duration applications of monolithic ceramics can place their failure mode in the creep rupture regime. A previous model advanced by the authors described a methodology by which the creep rupture life of a loaded component can be predicted. That model was based on the life fraction damage accumulation rule in association with the modified Monkman-Grant creep rupture criterion. However, that model did not take into account the deteriorating state of the material due to creep damage (e.g., cavitation) as time elapsed. In addition, the material creep parameters used in that life prediction methodology, were based on uniaxial creep curves displaying primary and secondary creep behavior, with no tertiary regime. The objective of this paper is to present a creep life prediction methodology based on a modified form of the Kachanov-Rabotnov continuum damage mechanics (CDM) theory. In this theory, the uniaxial creep rate is described in terms of stress, temperature, time, and the current state of material damage. This scalar damage state parameter is basically an abstract measure of the current state of material damage due to creep deformation. The damage rate is assumed to vary with stress, temperature, time, and the current state of damage itself. Multiaxial creep and creep rupture formulations of the CDM approach are presented in this paper. Parameter estimation methodologies based on nonlinear regression analysis are also described for both, isothermal constant stress states and anisothermal variable stress conditions This creep life prediction methodology was preliminarily added to the integrated design code. CARES/Creep (Ceramics Analysis and Reliability Evaluation of Structures/Creep), which is a postprocessor program to commercially available finite element analysis (FEA) packages. Two examples, showing comparisons between experimental and predicted creep lives of ceramic specimens, are used to demonstrate the viability of this methodology and the CARES/Creep program.

Continuum Damage Mechanics and Creep Life Analysis

1999 ◽  
Vol 67 (1) ◽  
pp. 193-196 ◽  
Author(s):  
G. J. Rodin
Keyword(s):  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Creep Life ◽  
Mechanics Model ◽  
Brittle Solids ◽  
Life Analysis

It is shown that the original continuum damage mechanics model of Kachanov is better suited for creep life analysis of creep-brittle solids and structures than continuum damage mechanics models that take into account damage-induced softening. [S0021-8936(00)03001-4]

Representation of uniaxial creep curves using continuum damage mechanics

1990 ◽  
Vol 32 (11) ◽  
pp. 945-957 ◽  
Author(s):  
F.P.E. Dunne ◽  
A.M. Othman ◽  
F.R. Hall ◽  
D.R. Hayhurst
Keyword(s):  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Uniaxial Creep ◽  
Creep Curves

scholarly journals Investigation on the validity of creep damage mechanics for the life time prediction of T92 welded joint

2019 ◽  
Vol 29 (3) ◽  
pp. 467-481 ◽  
Author(s):  
Xiao Wang ◽  
Xue Wang ◽  
Qiang Xu ◽  
Chuang Wang ◽  
Ya-lin Zhang ◽  
...  
Keyword(s):  
Damage Mechanics ◽  
Welded Joint ◽  
Rupture Life ◽  
Continuum Damage Mechanics ◽  
Creep Process ◽  
Continuum Damage ◽  
Creep Life ◽  
Fine Grained ◽  
Creep Time ◽  
The Continuum

This paper reports the damage evolution in ASME T92 welded joints during creep process. The creep test was conducted at 650℃ with applied stress of 90 MPa. The creep specimen was ultimately fractured at the fine-grained heat affected zones after creep for 1560 h. The metallographic results show that the cavity number and size in fine-grained heat affected zones increase with the creep time. The coalescence of creep cavities happened at the late stage of the creep life, which depending on the adjacent voids grows and propagates into the micro-crack. Besides, the deterioration in fine-grained heat affected zones of T92 steel welded joint with various creep time can be simulated based on the continuum damage mechanics with modified Kachanov-Rabotnov constitutive equation. The result of simulated creep rupture life is in good agreement with the experimental value, which indicates that the continuum damage mechanics can be used to predict creep life and evaluate creep deterioration in a T92 steel welded joint.

Creep Life Assessment of High Temperature Advanced Ultrasupercritical (AUSC) Conceptual Boiler Thick-Walled Pressure Components Using Continuum Damage Mechanics Approach

2016 ◽  
Author(s):  
B. Reddy Ganta ◽  
Monica Soare ◽  
Chen Shen
Keyword(s):  
High Temperature ◽  
Damage Mechanics ◽  
Base Material ◽  
Continuum Damage Mechanics ◽  
Life Assessment ◽  
Continuum Damage ◽  
Creep Life ◽  
Creep Properties ◽  
Design Life ◽  
Creep Life Assessment

Several nickel-based superalloys have been tested for high temperature applications for use in advanced ultra-supercritical (AUSC) fossil-fired power plants through laboratory and steam loops during the last several years. These materials include Inconel 740H and Haynes 282 which are found to have superior creep strength properties and be appropriate for use in the critical high pressure and high temperature (1400°F) AUSC boiler pressure parts such as superheater outlet header. While these materials have been extensively tested for their creep properties in laboratory test specimens, a real life design application with creep constitutive models is very limited. In this paper, development of a microstructure sensitive continuum damage mechanics (CDM) creep model for Haynes 282 base material that covers a wide range of stress levels and temperatures suitable for AUSC boiler design applications is described. Various creep mechanisms including diffusion and dislocation phenomena are included. This base material CDM model is then applied for a typical thick-walled high temperature header component and creep life assessment for the design life of the component is estimated. This analysis along with weldments and their creep properties still under development are considered crucial for identification of high creep damage regions in the component as well as proper design life assessment of the pressure parts.

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