Fracture behaviour of the 14Cr ODS steel exposed to helium and liquid lead

2017 ◽  
Vol 490 ◽  
pp. 143-154 ◽  
Author(s):  
Anna Hojna ◽  
Fosca Di Gabriele ◽  
Hynek Hadraba ◽  
Roman Husak ◽  
Ivo Kubena ◽  
...  
Keyword(s):  
Fracture Behaviour ◽  
Liquid Lead ◽  
Ods Steel

scholarly journals Mechanical properties and fracture behaviour of ODS steel friction stir welds at variable temperatures

2017 ◽  
Vol 693 ◽  
pp. 84-92 ◽  
Author(s):  
H. Dawson ◽  
M. Serrano ◽  
R. Hernandez ◽  
S. Cater ◽  
E. Jimenez-Melero
Keyword(s):  
Mechanical Properties ◽  
Fracture Behaviour ◽  
Friction Stir ◽  
Ods Steel

scholarly journals Why Do Secondary Cracks Preferentially Form in Hot-Rolled ODS Steels in Comparison with Hot-Extruded ODS Steels?

Crystals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 306 ◽  
Author(s):  
Aniruddh Das ◽  
Hans-Werner Viehrig ◽  
Eberhard Altstadt ◽  
Frank Bergner ◽  
Jan Hoffmann
Keyword(s):  
Electron Backscatter Diffraction ◽  
Fracture Behaviour ◽  
Grain Morphology ◽  
Predominant Role ◽  
Ods Steel ◽  
Secondary Cracks ◽  
Toughness Testing ◽  
Ods Steels ◽  
Hot Rolled ◽  
Backscatter Diffraction

Secondary cracks are known to absorb energy, retard primary crack propagation and initiate at lower loads than primary cracks. They are observed more often in hot-rolled than in hot-extruded ODS steels. In this work, the microstructural factors responsible for this observation are investigated. Better understanding of these factors can lead to tailoring of improved ODS steels. Fracture toughness testing of two batches of 13Cr ODS steel, one hot-rolled and the other hot-extruded, was carried out. The fracture behaviour of secondary cracks was investigated using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). Crystallographic texture and grain morphology play a predominant role in preventing secondary cracks in hot-extruded ODS steels. At lower temperatures, secondary cracks occur predominantly via transgranular cleavage. The fracture mode changes to ductile and intergranular at higher temperatures.

Non-stationary process characteristics of the gas outflow into a liquid

2019 ◽  
Vol 14 (2) ◽  
pp. 82-88
Author(s):  
M.V. Alekseev ◽  
I.S. Vozhakov ◽  
S.I. Lezhnin
Keyword(s):  
Numerical Simulation ◽  
Liquid Column ◽  
Gas Content ◽  
Liquid Lead ◽  
Gas Flows ◽  
Asymptotic Model ◽  
Process Characteristics ◽  
Significant Difference ◽  
Order Of Magnitude ◽  
Volume Method

A numerical simulation of the process of the outflow of gas under pressure into a closed container partially filled with liquid was carried out. For comparative theoretical analysis, an asymptotic model was used with assumptions about the adiabaticity of the gas outflow process and the ideality of the liquid during the oscillatory one-dimensional motion of the liquid column. In this case, the motion of the liquid column and the evolution of pressure in the gas are determined by the equation of dynamics and the balance of enthalpy. Numerical simulation was performed in the OpenFOAM package using the fluid volume method (VOF method) and the standard k-e turbulence model. The evolution of the fields of volumetric gas content, velocity, and pressure during the flow of gas from the high-pressure chamber into a closed channel filled with liquid in the presence of a ”gas blanket“ at the upper end of the channel is obtained. It was shown that the dynamics of pulsations in the gas cavity that occurs when the gas flows into the closed region substantially depends on the physical properties of the liquid in the volume, especially the density. Numerical modeling showed that the injection of gas into water occurs in the form of a jet outflow of gas, and for the outflow into liquid lead, a gas slug is formed at the bottom of the channel. Satisfactory agreement was obtained between the numerical calculation and the calculation according to the asymptotic model for pressure pulsations in a gas projectile in liquid lead. For water, the results of calculations using the asymptotic model give a significant difference from the results of numerical calculations. In all cases, the velocity of the medium obtained by numerical simulation and when using the asymptotic model differ by an order of magnitude or more.

scholarly journals Atomic structure and chemistry of complex oxide dispersoids in ferritic ODS steel clad tubes

2021 ◽  
Vol 27 (S1) ◽  
pp. 3306-3307
Author(s):  
Pradyumna Parida ◽  
Shyam Kanta Sinha ◽  
Arup Dasgupta
Keyword(s):  
Atomic Structure ◽  
Complex Oxide ◽  
Ods Steel

scholarly journals Microstructure, Grain Growth and Hardness of Nanostructured Ferritic ODS Steel Powder during Annealing

2021 ◽  
Author(s):  
Krzysztof Nowik ◽  
Zbigniew Oksiuta
Keyword(s):  
Dislocation Density ◽  
Size Distribution ◽  
Hot Isostatic Pressing ◽  
Domain Size ◽  
Oxide Dispersion Strengthened ◽  
Alloy Formation ◽  
Nanocrystalline State ◽  
Ferritic Alloy ◽  
Ods Steel ◽  
Double Phase

AbstractNanocrystalline oxide-dispersion strengthened ferritic alloy formation and its annealing behavior were examined through modern X-ray diffraction pattern analysis and supplemented by microhardness and microscopic measurements. The basic microstructure features, with particular emphasis on evolution of domain size distribution and defect content during mechanical and thermal treatment, were quantified via the whole powder pattern modeling approach. The microstructure of the powdered alloy, formed during mechanical alloying, evolved toward nanocrystalline state consisting of narrow dispersion of very fine crystallites with substantial dislocation density, which exhibited relatively high stability against elevated temperature. It was shown that crystallite size is seriously sustained by the grain-boundary strain, therefore coarsening of grains begins only after the density of dislocations drops below certain level. Obtaining correct results for the annealing-related data at specific temperature range required the incorporation of the “double-phase” model, indicating possible bimodal domain size distribution. The dislocation density and grain size were found not to be remarkably affected after consolidation by hot isostatic pressing.

scholarly journals Mesoscale Modelling of Concretes Subjected to Triaxial Loadings: Mechanical Properties and Fracture Behaviour

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1099
Author(s):  
Qingqing Chen ◽  
Yuhang Zhang ◽  
Tingting Zhao ◽  
Zhiyong Wang ◽  
Zhihua Wang
Keyword(s):  
Mechanical Properties ◽  
Tensile Stress ◽  
Failure Criterion ◽  
Mesoscale Model ◽  
Fracture Behaviour ◽  
Descent Method ◽  
Triaxial Stress ◽  
Gradient Descent Method ◽  
Stress States ◽  
Shear Failures

The mechanical properties and fracture behaviour of concretes under different triaxial stress states were investigated based on a 3D mesoscale model. The quasistatic triaxial loadings, namely, compression–compression–compression (C–C–C), compression–tension–tension (C–T–T) and compression–compression–tension (C–C–T), were simulated using an implicit solver. The mesoscopic modelling with good robustness gave reliable and detailed damage evolution processes under different triaxial stress states. The lateral tensile stress significantly influenced the multiaxial mechanical behaviour of the concretes, accelerating the concrete failure. With low lateral pressures or tensile stress, axial cleavage was the main failure mode of the specimens. Furthermore, the concretes presented shear failures under medium lateral pressures. The concretes experienced a transition from brittle fracture to plastic failure under high lateral pressures. The Ottosen parameters were modified by the gradient descent method and then the failure criterion of the concretes in the principal stress space was given. The failure criterion could describe the strength characteristics of concrete materials well by being fitted with experimental data under different triaxial stress states.

An interpretation on the thermodynamic properties of liquid Pb–Te alloys

2020 ◽  
Vol 39 (1) ◽  
pp. 297-303
Author(s):  
Toru Akasofu ◽  
Masanobu Kusakabe ◽  
Shigeru Tamaki
Keyword(s):  
Thermodynamic Properties ◽  
Electron Affinity ◽  
Ionization Energy ◽  
Narrow Band ◽  
Structural Information ◽  
Lead Telluride ◽  
Liquid Lead ◽  
Metallic State ◽  
Ternary Solution ◽  
Conduction Electrons

AbstractThe bonding character of liquid lead telluride \text{PbTe} is thermodynamically investigated in detail. Its possibility as an ionic melt composed of cation {\text{Pb}}^{2+} and anion {\text{Te}}^{2-} is not acceptable, by comparing the ionization energy of \text{Pb} atom, electron affinity of \text{Te} atom and the ionic bonding energy due to the cation {\text{Pb}}^{2+} and anion {\text{Te}}^{2-} with the help of structural information. Solid lead telluride PbTe as a narrow band gap semiconductor might yield easily the overlapping of the tail of valence band and that of conduction one. And on melting, it becomes to an ill-conditioned metallic state, which concept is supported by the electrical behaviors of liquid Pb–Te alloys observed by the present authors. As structural information tells us about the partial remain of some sorts of covalent-type mono-dipole and poly-dipole of the molecule \text{PbTe}, all systems are thermodynamically explained in terms of a mixture of these molecules and cations {\text{Pb}}^{4+} and {\text{Te}}^{2+} and a small amount of the conduction electrons are set free from these elements based on the ternary solution model.

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