Strength correlation with residual ferrite fraction in 9CrODS ferritic steel

Miyata, R.; Ukai, Shigeharu; Wu, Xiaochao; Oono, Naoko; Hayashi, Shigenari; Ohtsuka, Satoshi; Kaito, Takeji

doi:10.1016/j.jnucmat.2013.04.086

Cited by 11 publications

(4 citation statements)

References 14 publications

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“…It suggests that the strengthening mechanisms that make martensite much more resistant than ferrite at room temperature are not the same at 650°C. In different studies [12][13][14], the presence of residual ferrite was found. This phase did not undergo the austenitisation and TEM analysis showed that it contains a higher density and a finer diameter of nano-particles than martensite.…”

Section: Discussionmentioning

confidence: 97%

“…In fact, observations on the dualphase cylindrical sample using SEM with the backscattering electron detector in Figure 9 showed only large grains on the edge of the sample. It is known that low carbon content promotes growth of ferrite [13] and thus increases the quench critical rates, which determine the formation domain of the different microstructures. To support this hypothesis, micro-hardness measurements (load 100 g) were performed across the thickness of the tube.…”

Section: Discussionmentioning

confidence: 99%

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Investigation of the relationships between mechanical properties and microstructure in a Fe-9%Cr ODS steel

Hary

Guilbert

Wident

et al. 2016

EPJ Nuclear Sci. Technol.

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Abstract. Ferritic-martensitic Oxide Dispersion Strengthened (ODS) steels are potential materials for fuel pin cladding in Sodium Fast Reactor (SFR) and their optimisation is essential for future industrial applications. In this paper, a feasibility study concerning the generation of tensile specimens using a quenching dilatometer is presented. The ODS steel investigated contains 9%Cr and exhibits a phase transformation between ferrite and austenite around 870°C. The purpose was to generate different microstructures and to evaluate their tensile properties. Specimens were machined from a cladding tube and underwent controlled heat treatments inside the dilatometer. The microstructures were observed using Electron Backscatter Diffraction (EBSD) and tensile tests were performed at room temperature and at 650°C. Results show that a tempered martensitic structure is the optimum state for tensile loading at room temperature. At 650°C, the strengthening mechanisms that are involved differ and the microstructures exhibit more similar yield strengths. It also appeared that decarburisation during heat treatment in the dilatometer induces a decrease in the mechanical properties and heterogeneities in the dual-phase microstructure. This has been addressed by proposing a treatment with a much shorter time in the austenitic domain. Thereafter, the relaxation of macroscopic residual stresses inside the tube during the heat treatment was evaluated. They appear to decrease linearly with increasing temperature and the phase transformation has a limited effect on the relaxation.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Investigation of the relationships between mechanical properties and microstructure in a Fe-9%Cr ODS steel

Hary

Guilbert

Wident

et al. 2016

EPJ Nuclear Sci. Technol.

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“…The residual ferrite is characteristics of high density of oxide nanoparticles, exhibiting higher hardness than the tempered martensite. It can improve the creep strength of 9Cr ODS steels by combining the soft tempered martensite and hard residual ferrite [15]. A small amount of residual ferrite can induce easy deformation of the soft tempered martensite, while large volumes of residual ferrite tend to induce stress concentration and lead to cracks at the soft/hard interface [16,17].…”

Section: Introductionmentioning

confidence: 99%

Residual Ferrite Control of 9Cr ODS Steels by Tailoring Reverse Austenite Transformation

Zhou

Chen

Liu

et al. 2021

Acta Metall. Sin. (Engl. Lett.)

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By tailoring the reverse austenite transformation behavior of 9Cr oxide dispersion strengthened (ODS) ferritic/martensitic steels, the residual ferrite in ODS steels can be controlled. The reverse austenite transformation behavior of ODS steels is closely related to the initial microstructure conditions prior to austenite transformation. For the spark plasma sintered steels, both the amount and size of residual ferrite decrease with increasing heating rate. Nevertheless, high heating rate will increase the amount and size of residual ferrite in annealed ODS steels. As an isothermal treatment is performed at temperatures above Ac 1 , lower isothermal temperature has a more evident effect on the ferrite distribution in spark plasma sintered steels than that in annealed ones.

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“…For well-studied materials hardness values can be converted to yield strength and elastic modulus values using empirical data[44].Bulk mechanical property testing on Fe-Cr alloys have been conducted in the literature in both the as received[11,46,47,[55][56][57][58][59] and irradiated[60][61][62] conditions. In general, the response of an irradiated Fe-9%Cr alloy is to increase both the yield strength and ultimate tensile strength, while reducing ductility as shown in the figure above.As can be seen, some of the most prevalent conventional tests in the literature are hardness and tensile testing.…”

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confidence: 99%

In Situ TEM Micropillar Compression Testing in Irradiated Oxide Dispersion Strengthened Alloys

Yano¹

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To start, I would like to thank my advisor, Dr. Janelle Wharry, for her patience and endless support throughout this effort. Thank you especially to Dr. Claire Xiong for being willing to oversee my last year here at BSU and for the push to complete this thesis. I'd also like to acknowledge and thank my other committee members for their participation in this process. Much of this work was conducted at the MaCS at CAES. Jatu Burns and Allyssa Bateman-thanks for sharing your wisdom and knowledge of the FIB. Joanna Taylorthanks for accommodating my last-minute schedule changes. Dr. Yaqiao Wu-thank you for all your help on the TEM. Without your assistance loading my samples into the Picoindenter, I'm afraid many more samples would have been lost. Your expertise with the TEM was essential and saved me many grueling hours aligning the indenter tip. Matthew Swenson-thanks for all your help in this endeavor. I appreciate all the time you took to teach me the ropes, all the long drives to Idaho Falls, and all the latenights FIB-ing out samples. Your mentorship gave me a jump-start onto this whole graduate school process and I will always be grateful for your wise words and perspective.

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Strength correlation with residual ferrite fraction in 9CrODS ferritic steel

Cited by 11 publications

References 14 publications

Investigation of the relationships between mechanical properties and microstructure in a Fe-9%Cr ODS steel

Investigation of the relationships between mechanical properties and microstructure in a Fe-9%Cr ODS steel

Residual Ferrite Control of 9Cr ODS Steels by Tailoring Reverse Austenite Transformation

In Situ TEM Micropillar Compression Testing in Irradiated Oxide Dispersion Strengthened Alloys

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