scholarly journals The Precipitated Particle Refinement in High-Cr ODS Steels by Microalloying Element Addition

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7767
Author(s):  
Yingying Li ◽  
Liye Zhang ◽  
Dijun Long ◽  
Liming Yu ◽  
Huijun Li
Keyword(s):  
Room Temperature ◽  
Grain Morphology ◽  
Oxide Dispersion Strengthened ◽  
Tensile Tests ◽  
High Thermal Stability ◽  
Oxide Dispersion ◽  
Ods Steel ◽  
Element Addition ◽  
Ods Steels ◽  
Particle Refinement

Two oxide-dispersion-strengthened (ODS) steels with different compositions (14Cr-ODS and 14Cr-Zr-ODS) were investigated to reveal the influences of microalloying element addition on the microstructure and to clarify the refining mechanism of precipitated particles. TEM and HRTEM results indicated that precipitated particles in the Zr-containing ODS steel had finer sizes and dispersed more homogeneously within the grains. It was found that rhombohedral Y4Zr3O12 particles with complex lattice structures were formed and could pin the migration of the grain boundaries during heat treatment due to their high thermal stability. In addition, the Zr-containing ODS steel exhibited a finer and more uniform grain morphology. Tensile tests showed that microalloying element addition could significantly improve the comprehensive mechanical properties of 14Cr ODS steels at room temperature.

scholarly journals Development of New 14 Cr ODS Steels by Using New Oxides Formers and B as an Inhibitor of the Grain Growth

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1344
Author(s):  
Alberto Meza ◽  
Eric Macía ◽  
Andrea García-Junceda ◽  
Luis Antonio Díaz ◽  
Paul Chekhonin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Growth ◽  
Electron Backscatter Diffraction ◽  
Oxide Dispersion Strengthened ◽  
Complex Oxide ◽  
Tensile Tests ◽  
Processing Route ◽  
Prealloyed Powder ◽  
Ods Steel ◽  
Ods Steels

In this work, new oxide dispersion strengthened (ODS) ferritic steels have been produced by powder metallurgy using an alternative processing route and characterized afterwards by comparing them with a base ODS steel with Y2O3 and Ti additions. Different alloying elements like boron (B), which is known as an inhibitor of grain growth obtained by pinning grain boundaries, and complex oxide compounds (Y-Ti-Zr-O) have been introduced to the 14Cr prealloyed powder by using mechanical alloying (MA) and were further consolidated by spark employing plasma sintering (SPS). Techniques such as x-ray diffraction (XRD), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) were used to study the obtained microstructures. Micro-tensile tests and microhardness measurements were carried out at room temperature to analyze the mechanical properties of the differently developed microstructures, which was considered to result in a better strength in the ODS steels containing the complex oxide Y-Ti-Zr-O. In addition, small punch (SP) tests were performed to evaluate the response of the material under high temperatures conditions, under which promising mechanical properties were attained by the materials containing Y-Ti-Zr-O (14Al-X-ODS and 14Al-X-ODS-B) in comparison with the other commercial steel, GETMAT. The differences in mechanical strength can be attributed to the precipitate’s density, nature, size, and to the density of dislocations in each ODS steel.

Creep Behavior and Microstructure of 8Cr Oxide Dispersion Strengthened Martensitic Steel

2010 ◽  
Vol 638-642 ◽  
pp. 2309-2314
Author(s):  
Kei Shinozuka ◽  
Hisao Esaka ◽  
M. Tamura ◽  
Hiroyasu Tanigawa
Keyword(s):  
Creep Deformation ◽  
Rolling Direction ◽  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion ◽  
Martensitic Steels ◽  
Creep Tests ◽  
Nuclear Fusion Reactor ◽  
Ods Steel ◽  
Temperature Oxide ◽  
Ods Steels

In international thermonuclear experimental reactor (ITER), reduced activation ferritic/martensitic steels will be used for plasma-facing materials. However, it is necessary to raise the temperature of operation in order to elevate efficiency of electric power generation by using the material which is more excellent in strength at elevated temperature. Oxide dispersion strengthened (ODS) steels are promising candidate for high temperature materials of a nuclear fusion reactor. There are many reports that ODS steels show very high creep strength, but there are few reports on creep deformation mechanism. In this work, creep deformation behavior of 8 wt% Cr ODS steel was investigated. This ODS steel had high density of fine dispersed Y2Ti2O7 particles and -ferrite grains elongated along the hot-rolling direction. The creep curve showed a low creep strain rate until specimen ruptured. Vickers hardness of the gauge part of specimens in interrupted creep tests decreased with increasing the loading time. However, that of the grip part did not change significantly. Accordingly, although dynamic recovery occurred in the ODS steel, it had not affected the creep deformation rate.

Oxidation of Oxide Dispersion Strengthened Steels: II. Kinetics and Mechanism

2013 ◽  
Vol 748 ◽  
pp. 106-111
Author(s):  
Jae Hoon Lee
Keyword(s):  
Grain Refinement ◽  
Oxidation Resistance ◽  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion ◽  
Protective Oxide ◽  
Alumina Layer ◽  
Ods Steel ◽  
Time Period ◽  
Oxide Particles ◽  
Ods Steels

The oxidation resistance of 18%Cr-oxide dispersion strengthened (ODS) ferritic steels with and without 5%Al has been investigated in air at 700900 °C for time period up to 540 h. The oxidation rate of ODS steels is significantly dependent on the oxidation time and temperature. Compared to Al-containing ODS steel, the finer grains of Al-free ODS steel are due to the formation of smaller coherent oxide particles which suppress the steel's grain growth. The grain refinement of ODS steels is expected to allow rapid segregation of Cr or Al to the steel surface, so that the continuous Fe-Cr spinel or alumina layer is formed quickly in comparison to the alloys without oxide particles dispersion. Therefore, the excellent oxidation resistance of ODS steels is owing to the formation of continuous, protective oxide layers which correlate with oxide nanoparticles and grain refinement.

Phenomena Leading to a Modification of the Nano-Sized Structure during Resistance Upset Welding of ODS Steel Cladding

2012 ◽  
Vol 706-709 ◽  
pp. 977-982 ◽  
Author(s):  
Fabien Corpace ◽  
A. Monnier ◽  
A. Poulon Quintin ◽  
J P. Manaud
Keyword(s):  
Mechanical Properties ◽  
Welding Process ◽  
Oxide Dispersion Strengthened ◽  
Fusion Welding ◽  
Oxide Dispersion ◽  
Fuel Cladding ◽  
Ods Steel ◽  
The Matrix ◽  
Ods Steels ◽  
Two Stages

ODS steels (Oxide Dispersion Strengthened) are candidate materials for fuel cladding in Sodium Fast Reactors (SFR). These materials have good mechanical properties at high temperature due to a dispersion of nanometer-sized oxides into the matrix. Previous studies have shown that melting can induce a decrease of the mechanical properties at high temperatures due to modifications of the nanometer-sized oxide dispersion. Therefore the fusion welding techniques are not recommended and the solid state boundings has to be evaluated. This study is focused on resistance upset welding. Welding experiments and numerical simulations are coupled. The numerical simulation is developed in order to have a better understanding of the thermal and the mechanical phenomena occurring during the welding process. The simulation shows that the welding steps can be divided in two stages. First, the temperature of the contact between pieces increases. Second, the heat generation is mainly located in the cladding leading to the collapse and forging the pieces. The microstructural observations confirm that the major deformation is located in the cladding. Oxide dispersion modification and dynamical recrystallisation has been found for welds achieved with a non optimized process parameter set. The deformation and the temperature seem to be of prime importance in the modification of the oxide dispersion.

Oxidation of Oxide Dispersion Strengthened Steels: I. Influence of Alloy Composition

2013 ◽  
Vol 748 ◽  
pp. 86-90 ◽  
Author(s):  
Jae Hoon Lee
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Alloy Composition ◽  
Critical Role ◽  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion ◽  
Temperature Oxidation ◽  
Ods Steel ◽  
Time Period ◽  
Ods Steels

Oxidation tests of 18%Cr-oxide dispersion strengthened (ODS) steels with and without 5%Al were carried out in air at 700900 °C for time period up to 540 h. No minor alloying elements affect the oxidation behavior and the Al concentration between these ODS steels is a main difference. Cr2O3and (Fe,Cr)3O4spinel oxides exist on the surface of 18Cr-ODS steel; however, the surface oxide of 18Cr5Al-ODS steel is comprised of only Al2O3. Oxidation resistance of the ODS steels exposed at 700 °C is much better than Incoloy800 of which the Cr content is larger and their oxidation behavior doesnt follow the aluminum content. These results suggest that oxide particles dispersion and grain refinement play a more critical role than alloy composition in the high-temperature oxidation resistance.

Mechanical and Microstructural Properties of Al-Added ODS Ferritic Steel

2012 ◽  
Vol 567 ◽  
pp. 49-53 ◽  
Author(s):  
Jae Hoon Lee
Keyword(s):  
Hot Extrusion ◽  
Oxide Dispersion Strengthened ◽  
Tensile Tests ◽  
Ods Steel ◽  
Dispersed Particles ◽  
Oxide Particles ◽  
Ods Steels ◽  
Ductile To Brittle Transition ◽  
The Difference ◽  
Mechanical And Microstructural Properties

18%Cr-oxide dispersion strengthened (ODS) ferritic steels with and without 5%Al have been produced by mechanical alloying and hot-extrusion. The microstructure of the ODS steels has been characterized by means of electron microscopy (SEM, TEM), showing that in the Al-added ODS steel, the semi-coherent and coherent oxide particles are about 75% and 10%, respectively. It was found that the coherency of oxide particles depends on the size of dispersed particles. Tensile tests performed between room temperature and 973 K denote that the ultimate tensile strength of Al-free ODS steel is higher than that of Al-added one. The ductility values of both materials are sufficiently high. Impact tests reveal that the ductile-to-brittle transition temperature of Al-free ODS steel are higher than that of Al-added ODS steel; however, the upper shelf energy of 18%Cr-ODS steel is substantially smaller in comparison to the Al-added one. It is considered that the difference in mechanical properties between Al-free and Al-added ODS steels is caused by the smaller, stable titania + yttria complex oxides dispersed in the Al-free ODS steel.

scholarly journals Joining of Oxide Dispersion-Strengthened Steel Using Spark Plasma Sintering

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1040
Author(s):  
Foad Naimi ◽  
Jean-Claude Niepce ◽  
Mostapha Ariane ◽  
Cyril Cayron ◽  
José Calapez ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Oxide Dispersion Strengthened ◽  
Tensile Tests ◽  
Control Surface ◽  
Oxide Dispersion ◽  
Simultaneous Application ◽  
Ods Steel ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Welding Processes

Difficulties with joining oxide dispersion-strengthened (ODS) steels using classical welding processes have led to the development of alternative joining techniques such as spark plasma sintering (SPS). SPS, which is classically employed for performing sintering, may also be used to join relatively large components due to the simultaneous application of electrical pulsed current and uniaxial charge. SPS technology was tested by joining two ODS steel disks. The preliminary tests showed that it is necessary to control surface roughness before joining. Furthermore, the use of ground and lapped surfaces seemed to improve the quality of the interface. Tensile tests on two ODS cylinders joined using SPS were performed at 750 °C without any additives. Failure occurred away from the interface with a total elongation close to 50% and an ultimate stress of 110 MPa.

scholarly journals Effect of Small Variations in Zr Content on the Microstructure and Properties of Ferritic ODS Steels Consolidated by SPS

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 348 ◽  
Author(s):  
Andrea García-Junceda ◽  
Eric Macía ◽  
Dariusz Garbiec ◽  
Marta Serrano ◽  
José M. Torralba ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion ◽  
Heating Rates ◽  
Ultrafine Grains ◽  
Ods Steel ◽  
Plasma Sintering ◽  
Final Microstructure ◽  
Spark Plasma ◽  
Ods Steels

Two different zirconium contents (0.45 and 0.60 wt.%) have been incorporated into a Fe-14Cr-5Al-3W-0.4Ti-0.25Y2O3 oxide dispersion-strengthened (ODS) steel in order to evaluate their effect on the final microstructure and mechanical properties. The powders with the targeted compositions were obtained by mechanical alloying (MA), and subsequently processed by spark plasma sintering (SPS) at two different heating rates: 100 and 400 °C·min−1. Non-textured bimodal microstructures composed of micrometric and ultrafine grains were obtained. The increase in Zr content led to a higher percentage of Zr nano-oxides and larger regions of ultrafine grains. These ultrafine grains also seem to be promoted by higher heating rates. The effective pinning of the dislocations by the Zr dispersoids, and the refining of the microstructure, have significantly increased the strength exhibited by the ODS steels during the small punch tests, even at high temperatures (500 °C).

scholarly journals Microstructure and Mechanical Properties of 14Cr-ODS Steels with Zr Addition

2019 ◽  
Vol 38 (2019) ◽  
pp. 404-410 ◽  
Author(s):  
Weijuan Li ◽  
Haijian Xu ◽  
Xiaochun Sha ◽  
Jingsong Meng ◽  
Zhaodong Wang
Keyword(s):  
Mechanical Properties ◽  
Hot Isostatic Pressing ◽  
Oxide Dispersion Strengthened ◽  
Nominal Composition ◽  
Ods Steel ◽  
Zr Addition ◽  
Microstructure And Mechanical Properties ◽  
The Matrix ◽  
Ods Steels ◽  
The Impact

AbstractIn this study, oxide dispersion strengthened (ODS) ferritic steels with nominal composition of Fe–14Cr–2W–0.35Y2O3 (14Cr non Zr-ODS) and Fe–14Cr–2W–0.3Zr–0.35Y2O3 (14Cr–Zr-ODS) were fabricated by mechanical alloying (MA) and hot isostatic pressing (HIP) technique to explore the impact of Zr addition on the microstructure and mechanical properties of 14Cr-ODS steels. Microstructure characterization revealed that Zr addition led to the formation of finer oxides, which was identified as Y4Zr3O12, with denser dispersion in the matrix. The ultimate tensile strength (UTS) of the non Zr-ODS steel is about 1201 MPa, but UTS of the Zr-ODS steel increases to1372 MPa, indicating the enhancement of mechanical properties by Zr addition.

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