High-Strain Rate Superplasticity and Role of Dynamic Recrystallization in a Superplastic Duplex Stainless Steel

Tsuzaki, Kaneaki; Matsuyama, Hirofumi; Nagao, Masato; Maki, Tadashi

doi:10.2320/matertrans1989.31.983

Cited by 61 publications

(26 citation statements)

References 19 publications

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“…For larger deformation, the original grains become more elongated along the rolling direction and, consequently, received a larger grain refinement effect. The similar explanation also presented by Tsuzaki 21) in studying the superplasticity of a duplex stainless steel. Their research indicated that the dynamic recrystallization would take place during hot deformation, and that the role of dynamic recrystallization is to make the fine structure suitable for the grain boundary sliding in the early stage of deformation.…”

Section: Microstructuressupporting

confidence: 52%

Influence of Hot Rolling and Post-Tempering on the Mechanical Properties of Duplex Stainless Steel Containing Martensite and Ferrite

Wen

2006

Mater. Trans.

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In this research, SUS 403 duplex stainless steel containing martensite and ferrite was processed with hot rolling at a range of reductions (15-50%) and post-tempering at a range of temperatures (473-873 K) to investigate microstructural change during tempering and mechanical properties as a function of tempering temperature and ferrite grain size. The results indicate that Cr-rich carbides precipitate when tempering at the range of 473-773 K. The precipitation of fine carbides increases the carbide-ferrite phase boundary area. Again, the hard carbides reinforce the ferrite matrix along the boundaries and, consequently, results in enhancing mechanical properties. A secondary strengthening phenomenon in stress and hardness occurs at 773 K tempered. The ferrite grain size decreases with increasing reduction. Fine grain structure leads to an increase in grain boundaries and homogeneous dispersion of carbides, which provides a dominant action against crack propagation and improves the mechanical properties. Except the hardness, the maximum mechanical properties of each rolling reduction are better than that of the specimens quenched and tempered without hot rolling.

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Section: Microstructuressupporting

confidence: 52%

Influence of Hot Rolling and Post-Tempering on the Mechanical Properties of Duplex Stainless Steel Containing Martensite and Ferrite

Wen

2006

Mater. Trans.

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“…A cold-rolled fully-ferritic duplex steel followed by annealing in the two-phase field produces the typical microduplex structure, in which the ¡ matrix is in a recovered condition, as subgrains with fairly low misorientations. 5,6) Tsuzaki et al 5) showed that the angle of misorientation of ¡ subgrain boundaries shows gradual increase with straining, by dynamic recovery, through the continuous migration of the accumulated dislocations to the subgrain boundaries; when the misorientations become high enough, superplastic grain sliding starts to occur.…”

Section: 3)mentioning

confidence: 99%

“…Moreover, the microduplex structure, a refined structure obtained by specific thermo-mechanical processing, has been shown to exhibit superplasticity due to the shape, size and dispersion of the £-phase precipitates. 4,5) The current study aims to apply the Harmonic structure design to a SUS 329J1 two-phase stainless steel, and to take advantage of the superplastic behavior of the microduplex structure in order to produce a high-strength duplex stainless steel that retains good plasticity.…”

Section: Introductionmentioning

confidence: 99%

Harmonic Structure Design of a SUS329J1 Two Phase Stainless Steel and Its Mechanical Properties

et al. 2013

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In the pursuit of creating new structures with improved overall mechanical properties, we produced a duplex stainless steel with both high strength and good plasticity, which combines in a harmonized way a refined microduplex structure with a coarse structure. This is accomplished by applying a mixed process of mechanical milling followed by spark-plasma sintering for a duplex steel powder, leading to a microstructure with a gradual and continuous transition between coarse and ultra-fine-grained regions at the microscale. This type of structure is referred to as Harmonic. The grain refinement at the surface of the milled powder particles occurs through the recrystallization of the severely-deformed surface layers during sintering, and results in a microduplex structure which gradually transitions to a coarse duplex structure away from the particles surface. Both the recrystallization mechanism and the effect of this refined structure on the sinterability and final mechanical properties of the compacts are investigated.

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“…[5][6][7] This process causes misorientation among the cells to increase and results in conversion of dislocation cells into grains with medium to high angle grain boundaries during LSR deformation. Tsuzaki et al have observed similar behavior in 25Cr-7Ni -3Mo ferrite/austenite duplex steel at 1000 ± C. 8 An ultrafine grain microstructure (grain size ഠ200 nm) can be formed in bulk 304 stainless by a deformation-based processing technique that does not require powder precursors. In addition, this processing requires only 95% (e 3) total strain and is amenable to scale up.…”

mentioning

confidence: 70%

Processing of submicron grain 304 stainless steel

Jain

Christman

1996

J. Mater. Res.

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A novel thermomechanical processing technique for the synthesis of bulk submicron grain (grain size ഠ200 nm) 304 stainless steel is reported. This ingot-metallurgical technique requires a total deformation of only 95%, and the key steps to this processing technique involve (i) formation of ultrafine dislocation cell structure, and (ii) the conversion of dislocation cells into grains with medium to high misorientation by grain boundary sliding.Materials with submicron grain microstructure exhibit significantly improved mechanical properties over their course grain counterparts.1 These properties include higher strength, improved formability and ductility, and reduced superplastic temperature.2 However, due to metastable nature of these microstructures, submicron grain materials are difficult to produce in bulk form and are usually produced by special powder metallurgical techniques. 3,4 There is a considerable interest in nonpowder metallurgical techniques for the production of these materials, because the problem of residual porosity can be completely avoided by the use of these techniques.1 Here, we describe a novel processing technique for the production of a submicron grain (200 nm) 304 stainless steel (304 SS) by an ingot metallurgical route. This processing technique does not require any powder precursors and requires a total deformation of only 95%. The key steps to this technique involve (i) generation of a dislocation cell structure of same size (or finer) to finally desired grain size, and (ii) activation of grain boundary sliding in this microstructure, leading to conversion of dislocation cells into grains with high angle boundaries. This processing technique is based on our previous work where we observed the collapse of microstructure in Fe -28Al-2Cr intermetallic compound from 80 nm to 10 nm during room temperature compressive deformation. 4 The starting material for this investigation was a commercial grade 304 stainless steel (304 SS) with an average grain size of ഠ200 mm. The x-ray diffraction (XRD) pattern of the as-received stainless steel is shown in Fig. 1. The microstructure consists of a mixture of bcc a) Present address: Gillette R&D, Gillette Park, Boston, Massachusetts 02106-2131.and fcc phases as peaks from both bcc and fcc phases are visible in the x-ray diffraction pattern. The 304 SS rod (3͞8″ in diam) was initially rolled 63% at room temperature to an ingot with square cross section. This ingot was further rolled 65% at liquid nitrogen temperature, which resulted in reduction of cross section to 0.120 in. 3 0.120 in. The ingot obtained in this manner will be referred to as SS8 in the rest of this paper.The microstructure of the SS8 ingot was examined by transmission electron microscopy (TEM) and x-ray diffraction in both directions, i.e., in the planes parallel and perpendicular to the axis of rolling. X-ray diffraction scan of this ingot as shown in Fig. 1 reveals that the microstructure consists entirely of bcc phase. The microstructure of SS8 ingot as examined by TEM is shown in...

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High-Strain Rate Superplasticity and Role of Dynamic Recrystallization in a Superplastic Duplex Stainless Steel

Cited by 61 publications

References 19 publications

Influence of Hot Rolling and Post-Tempering on the Mechanical Properties of Duplex Stainless Steel Containing Martensite and Ferrite

Influence of Hot Rolling and Post-Tempering on the Mechanical Properties of Duplex Stainless Steel Containing Martensite and Ferrite

Harmonic Structure Design of a SUS329J1 Two Phase Stainless Steel and Its Mechanical Properties

Processing of submicron grain 304 stainless steel

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