Strength of ultrafine-grained corrosion-resistant steels after severe plastic deformation

Rybalchenko, O. V.; Dobatkin, S. V.; Капуткина, Л. М.; Рааб, Г. И.; Krasil’nikov, N. A.

doi:10.1016/j.msea.2004.03.097

Cited by 44 publications

(22 citation statements)

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“…Thus, an alternative explanation may lie in the greater difficulty in reaching homogeneity in a material, such as steel, where the microstructure is complex. Recently, a deformation-induced martensitic transformation was observed in an austenitic steel [36] and accordingly it is reasonable to assume that some plastic energy is used for this transformation process. This suggests, therefore, that there may be insufficient energy in the central regions of disks of austenitic steel to effectively refine the microstructure.…”

Section: Discussionmentioning

confidence: 99%

Evolution of microstructure and microtexture in fcc metals during high-pressure torsion

2006

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Pure nickel and commercially pure (CP) aluminium were selected as model fcc materials for a detailed investigation of the experimental parameters influencing grain refinement and evolution of microstructure and microtexture during processing by highpressure torsion (HPT). Samples were examined after HPT using microhardness measurements, transmission electron microscopy and orientation imaging microscopy. Processing by HPT produces a grain size of 170 nm in pure Ni and~1 lm in CP aluminium. It is shown that homogeneous and equiaxed microstructures can be attained throughout the samples of nickel when using applied pressures of at least~6 GPa after 5 whole revolution. In CP aluminium, a homogeneous and equiaxed microstructure was achieved after 2 whole revolutions under an applied pressure of 1 GPa. For these conditions, the distributions of grain boundary misorientations are similar in the centre and at the periphery of the samples. It is shown that simple shear texture develops in fcc metals subjected to highpressure torsion. Some grain growth was detected at the periphery of the Al disk after 8 revolutions. The factors influencing the development of homogeneous microstructures in processing by HPT are discussed.

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Section: Discussionmentioning

confidence: 99%

Evolution of microstructure and microtexture in fcc metals during high-pressure torsion

2006

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Section: Resultsmentioning

confidence: 99%

“…After the ECAP at 400°C the microhardness of steels ASTM F138 and 08Kh18N10T increases by a factor of 1.7. As a rule, the lower hardening due to ECAP as compared to THP is associated with the sufficiently lower pressured used [10].The strain due to THP depends on the radius of the specimen. Therefore, we studied the distribution of microhardness over the diameter (Fig.…”

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confidence: 99%

Effect of Shear Strain on the Structure and Properties of Chromium-Nickel Corrosion-Resistant Steels

et al. 2015

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The structure and properties of metastable austenitic steel 08Kh18N10T and stable austenitic steel ASTM F138 under shear deformation implemented by torsion under hydrostatic pressure (THP) at T = 300 and 450°C and by equichannel angular pressing (ECAP) at T = 400°C are studied. The THP yields an ultrafine-grain structure in a fully austenitic matrix with grain size 45 -70 nm in steel ASTM F138 and 87 -123 nm in steel 08Kh1810T. The ECAP at 400°C yields a grain-subgrain structure with structural elements 100 -300 nm in size in steel 08Kh18N10T and 200 -400 nm in size in steel ASTM F138. INTRODUCTIONThe processes of shear deformation (SD) attract much interest due to the possibility of formation of an ultrafine-grain (UFG) (nano-and submicrocrystalline) structure responsible for enhancement of the strength and operating properties of metals [1 -4]. One of the methods, i.e., torsion under hydrostatic pressure (THP) [5,6], makes it possible to refine the structure ultimately without fracture of the specimen, to simulate structural and phase transformations in the course of the THP and to recommend deformation modes for massive specimens by the method of equichannel angular pressing (ECAP) [7,8]. In the present work we studied the possibility of refining the structure and elevating the mechanical properties of corrosion-resistant chromium-nickel steels after THP and ECAP under static and cyclic loading. The studied materials were a metastable austenitic steel 08Kh18N10T and a stable austenitic steel ASTM F138, which had been chosen due to the possible applicability in medicine. Cold deformation of steel 08Kh18N10T is accompanied by a martensitic transformation [9 -12], which promotes hardening but decreases the corrosion resistance. One of the tasks was to obtain in steel 08Kh18N10T after SD an ultrafine-grain structure in a completely austenitic state. For comparison we studied a stable austenitic steel ASTM F138 widely applied in medicine.The aim of the present work was to study structure formation in steels 08Kh18N10T and ASTM F138 during THP and ECAP and to determine the mechanical properties under static and cyclic loading of these steels in the ultrafine-grain condition. METHODS OF STUDYSpecimens of steels 08Kh18N10T and ASTM F138 (Table 1) were subjected to quenching from 1050°C for 1 h. After the quenching, the structure of steel 08Kh18N10T was represented by 5% d-ferrite and 95% austenite with grain size 20 mm; in steel ASTM F138 the grain size of the austenite was 60 mm (Fig. 1).Torsional deformation at a pressure of 6 GPa was allied to specimens with a diameter of 20 mm and a thickness of 1 mm. The true strain at the middle of the radius of the specimens was 5.7. The THP deformation was applied at a temperature of 300 and 450°C, which exceeded the temperature of the appearance of strain martensite. ECAP was applied to specimens with a length of 80 mm and a diameter of 20 mm at a temperature of 400°C over path Bc at the angle of intersection of the channels equal to 120°in six passes for steel 08Kh18N10T and...

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“…However, the ductility of such materials at room temperature is low due to the diminishing strain-hardening capacity and the inadequate strain-rate hardening. Recently, much effort has been spent on improving the ductility of materials with ultrafine grains by microstructure adjustment, e.g., pure copper maintaining the majority of the grains in a nanocrystalline to ultrafine range with some coarser grains, [1] Ti-based alloys with a composite microstructure of a nanostructured matrix and ductile dendritic phase, [2] Al-base alloy, [3] and plain carbon steels [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] manipulated by the dispersed secondphase particles. Particularly in the case of ultrafinegrained steels with average grain sizes of less than 1 lm, it has been proven that a certain uniform elongation can be obtained by the dispersion of martensite [4,5] or cementite.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, much effort has been spent on improving the ductility of materials with ultrafine grains by microstructure adjustment, e.g., pure copper maintaining the majority of the grains in a nanocrystalline to ultrafine range with some coarser grains, [1] Ti-based alloys with a composite microstructure of a nanostructured matrix and ductile dendritic phase, [2] Al-base alloy, [3] and plain carbon steels [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] manipulated by the dispersed secondphase particles. Particularly in the case of ultrafinegrained steels with average grain sizes of less than 1 lm, it has been proven that a certain uniform elongation can be obtained by the dispersion of martensite [4,5] or cementite. [6][7][8][9][10][11][12][13][14][15][16][17][18][19] Since an excellent combination of high yield strength and low ductile-brittle transition temperature can be achieved by grain refinement without any costly alloying, the improvement of the ductility of plain carbon steels with ultrafine grains has its advantage for the potential application in structural materials over the steels with high alloy contents.…”

Section: Introductionmentioning

confidence: 99%

Microstructure Evolution of a Pearlitic Steel during Hot Deformation of Undercooled Austenite and Subsequent Annealing

Wangyue

Sun

2008

Metall Mater Trans A

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Microstructure evolution of a pearlitic steel (0.81 mass pct C) during hot compression of undercooled austenite and subsequent annealing was studied by means of field-emission scanning electron microscopy, electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM). The experiments were performed at 923 K, between A 1 and Ar 1 , at strain rates of 0.01 to 1 s -1 . Compared with the isothermal transformation and the spheroidizing annealing, the transformation of undercooled austenite and the spheroidization of pearlite were accelerated by hot deformation, leading to the formation of the microduplex structures that consisted of ultrafine ferrite grains with average size smaller than 1 lm and spheroidized cementite particles with average size smaller than 0.3 lm during hot deformation and subsequent annealing.

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Strength of ultrafine-grained corrosion-resistant steels after severe plastic deformation

Cited by 44 publications

References 3 publications

Evolution of microstructure and microtexture in fcc metals during high-pressure torsion

Evolution of microstructure and microtexture in fcc metals during high-pressure torsion

Effect of Shear Strain on the Structure and Properties of Chromium-Nickel Corrosion-Resistant Steels

Microstructure Evolution of a Pearlitic Steel during Hot Deformation of Undercooled Austenite and Subsequent Annealing

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