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.

Characterization of oxide particles in ODS austenitic stainless steel after heavy ion irradiation up to high doses

2011 ◽  
Vol 1298 ◽  
Author(s):  
Hiroshi Oka ◽  
Yosuke Yamazaki ◽  
Hiroshi Kinoshita ◽  
Naoyuki Hashimoto ◽  
Somei Ohnuki ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Ion Irradiation ◽  
Hot Extrusion ◽  
Oxide Dispersion Strengthened ◽  
Complex Oxide ◽  
Heavy Ion ◽  
Oxide Particles ◽  
The Difference ◽  
High Doses

ABSTRACTOxide dispersion strengthened austenitic stainless steel (ODS316), which is based on advanced SUS316 steel, has been developed by mechanically alloying and hot extrusion. Hafnium and titanium were added to make a fine distribution of oxide particles. The stability of oxide particles dispersed in ODS316 under irradiation was evaluated after 250 keV Fe+ irradiation up to high doses at 500 °C. TEM observation and EDS analysis indicated that fine complex oxide particles with Y, Hf and Ti were mainly dispersed in the matrix. There are no significant changes in the distribution and the size of oxide particles after irradiation. It was also revealed that the constitution ratio of Ti in complex oxide appeared to be decreased after irradiation. This diffuse-out of Ti during irradiation could be explained by the difference in oxide formation energy among alloying elements.

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.

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.

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 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.

Temperature Dependent Mechanical Behavior of ODS Steels

2018 ◽  
Vol 941 ◽  
pp. 257-262
Author(s):  
Massimo de Sanctis ◽  
Alessandra Fava ◽  
Gianfranco Lovicu ◽  
Roberto Montanari ◽  
Maria Richetta ◽  
...  
Keyword(s):  
Grain Size ◽  
Mechanical Alloying ◽  
Mechanical Behavior ◽  
Hot Isostatic Pressing ◽  
Hot Extrusion ◽  
Oxide Dispersion Strengthened ◽  
Steel Powder ◽  
High Energy ◽  
Superior Mechanical Properties ◽  
Ods Steels

An oxide dispersion strengthened (ODS) ferritic steel with nanometric grain size has been produced by means of low-energy mechanical alloying (LEMA) of steel powder (Fe-14Cr-1W-0.4Ti) mixed with Y2O3 particles (0.3 wt%) and successive hot extrusion (HE). The material has equiaxed grains (mean size of 400 nm) and dislocation density of 4 x 1012 m-2, and exhibits superior mechanical properties with respect the unreinforced steel. The mechanical behavior has been compared with that of ODS steels prepared by means of the most common process, high-energy mechanical alloying (HEMA), consolidation through hot isostatic pressing (HIP) or hot extrusion (HE), annealing around 1100 °C for 1-2 hours, which produces a bimodal grain size distribution. The strengthening mechanisms have been examined and discussed to explain the different behavior.

Effect of Minor Alloying Element on Dispersing Nano-particles in ODS Steel

2006 ◽  
Vol 981 ◽  
Author(s):  
Y. Uchidi ◽  
S. Ohnuki ◽  
N. Hashimoto ◽  
T. Suda ◽  
T. Nagai ◽  
...  
Keyword(s):  
Hot Extrusion ◽  
Complex Oxides ◽  
Oxide Dispersion Strengthened ◽  
Ferrite Matrix ◽  
Nano Particles ◽  
High Temperature Strength ◽  
Ods Steel ◽  
Ma Process ◽  
Materials Used ◽  
Ti Addition

AbstractFrom the irradiation resistance and high-temperature strength, oxide dispersion strengthened (ODS) ferritic steels are candidate materials for advanced and fusion reactors. For the development of advanced steels the key issue is to homogenize nano-particles into matrix. Recent studies have indicated that Ti addition can homogenize Y-Ti complex particles into ferrite matrix, but the reason of the effect of additional elements has not been clarified. In this model study, we focus on the effect of additional elements, such as IV and V families and other oxide formers, which can control potentially the distribution of the oxide particles. The materials used in this study were based on Fe-9Cr-Y2O3 alloys which were mechanical alloyed (MA) from the powder of Fe, Cr and Y2O3, which was added systematically with the element of Ti, Zr, Ta, V, Nb, Hf, Al, Si and others. Usually ODS fabrication process is required for hot extrusion, but we annealed up to 1150 C for simplify the microstructure. To evaluate the distribution of ODS particles; we used TEM equipped with EDS after electro-polishing or FIB techniques. (1) In the case of Si or Al addition, oxides were disappeared after MA process, which means Y2O3 and other elements should be in solution at non-equilibrium condition. Two types of oxides of Y2O3 and Al2O3 or SiO2 developed after the annealing at 850 C, but only complex oxides were developed after the annealing at 1150 C. This result suggests that the oxide formation is independent process for Y and Si or Al. (2) In the case of Ti addition, oxides also were disappeared after MA process, but developed after annealing at 1150 C. This means that Ti can stabilize complex oxides of Y and Ti, and enhance the fine distribution of the oxides comparing with simple Fe-9Cr-Y2O3 alloy.

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.

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.

scholarly journals Effect of Oxygen Content on Microstructure and Tensile Properties of a 22Cr-5Al ODS Steel

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2241
Author(s):  
Yukun Zhang ◽  
Yingjie Yan ◽  
Yazhong Zhai ◽  
Wei Qin ◽  
Hongyan Che ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Grain Boundaries ◽  
Oxygen Content ◽  
Hot Isostatic Pressing ◽  
Oxide Dispersion Strengthened ◽  
Ods Steel ◽  
The Matrix ◽  
Ods Steels ◽  
Effect Of Oxygen ◽  
Content Of Oxygen

The high tensile strength and irradiation resistance of oxide dispersion strengthened (ODS) ferritic steels is attributed to the ultrafine and dispersed oxides within the matrix. The high content of oxygen and yttrium is critical for the formation of dense Y-rich oxides. However, only few studies have reported the effect of oxygen content on the microstructure and mechanical properties of ODS steels. Herein, we employed gas atomization reactive synthesis to prepare pre-alloy powders and then hot isostatic pressing (HIP) to consolidate two 22Cr-5Al ODS steels with different oxygen content. Our results showed Y-rich precipitates at and near grain boundaries of the as-HIPed alloys. Moreover, with the oxygen content increasing from 0.04 to 0.16 wt%, more precipitates precipitated in the as-HIPed alloy, and the ultimate tensile strength of the alloy was improved. However, increasing the oxygen content to 0.16 wt% led to formation of stripe and chain precipitates at and near grain boundaries, which caused a partial intergranular fracture of the as-HIPed alloy.

Sign in / Sign up

Export Citation Format

Share Document