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 Inhibition Effect of Ti on the Formation of Martensite Lath in 14Cr Oxide Dispersion Strengthened Steel

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 802 ◽  
Author(s):  
Qian Zhao ◽  
Zongqing Ma ◽  
Liming Yu ◽  
Huijun Li ◽  
Zumin Wang ◽  
...  
Keyword(s):  
Oxide Dispersion Strengthened ◽  
Friction Material ◽  
Martensite Lath ◽  
Oxide Dispersion ◽  
Secondary Phases ◽  
Ods Steel ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Cr Depletion ◽  
The Stability

Three model powders defined as MP powders (milled pre-alloyed powders), mixed powders (MX, 50 wt.% MP powders + 50 wt.% Oxide-Dispersion Strengthened powders) and Oxide Dispersion Strengthened (ODS) powders (alloyed pre-alloyed powders with the addition of Ti and Y2O3) are obtained under identical ball milling parameters. These powders are then consolidated under same sintering condition by spark plasma sintering (SPS) in order to investigate the formation mechanism of martensite lath in the MP steel and the effect of Ti on the stability of ferrite. The results indicate that the addition of Y2O3 and Ti powders can act as friction material during the mechanical alloying process, thus promoting the refinement effect. The formation of martensite lath in the MP steel is attributed to the local Cr depletion resulted from the large amounts of M23C6 precipitation. Ti possesses a strong affinity to C and long range diffusion ability, which efficiently prevents the martensite lath formation and local Cr depletion. Present study supports the conclusion that the lack of martensite in the MX and ODS steel is due to the addition of Ti. Secondary phases in these steels are identified and analyzed as well.

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.

Correlation between Milling Parameters, Structural and Mechanical Properties of Nanostructured Austenitic Y2O3 Strengthened Steels

2012 ◽  
Vol 729 ◽  
pp. 409-414 ◽  
Author(s):  
Péter Koncz ◽  
Ákos Horváth ◽  
Katalin Balázsi ◽  
Filiz Çinar Şahin ◽  
Gültekin Göller ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Oxide Dispersion Strengthened ◽  
Milling Process ◽  
Steel Matrix ◽  
X Ray Diffraction ◽  
Ods Steel ◽  
Plasma Sintering ◽  
High Efficient ◽  
Spark Plasma

In this paper, the correlation between structural and mechanical properties of nanostructured austenitic oxide dispersion strengthened (ODS) steel prepared by powder metallurgy were studied. High efficient milling process was applied to achive an optimal dispersion of ceramic oxide particles in the steel matrix. The austenitic powder with or without Y2O3 addition was milled by two different milling process (wet and dry). Spark plasma sintering as a fast and effective compaction method was used as sintering equipment. The morphology and structural properties of ODS were studied by X-ray diffraction and scanning electron microscopy. Mechanical properties, such as microhardness, bending strength and modulus of nanostructured ODS were also determined.

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.

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