The Influence of Diffusion-Related Mechanisms in Limiting Oxide-Scale Failure

1995 ◽  
Vol 41 ◽  
pp. 137-156 ◽  
Author(s):  
Hugh E. Evans ◽  
John R. Nicholls ◽  
Stuart R.J. Saunders
Keyword(s):  
Oxide Scale ◽  
Scale Failure

Analysis of secondary oxide-scale failure at entry into the roll gap

2000 ◽  
Vol 31 (6) ◽  
pp. 1483-1490 ◽  
Author(s):  
M. Krzyzanowski ◽  
J. H. Beynon ◽  
C. M. Sellars
Keyword(s):  
Oxide Scale ◽  
Roll Gap ◽  
Scale Failure

Prediction of Mechanical Scale Failure – Current Status and Perspectives

2011 ◽  
Vol 696 ◽  
pp. 138-143 ◽  
Author(s):  
Michael Schütze ◽  
Mario Rudolphi
Keyword(s):  
Experimental Data ◽  
Oxide Scale ◽  
Satisfactory Agreement ◽  
Critical Strain ◽  
Defect Size ◽  
Current Status ◽  
Model Data ◽  
Model Concept ◽  
New Model ◽  
Scale Failure

A new model concept for predicting mechanical oxide scale failure is applied to Al2O3, Cr2O3, Fe3O4and NiO. The calculated critical strain values are plotted versus the physical defect size using a simplified version of the original h-w-concept. A limited number of experimental data existing in the literature were entered into the plots and yield satisfactory agreement with the model data. Future efforts should focus on extending the experimental data basis and converting these data into h-values for the model.

EFFECTS OF Dy ON THE MICROSTRUCTURE AND SPALLATION FAILURE OF THE ALUMINA SCALES GROWN ON NiAl

2010 ◽  
Vol 24 (15n16) ◽  
pp. 3149-3154 ◽  
Author(s):  
HONGBO GUO ◽  
XIAOYAN WANG ◽  
SHENGKAI GONG
Keyword(s):  
Oxide Scale ◽  
High Temperature Oxidation ◽  
Cyclic Oxidation ◽  
Alumina Scale ◽  
Alumina Scales ◽  
Coating Materials ◽  
Temperature Oxidation ◽  
Arc Melting ◽  
Nial Alloy ◽  
Scale Failure

NiAl has attracted increasing attentions because of its promising potential as protective coating materials for high temperature oxidation resistance. In this paper, Dysprosium ( Dy ) doped NiAl alloys were produced by arc melting. Cyclic oxidation of the alloys was carried out at 1200°C. The effects of Dy as a reactive element on the microstructure and failure of alumina scales on NiAl were investigated. For the melted alloy, Dy was mainly precipitated along the grain boundary and some within the grains in the form of DyNi 2 Al 3 phase. Compared to Al 2 O 3 scale formed on the undoped NiAl alloy, the microstructure of the scale was greatly changed and the ridge-like Al 2 O 3 scale became less distinct on Dy -doped NiAl . The equi-axed alumina scale grew on NiAl , whereas the columnar alumina developed on Dy doped NiAl . The Dy dopant prevented the oxide scale from rumpling and the formation of cavities beneath the oxide scale. Due to this, the oxide scale adhesion was significantly improved. For Dy -doped NiAl , the scale failure mostly occurred surrounding the oxide protrusions where were rich in Dy .

Scale Deformation and Failure in Hot Rolling: Understanding and Simulation

2011 ◽  
Vol 696 ◽  
pp. 144-149 ◽  
Author(s):  
Michal Krzyzanowski
Keyword(s):  
Oxide Scale ◽  
Hot Rolling ◽  
Predictive Accuracy ◽  
Element Analysis ◽  
Deformation And Failure ◽  
Chemical Content ◽  
Scale Properties ◽  
Physical Phenomena ◽  
Scale Failure

This work reviews recent advances in research on oxide scale behaviour in hot rolling processes. Presenting novel approaches, the paper emphasizes the crucial role of reproducible experiments to elucidate the scale properties coupled with numerical analysis to develop quantitative models with predictive accuracy. Oxide scale failure is predicted taking into consideration the main physical phenomena. The most critical for scale deformation and failure parameters are measured during testing and depend on the morphology, scale growth temperature. They are also very sensitive to the chemical content of the underlying metal. The work integrates the combined finite/discrete element analysis with a range of experiments each provide partial insight into oxide fracture, friction, heat transfer, descaling and pick-up, mechanical intermixing taking place near the stock surface among others.

scholarly journals Discontinuities in Oxidation Kinetics: A New Model and its Application to Cr–Si-Base Alloys

2021 ◽  
Author(s):  
Anke S. Ulrich ◽  
Uwe Glatzel ◽  
Mathias C. Galetz
Keyword(s):  
Oxide Scale ◽  
Oxidation Kinetics ◽  
Parabolic Rate Constant ◽  
Mass Gain ◽  
Linear Mass ◽  
Isothermal Exposure ◽  
Growth Stresses ◽  
Scale Failure ◽  
Insight Into ◽  
Rapid Mass

AbstractSome alloys such as many Cr-based systems show mass gain discontinuities during thermogravimetric measurements which strongly affect the oxidation kinetics. The behaviour cannot be described by the current models available in the literature. Thus, a novel $$k_\mathrm{para}$$ k para –$$k_\mathrm{lin}$$ k lin -P-model was developed to describe oxidation kinetics during the isothermal exposure of materials which show such behaviour. Beside the parabolic rate constant $$k_\mathrm{para}$$ k para and the linear mass loss constant $$k_\mathrm{lin}$$ k lin , the P-value and $$f_P$$ f P are introduced to take into account spontaneous rapid mass gains due to local oxide scale failure. The parameter P serves as a measure for the mass gain due to discontinuous events and $$f_P$$ f P is the frequency of such events. The both parameters can be related to oxide scale detachment and growth stresses. The application of the model is demonstrated for the oxidation of Cr–Si-based alloys in synthetic air at $$1200^{\circ }\hbox {C}$$ 1200 ∘ C for 100 h. For these alloys, the origin of the mass gain discontinuities is discussed and the meaning of P and $$f_P$$ f P is explained in more detail. Using this newly developed model, an insight into growth and nitridation resistance of oxide scales as well as scale adhesion is gained.

scholarly journals Soft Sensor for Oxide Scales on the Steam Side of Superheater Tubes under Uneven Circumferential Load

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
Qing Wei Li ◽  
Gui Huan Yao
Keyword(s):  
Oxide Scale ◽  
Soft Sensor ◽  
Support Vector ◽  
Oxide Scales ◽  
The Finite Element Method ◽  
Scale Thickness ◽  
Stress Sensors ◽  
Volume Method ◽  
First Time ◽  
Scale Failure

A soft sensor for oxide scales on the steam side of superheater tubes of utility boiler under uneven circumferential loading is proposed for the first time. First finite volume method is employed to simulate oxide scales growth temperature on the steam side of superheater tube. Then appropriate time and spatial intervals are selected to calculate oxide scales thickness along the circumferential direction. On the basis of the oxide scale thickness, the stress of oxide scales is calculated by the finite element method. At last, the oxide scale thickness and stress sensors are established on support vector machine (SMV) optimized by particle swarm optimization (PSO) with time and circumferential angles as inputs and oxide scale thickness and stress as outputs. Temperature and stress calculation methods are validated by the operation data and experimental data, respectively. The soft sensor is applied to the superheater tubes of some power plant. Results show that the soft sensor can give enough accurate results for oxide scale thickness and stress in reasonable time. The forecasting model provides a convenient way for the research of the oxide scale failure.

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