scholarly journals Localization of Plastic Deformation in the Copper and Stainless Steels Samples, Irradiated with Neutrons

2022 ◽  
Vol 2155 (1) ◽  
pp. 012009
Author(s):  
Mikhail Merezhko ◽  
Diana Merezhko
Keyword(s):  
Neutron Irradiation ◽  
Stainless Steels ◽  
Materials Science ◽  
Uniform Elongation ◽  
Reactor Core ◽  
Local Deformation ◽  
Austenitic Steels ◽  
Face Centered Cubic ◽  
Term Operation ◽  
Α Phase

Abstract The reduction of ductility of austenitic stainless steels as a result of long-term operation in the nuclear reactor core is an important problem of modern radiation materials science. Understanding the mechanisms of the effect of neutron irradiation on the mechanical properties of austenitic steels is impossible without research of localization processes occurring during the deformation. In this paper, it was found that the value of the true local deformation corresponding to the onset of neck formation in face-centered cubic structured metals decreases with an increase in the radiation dose, while the true stress remains almost constant. Additional hardening of AISI 304 steel due to the intensive formation of the martensitic α’-phase increases not only the stress at which a neck is formed in this alloy, but also the true local deformation. As a result, the uniform elongation increases and remains high after neutron irradiation to 0.05 dpa. The forehanded formation of the martensitic α’-phase in sufficient quantity before the necking onset can be considered as an additional deformation mechanism that will increase the ability of the material to deform uniformly.

TRIP Effect and Deformation Damaging of Metastable Austenitic Steels

2007 ◽  
Vol 539-543 ◽  
pp. 4903-4908 ◽  
Author(s):  
H. Oettel ◽  
M. Glavatskikh ◽  
U. Martin ◽  
A. Nikulin
Keyword(s):  
Crack Formation ◽  
Uniform Elongation ◽  
Shear Bands ◽  
Local Deformation ◽  
Austenitic Steels ◽  
Low Flow ◽  
Trip Effect ◽  
Fracture Path ◽  
Continuous Transformation ◽  
Additional Hardening

The TRIP – effect in metastable austenitic steels is caused by a moderate local martensitic transformation, connected with an extraordinary increase e.g. of the uniform elongation in tensile testing. In this case the martensite formation causes an additional hardening effect, preventing the local deformation as well as damaging during plastic deformation. The main conditions of a marked TRIP – effect is a low flow stress in the undeformed state, a high strengthening exponent, a continuous transformation up to about 20 % martensite and a high resistance against damaging (e.g. crack formation and propagation). The martensite transformation starts in glide or shear bands and their crossings also at temperatures clearly above the conventional Md – temperatures, reducing the stress local concentrations and so preventing damaging. Furthermore, high martensite contents can be detected along the fracture path, indicating the hindering of the crack propagation by the transformation. To demonstrate the influence of damaging on the TRIP – effect the deviations from the so-called Considere-criterion for uniform elongation can be used. Related to the deformation the damaging under TRIP – conditions is minimal.

Voids in Irradiated Tungsten and Molybdenum

1969 ◽  
Vol 27 ◽  
pp. 190-191
Author(s):  
Robert C. Rau ◽  
Robert L. Ladd
Keyword(s):  
Melting Point ◽  
Fast Neutron ◽  
Neutron Irradiation ◽  
Elevated Temperatures ◽  
Irradiation Temperature ◽  
The Body ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Cubic Metals ◽  
Face Centered

Recent studies have shown the presence of voids in several face-centered cubic metals after neutron irradiation at elevated temperatures. These voids were found when the irradiation temperature was above 0.3 Tm where Tm is the absolute melting point, and were ascribed to the agglomeration of lattice vacancies resulting from fast neutron generated displacement cascades. The present paper reports the existence of similar voids in the body-centered cubic metals tungsten and molybdenum.

scholarly journals Composition equivalents of stainless steels understood via gamma stabilizing efficiency

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shuqi Zhang ◽  
Qing Wang ◽  
Rui Yang ◽  
Chuang Dong
Keyword(s):  
Stainless Steel ◽  
Phase Boundary ◽  
Stainless Steels ◽  
Alloying Elements ◽  
Positive Sign ◽  
Equivalent Scheme ◽  
Α Phase ◽  
Phase Type ◽  
Boundary Lines

AbstractThe phase-type of a stainless steel is generally predicted by equivalent equations in terms of a major austenitic (γ) or ferritic (α) stabilizer Ni or Cr. The present paper attempts to understand the equivalent methods in stainless steels via the slopes of the phase boundary lines separating γ and γ + α phase zones. The prevailing equivalent coefficients are well interpreted using the slope ratios of the alloying elements divided by that of Ni or Cr, after analyzing over one hundred common stainless steels. Different from traditional composition equivalents which evaluate γ stabilizers and α stabilizers separately; the new equivalent scheme provides a unified phase stabilizing parameter for all alloying elements in stainless steels. This parameter is defined as γ stabilizing efficiency. Its negative or positive sign indicates γ stabilizer or α stabilizer, and its value represents the stabilizing efficiency.

Grain Refinement and Deformation Behavior of Ultrafine Grained Pd and Pd-Ag Alloys Produced by HPT

2008 ◽  
Vol 584-586 ◽  
pp. 182-187
Author(s):  
Lilia Kurmanaeva ◽  
Yulia Ivanisenko ◽  
J. Markmann ◽  
Ruslan Valiev ◽  
Hans Jorg Fecht
Keyword(s):  
Mechanical Properties ◽  
Deformation Behavior ◽  
Materials Science ◽  
High Pressure Torsion ◽  
Uniform Elongation ◽  
Grain Structure ◽  
Coarse Grained ◽  
Ultrafine Grain ◽  
Ultrafine Grained ◽  
Ultrafine Grain Structure

Investigations of mechanical properties of nanocrystalline (nc) materials are still in interest of materials science, because they offer wide application as structural materials thanks to their outstanding mechanical properties. NC materials demonstrate superior hardness and strength as compared with their coarse grained counterparts, but very often they possess a limited ductility or show low uniform elongation due to poor strain hardening ability. Here, we present the results of investigation of the microstructure and mechanical properties of nc Pd and Pd-x%Ag (x=20, 60) alloys. The initially coarse grained Pd-x% Ag samples were processed by high pressure torsion, which resulted in formation of homogenous ultrafine grain structure. The increase of Ag contents led to the decrease of the resulted grain size and change in deformation behavior, because of decreasing of stacking fault energy (SFE). The samples with larger Ag contents demonstrated the higher values of hardness, yield stress and ultimate stress. Remarkably the uniform elongation had also increased with increase of strength.

Thermal Ageing Embrittlement of Casting Duplex Stainless Steels for Nuclear Power Plant

2010 ◽  
Author(s):  
Yuhong Yao ◽  
Jianfeng Wei ◽  
Jiangnan Liu ◽  
Zhengpin Wang ◽  
Yu Wang
Keyword(s):  
Stainless Steels ◽  
Thermal Aging ◽  
Nuclear Power ◽  
Power Plants ◽  
Ageing Time ◽  
Thermal Ageing ◽  
Duplex Stainless Steels ◽  
Impact Properties ◽  
Α Phase ◽  
The Impact

Cast duplex stainless steels (CSS) used for PWR pipes are degraded due to thermal ageing embrittlement during long-term service at 288 °C to 327 °C. Z3CN20-09M Cast duplex Stainless Steels (CSS) made in France for domestic nuclear power plants were thermally aged at 400 °C for 100 h, 300 h, 1000 h, 3000 h and 10000 h. The tensile properties and the impact properties at different thermal aging duration were measured and the effects of the thermal aging time on the microscopic structures and substructures of Z3CN20-09M were respectively investigated by optical microscopy and transmission electron microscopy. The results showed that the tensile strengths of Z3CN20-09M CSS increased gradually with the increment of the thermal ageing time, whereas the impact properties decreased with the prolonging of the thermal ageing time. After long thermal ageing time the dislocation configurations were greatly changed in austenite, and there were precipitates along the austenite-ferrite interface. Moreover, the iron-rich α phase and the chromium-rich α phase precipitated in ferrite aged for 10000h by nucleation and growth rather than the spinodal decomposition. All of above revealed that Z3CN20-09M CSS became brittle during thermal ageing.

Effects of Neutron Irradiation on Tensile Properties of V-Ti-Cr-Si Type Alloys with Pre-Existing Helium

1998 ◽  
Vol 540 ◽  
Author(s):  
M. Satou ◽  
T. Chuto ◽  
H. Koide ◽  
A. Hasegawa ◽  
K. Abe
Keyword(s):  
Low Temperature ◽  
Ambient Temperature ◽  
Tensile Properties ◽  
Yield Stress ◽  
Neutron Irradiation ◽  
Uniform Elongation ◽  
Temperature Range ◽  
Temperature Irradiation ◽  
Helium Implantation ◽  
Lower Temperature

AbstractHelium effect on loss of uniform elongation after low-temperature neutron irradiation of the V-Ti-Cr-Si-Al-Y alloy was studied. Helium implantation to about 30 atomic ppm was carried out before neutron irradiation to 50 dpa at 406°C. The yield stress of the irradiated specimen with helium pre-implantation was slightly smaller than that of irradiated specimens without helium. The uniform elongation and the increase in yield stress of the irradiated specimens were not affected by helium pre-implantation at ambient temperature. It might be possible that the helium effect appears after lower temperature irradiation such as 300°C or lower, which corresponds to the temperature range where the loss of uniform elongation of the alloy is particularly pronounced.

Irradiation Hardening of Austenitic Stainless Steels: From Field Experience to Modeling

2004 ◽  
Author(s):  
C. Pokor ◽  
Y. Thebault ◽  
C. Pujol ◽  
J.-P. Massoud ◽  
D. Loisnard ◽  
...  
Keyword(s):  
Neutron Irradiation ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Pressurized Water Reactors ◽  
Iterative Approach ◽  
Pressurized Water ◽  
Irradiation Hardening ◽  
The Core ◽  
Water Reactors ◽  
Life Predictions

Materials for the core internals of Pressurized Water Reactors (austenitic stainless steels) are submitted to neutron irradiation. To understand the ageing mechanisms associated to irradiation and propose life predictions of the component, a multi step iterative approach consisting in particular in modeling the evolution of the hardening has been undertaken. Combination of characterization and modeling of simplified situations and field expertise is proposed.

scholarly journals Investigation of Electroplastic Effect on Four Grades of Duplex Stainless Steels

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1911 ◽  
Author(s):  
Claudio Gennari ◽  
Luca Pezzato ◽  
Enrico Simonetto ◽  
Renato Gobbo ◽  
Michele Forzan ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Stress ◽  
Stainless Steels ◽  
Uniform Elongation ◽  
Electrical Current ◽  
Total Elongation ◽  
Duplex Stainless Steels ◽  
Electroplastic Effect ◽  
Two Phases

Since the late 1950s, an effect of electrical current in addition to joule heating on the deformation of metals called the Electroplastic Effect (EPE) has been known. It is used nowadays in the so-called Electrically Assisted Forming (EAF) processes, but the understanding of the phenomenon is not very clear yet. It has been found that EPE increases the formability of high stacking fault energy (SFE) materials, while low SFE materials reach fracture prematurely. Since Duplex Stainless Steels (DSSs) possess a microstructure consisting of two phases with very different SFE (low SFE austenite and high SFE ferrite) and they are widely used in industry, we investigated EPE on those alloys. Tensile tests at 5 A/mm2, 10 A/mm2 and 15 A/mm2 current densities along with thermal counterparts were conducted on UNS S32101, UNS S32205, UNS S32304 and UNS S32750. The DSS grades were characterized by means of optical microscopy, X-ray diffraction and their mechanical properties (ultimate tensile strength, total elongation, uniform elongation and yield stress). An increase in uniform elongation for the electrical tests compared to the thermal counterparts as well as an increase in total elongation was found. No differences were observed on the yield stress and on the ultimate tensile strength. Un uneven distribution of the current because of the different resistivity and work hardening of the two phases has been hypothesized as the explanation for the positive effect of EPE.

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