Microstructure and Mechanical Property of 12Cr Oxide Dispersion Strengthened Steel

AbstractNanostructured oxide dispersion strengthened (ODS) steels with nominal compositions (wt%): Fe-12Cr-2W-0.3Ti-0.3Y2O3 were produced by mechanical alloying and hot isostatic pressing. The microstructure was characterized by means of electron microscopy (EBSD, TEM and HRTEM) and the hardness and the tensile properties at different temperatures were measured. The results showed that the ultimate tensile strength of the fabricated 12Cr-ODS steel reached nearly 1,100 MPa at room temperature and maintained around 340 MPa at 700°C. Nano-oxide particles with size ranging from several nm to 30 nm and the number density was 3.6 × 1020/m3 were observed by TEM. Following heat treatment, including normalizing at 1,100°C for 1 h and tempering at 750°C for 2 h, the average grain size was a little decreased. The number of nano-oxide particles increased and the number density was 8.9 × 1020/m3. Specimens showed much higher ductility and there was a slight increase of ultimate tensile strength and Vickers hardness at the same time.

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Effects of Consolidation Process on the Microstructure and Mechanical Properties of ODS Ferritic Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.747-748.507 ◽

2013 ◽

Vol 747-748 ◽

pp. 507-512 ◽

Cited By ~ 2

Author(s):

Tong Liu ◽

Hai Long Shen ◽

Tong Wen Zhang ◽

Mu Zhu ◽

Cheng Gong Qin

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Hot Isostatic Pressing ◽

Oxide Dispersion Strengthened ◽

Consolidation Process ◽

Ferritic Alloy ◽

Plasma Sintering ◽

The Matrix ◽

Spark Plasma ◽

Oxide Particles

The oxide-dispersion-strengthened (ODS) ferritic alloy powders (Fe-14Cr-3Al-2W-0.1Ti-0.35Y2O3) were prepared by mechanical alloying (MA) at a rotation speed of 720 rpm for 24 h. All the elements were mixed homogenously in the powder, and Cr and Al dissolved in α-Fe after MA. The bulk samples were produced by spark plasma sintering (SPS) at 950 and 50 MPa and by hot isostatic pressing (HIP) at 1150 and 130 MPa, respectively. The SPS sample showed a tensile strength of 730 MPa and a poor ductility due to the existence of pores in microsize. The HIP sample had a high tensile strength of 980 MPa, yield strength of 710 MPa and elongation of 10.3 %. The excellent mechanical properties of the HIP sample was due to the small grain size of the matrix of about 400 nm and the fine oxide particles of 5-40 nm.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.748.106 ◽

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.

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

Materials ◽

10.3390/ma14092241 ◽

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.

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Nano-oxide Particle Formation Mechanism and Stability in Oxide Dispersion Strengthened (ODS) Steel

Materia Japan ◽

10.2320/materia.59.183 ◽

2020 ◽

Vol 59 (4) ◽

pp. 183-190

Author(s):

Naoko Oono-Hori

Keyword(s):

Formation Mechanism ◽

Oxide Particle ◽

Oxide Dispersion Strengthened ◽

Particle Formation ◽

Oxide Dispersion ◽

Ods Steel ◽

Nano Oxide

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Microstructure and Mechanical Properties of 9Cr-ODS Ferritic/Martensitic Steels by Mechanically Alloyed and Spark Plasma Sintering

Materials Science Forum ◽

10.4028/www.scientific.net/msf.747-748.636 ◽

2013 ◽

Vol 747-748 ◽

pp. 636-640 ◽

Cited By ~ 1

Author(s):

Jian Yang ◽

Zhi Meng Guo ◽

Wei Wei Yang ◽

Ji Luo ◽

Cun Guang Chen

Keyword(s):

Tensile Strength ◽

Ultimate Tensile Strength ◽

Yield Strength ◽

Spark Plasma Sintering ◽

Water Solution ◽

Oxide Dispersion Strengthened ◽

Martensitic Steels ◽

Ods Steel ◽

Plasma Sintering ◽

Spark Plasma

9Cr-0.35wt.%Y2O3 oxide dispersion strengthened (ODS) ferritic/martensitic steels were prepared by mechanically alloying (MA) and spark plasma sintering (SPS). FE-SEM and TEM with X-ray energy spectrum (EDX) were employed to characterize the microstructural evolution and chemical composition before and after heat treatment. The tensile properties at room temperature were also investigated by electronic tensile test. The result shows that it is mainly of equiaxed ferrite microstructure by SPS with mean grain size of about 500nm. Dispersoids about 5-20nm which are enriched in Y, Ti and O uniformly distribute in the matrix. It exhibits a high relative density, ultimate tensile strength and yield strength of 99.5%, 1554MPa and 1430MPa, respectively. The microstructures are of slender lath martensitic after 10%NaCl water solution quenching, while after tempering at 750 which change into mainly equiaxed ferritic and a little residual ferrite. The ODS steel exhibits ultimate tensile strength, yield strength and total elongation of 1198MPa, 1006MPa and 12.8% after tempering, respectively.

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Microstructure Study of Pulsed Laser Beam Welded Oxide Dispersion-Strengthened (ODS) Eurofer Steel

Micromachines ◽

10.3390/mi12060629 ◽

2021 ◽

Vol 12 (6) ◽

pp. 629

Author(s):

Jia Fu ◽

Ian Richardson ◽

Marcel Hermans

Keyword(s):

Grain Size ◽

Laser Beam ◽

Fusion Zone ◽

Pulsed Laser ◽

Oxide Dispersion Strengthened ◽

Filler Material ◽

Oxide Dispersion ◽

Nano Oxide ◽

Oxide Particles ◽

Pulsed Laser Beam

Oxide dispersion-strengthened (ODS) Eurofer steel was laser welded using a short pulse duration and a designed pattern to minimise local heat accumulation. With a laser power of 2500 W and a duration of more than 3 ms, a full penetration can be obtained in a 1 mm thick plate. Material loss was observed in the fusion zone due to metal vaporisation, which can be fully compensated by the use of filler material. The solidified fusion zone consists of an elongated dual phase microstructure with a bimodal grain size distribution. Nano-oxide particles were found to be dispersed in the steel. Electron backscattered diffraction (EBSD) analysis shows that the microstructure of the heat-treated joint is recovered with substantially unaltered grain size and lower misorientations in different regions. The experimental results indicate that joints with fine grains and dispersed nano-oxide particles can be achieved via pulsed laser beam welding using filler material and post heat treatment.

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ODS EUROFER Steel Strengthened by Y-(Ce, Hf, La, Sc, and Zr) Complex Oxides

Metals ◽

10.3390/met9111148 ◽

2019 ◽

Vol 9 (11) ◽

pp. 1148 ◽

Cited By ~ 2

Author(s):

Roman Husák ◽

Hynek Hadraba ◽

Zdeněk Chlup ◽

Milan Heczko ◽

Tomáš Kruml ◽

...

Keyword(s):

Grain Size ◽

Yield Strength ◽

Complex Oxides ◽

Oxide Dispersion Strengthened ◽

Interparticle Spacing ◽

Oxide Dispersion ◽

Strengthening Effect ◽

Dispersion Strengthening ◽

Doping Element ◽

Average Grain Size

Oxide dispersion-strengthened (ODS) materials contain homogeneous dispersions of temperature-stable nano-oxides serving as obstacles for dislocations and further pinning of grain boundaries. The strategy for dispersion strengthening based on complex oxides (Y-Hf, -Zr, -Ce, -La) was developed in order to refine oxide dispersion to enhance the dispersion strengthening effect. In this work, the strengthening of EUROFER steel by complex oxides based on Y and elements of the IIIB group (lanthanum, scandium) and IVB group (cerium, hafnium, zirconium) was explored. Interparticle spacing as a dispersoid characteristic appeared to be an important factor in controlling the dispersion strengthening contribution to the yield strength of ODS EUROFER steels. The dispersoid size and average grain size of ODS EUROFER steel were altered in the ranges of 5–13 nm and 0.6–1.7 µm, respectively. Using this strategy, the yield strength of the prepared alloys varied between 550 MPa and 950 MPa depending on the doping element.

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Microstructure, Grain Growth and Hardness of Nanostructured Ferritic ODS Steel Powder during Annealing

Metallography Microstructure and Analysis ◽

10.1007/s13632-021-00746-6 ◽

2021 ◽

Author(s):

Krzysztof Nowik ◽

Zbigniew Oksiuta

Keyword(s):

Dislocation Density ◽

Size Distribution ◽

Hot Isostatic Pressing ◽

Domain Size ◽

Oxide Dispersion Strengthened ◽

Alloy Formation ◽

Nanocrystalline State ◽

Ferritic Alloy ◽

Ods Steel ◽

Double Phase

AbstractNanocrystalline oxide-dispersion strengthened ferritic alloy formation and its annealing behavior were examined through modern X-ray diffraction pattern analysis and supplemented by microhardness and microscopic measurements. The basic microstructure features, with particular emphasis on evolution of domain size distribution and defect content during mechanical and thermal treatment, were quantified via the whole powder pattern modeling approach. The microstructure of the powdered alloy, formed during mechanical alloying, evolved toward nanocrystalline state consisting of narrow dispersion of very fine crystallites with substantial dislocation density, which exhibited relatively high stability against elevated temperature. It was shown that crystallite size is seriously sustained by the grain-boundary strain, therefore coarsening of grains begins only after the density of dislocations drops below certain level. Obtaining correct results for the annealing-related data at specific temperature range required the incorporation of the “double-phase” model, indicating possible bimodal domain size distribution. The dislocation density and grain size were found not to be remarkably affected after consolidation by hot isostatic pressing.

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Vibratory weld conditioning during gas tungsten arc welding of al 5052 alloy on the mechanical and micro-structural behavior

World Journal of Engineering ◽

10.1108/wje-06-2020-0211 ◽

2020 ◽

Vol 17 (6) ◽

pp. 831-836

Author(s):

M. Vykunta Rao ◽

Srinivasa Rao P. ◽

B. Surendra Babu

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Tensile Strength ◽

Ultimate Tensile Strength ◽

Welded Joints ◽

Great Influence ◽

Welding Process ◽

Microstructural Characterization ◽

Content Type ◽

Average Grain Size

Purpose Vibratory weld conditioning parameters have a great influence on the improvement of mechanical properties of weld connections. The purpose of this paper is to understand the influence of vibratory weld conditioning on the mechanical and microstructural characterization of aluminum 5052 alloy weldments. An attempt is made to understand the effect of the vibratory tungsten inert gas (TIG) welding process parameters on the hardness, ultimate tensile strength and microstructure of Al 5052-H32 alloy weldments. Design/methodology/approach Aluminum 5052 H32 specimens are welded at different combinations of vibromotor voltage inputs and time of vibrations. Voltage input is varied from 50 to 230 V at an interval of 10 V. At each voltage input to the vibromotor, there are three levels of time of vibration, i.e. 80, 90 and 100 s. The vibratory TIG-welded specimens are tested for their mechanical and microstructural properties. Findings The results indicate that the mechanical properties of aluminum alloy weld connections improved by increasing voltage input up to 160 V. Also, it has been observed that by increasing vibromotor voltage input beyond 160 V, mechanical properties were reduced significantly. It is also found that vibration time has less influence on the mechanical properties of weld connections. Improvement in hardness and ultimate tensile strength of vibratory welded joints is 16 and 14%, respectively, when compared without vibration, i.e. normal weld conditions. Average grain size is measured as per ASTM E 112–96. Average grain size is in the case of 0, 120, 160 and 230 is 20.709, 17.99, 16.57 and 20.8086 µm, respectively. Originality/value Novel vibratory TIG welded joints are prepared. Mechanical and micro-structural properties are tested.

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