scholarly journals Atomic Simulations for Packing Changes of Nano-Sized Cu Clusters Embedded in the Febulk on Heating

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 934
Author(s):  
Peng Yu ◽  
Lin Zhang ◽  
Linxiu Du
Keyword(s):  
Structural Changes ◽  
Lattice Structure ◽  
Mean Square Displacement ◽  
Distribution Functions ◽  
Continuous Heating ◽  
Pressure Vessel Steel ◽  
Single Strain ◽  
Vessel Steel ◽  
Embedded Atom ◽  
Bcc Lattice

Understanding of the defect evolution mechanism under irradiation is very important for the research of pressure vessel steel embrittlement. In this paper, the embedded atom method (EAM) based canonical ensemble molecular dynamics (MD) method was used to study the evolution of the stacking structure of different nano-sized Cun (n = 13, 43 and 87) clusters in an Febulk embedded with BCC lattice structure during continuous heating. The mean square displacement, pair distribution functions and atomic structures of Cu atom clusters at the nanometer scale were calculated at different temperatures. The structural changes present apparent differences, for the Febulks contain nano-sized Cu clusters with different atom numbers during heating. For the Febulk–Cu13 system, since the ability to accommodate the atomic Cu in the Fe substrate is lesser, a small number of Cu atoms in BCC lattice positions cannot influence the whole structure of the Fe-Cu system. For the Febulk–Cu43 system, with an increase in temperature, a Cu atomic pile structural change happened, and the strain areas decreased significantly in the Febulk, but a single strain area grew large. For the Febulk–Cu87 system, when the Cu atoms are constrained by the Fe atoms in bulk, only a few of the Cu atoms adjust their positions. With the increase in temperature, strain in the Fe eased.

scholarly journals Inspection of Reactor Steel Degradation by Magnetic Adaptive Testing

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 963
Author(s):  
Gábor Vértesy ◽  
Antal Gasparics ◽  
Ildikó Szenthe ◽  
Ferenc Gillemot ◽  
Inge Uytdenhouwen
Keyword(s):  
Structural Changes ◽  
Magnetic Measurements ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Charpy Impact ◽  
Adaptive Testing ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Type Definition ◽  
Magnetic Adaptive Testing

Degradation of nuclear pressure vessel steel materials, 15Kh2NMFA type and A508 Cl2 type (definition is given in the text) were investigated by a novel magnetic nondestructive testing method, so-called Magnetic Adaptive Testing (MAT), which is based on systematic measurement and evaluation of minor magnetic hysteresis loops. The measured samples were thermally treated by a special step cooling procedure, which generated structural changes in the material. It was found that this type of degradation can be easily followed by magnetic measurements. Charpy impact test were also performed and the results were compared with the magnetic parameters. In case of 15Kh2NMFA steel, a good, reliable and closely linear correlation was found between magnetic descriptors and transition temperature.

Simulating Structural Transformation of a Cu1553 Nanoparticle on Heating at Atomic Scale

2015 ◽  
Vol 817 ◽  
pp. 736-739
Author(s):  
Jing Zhang ◽  
Peng Yu
Keyword(s):  
Structural Transformation ◽  
Structural Changes ◽  
Distribution Functions ◽  
Atomic Scale ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Different Temperatures ◽  
Dynamics Simulations ◽  
Pair Distribution Functions ◽  
Pair Analysis

By means of molecular dynamics simulations within the framework of embedded atom method, we observe the structural transformation of a Cu nanoparticle containing 1553 atoms at atomic scale on a heating series from 350K to 1200K at an increment of 50K. With increasing the temperature, the structural changes result in apparent increases in internal energy. Pair distribution functions (PDFs) and pair analysis (PA) technique as well as the atom packing at different temperatures are used to identify the local structural patterns during the melting of this particle.

Molecular Dynamics Investigation of Relaxation and Local Structure Changes in a Quenched Molten TiAl Alloy Film

2010 ◽  
Vol 650 ◽  
pp. 324-329
Author(s):  
Lin Zhang ◽  
Qin Na Fan ◽  
Cai Bei Zhang ◽  
Shao Qing Wang
Keyword(s):  
Molecular Dynamics ◽  
Local Structure ◽  
Tial Alloy ◽  
Mean Square Displacement ◽  
Alloy Film ◽  
Distribution Functions ◽  
Relaxation Processes ◽  
Embedded Atom ◽  
Structure Changes ◽  
Dynamics Simulations

Relaxation and local structure changes of a molten TiAl alloy film during quenching have been investigated by molecular dynamics simulations within the framework of embedded atom method (EAM). The details of atom motions are analyzed using mean square displacement (MSD). Accompanying with massive atom rearrangement at a certain quenched temperature and time, local structural patterns are identified by decomposing peaks of pair distribution functions (PDFs) according to the pair analysis(PA) technique. The relaxation factor clearly reveals two relaxation processes involving in slow relaxation and fast relaxation of the quenched liquid TiAl film. Concerning the studied film, the obtained results reveal how quenched temperatures affect local structure changes.

Dislocation structures in 16MND5 pressure vessel steel strained in uniaxial tension at −196°C

2005 ◽  
Vol 96 (8) ◽  
pp. 909-912
Author(s):  
Karel Obrtlík ◽  
Christian Robertson ◽  
Bernard Marini
Keyword(s):  
Uniaxial Tension ◽  
Pressure Vessel ◽  
Pressure Vessel Steel ◽  
Vessel Steel

scholarly journals Micromagnetic Characterization of Operation-Induced Damage in Charpy Specimens of RPV Steels

2021 ◽  
Vol 11 (7) ◽  
pp. 2917
Author(s):  
Madalina Rabung ◽  
Melanie Kopp ◽  
Antal Gasparics ◽  
Gábor Vértesy ◽  
Ildikó Szenthe ◽  
...  
Keyword(s):  
Neutron Irradiation ◽  
Pressure Vessel ◽  
Operating Conditions ◽  
Magnetic Characteristics ◽  
Pressure Vessel Steel ◽  
Training Procedure ◽  
Vessel Steel ◽  
Before And After ◽  
The Individual ◽  
Magnetic Adaptive Testing

The embrittlement of two types of nuclear pressure vessel steel, 15Kh2NMFA and A508 Cl.2, was studied using two different methods of magnetic nondestructive testing: micromagnetic multiparameter microstructure and stress analysis (3MA-X8) and magnetic adaptive testing (MAT). The microstructure and mechanical properties of reactor pressure vessel (RPV) materials are modified due to neutron irradiation; this material degradation can be characterized using magnetic methods. For the first time, the progressive change in material properties due to neutron irradiation was investigated on the same specimens, before and after neutron irradiation. A correlation was found between magnetic characteristics and neutron-irradiation-induced damage, regardless of the type of material or the applied measurement technique. The results of the individual micromagnetic measurements proved their suitability for characterizing the degradation of RPV steel caused by simulated operating conditions. A calibration/training procedure was applied on the merged outcome of both testing methods, producing excellent results in predicting transition temperature, yield strength, and mechanical hardness for both materials.

Multiaxial Fatigue of 16MnR Steel

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Zengliang Gao ◽  
Tianwen Zhao ◽  
Xiaogui Wang ◽  
Yanyao Jiang
Keyword(s):  
Pure Shear ◽  
Ambient Air ◽  
Shear Loading ◽  
Multiaxial Fatigue ◽  
Experimental Results ◽  
Pressure Vessel Steel ◽  
Critical Plane ◽  
Cracking Behavior ◽  
Vessel Steel ◽  
Axial Torsion

Uniaxial, torsion, and axial-torsion fatigue experiments were conducted on a pressure vessel steel, 16MnR, in ambient air. The uniaxial experiments were conducted using solid cylindrical specimens. Axial-torsion experiments employed thin-walled tubular specimens subjected to proportional and nonproportional loading. The true fracture stress and strain were obtained by testing solid shafts under monotonic torsion. Experimental results reveal that the material under investigation does not display significant nonproportional hardening. The material was found to display shear cracking under pure shear loading but tensile cracking under tension-compression loading. Two critical plane multiaxial fatigue criteria, namely, the Fatemi–Socie criterion and the Jiang criterion, were evaluated based on the experimental results. The Fatemi–Socie criterion combines the maximum shear strain amplitude with a consideration of the normal stress on the critical plane. The Jiang criterion makes use of the plastic strain energy on a material plane as the major contributor to the fatigue damage. Both criteria were found to correlate well with the experiments in terms of fatigue life. The predicted cracking directions by the criteria were less satisfactory when comparing with the experimentally observed cracking behavior under different loading conditions.

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