Mechanical Properties of Bulk Ultrafine Grained Aluminum Fabricated by Torsion Deformation at Various Temperatures and Strain Rates

Khamsuk, Sunisa; Park, Nokeun; Gao, Si; Terada, Daisuke; Adachi, Hiroki; Tsuji, Nobuhiro

doi:10.2320/matertrans.ma201321

Cited by 17 publications

(6 citation statements)

References 20 publications

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“…Note here that s 0 of about 200 MPa has been reported for various stainless steels, [11,[25][26][27][28] and a of 0.6-0.7 is frequently used parameter to account the dislocation strengthening. [15,29,30] However, the value of K e ¼ 0.047 MPa m 0.5 is remarkably smaller than K y values of 0.15-0.4, which have been reported for Hall-Petch relationship. [11,28,[31][32][33] A decrease in the slope in Hall-Petch relationship has been observed in other studies on submicrocrystalline/nanocrystalline steels processed by large strain deformation.…”

Section: Strengthening Mechanismsmentioning

confidence: 54%

Effect of Severe Cold or Warm Deformation on Microstructure Evolution and Tensile Behavior of a 316L Stainless Steel

2015

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The deformation microstructures and mechanical properties of a 316L austenitic stainless steel subjected to large strain cold or warm plate rolling are studied. The cold or warm rolling was carried out at room temperature or 573 K, respectively, to different total true strains up to 3. The structural changes are characterized by the development of nanocrystalline structures with the transverse grain size of about 80 or 160 nm at room temperature or 573 K, respectively. The evolution of nanocrystalline structure under cold working conditions (room temperature) is assisted by the development of mechanical twinning and partial martensitic transformation that result in rapid grain refinement. The development of nanocrystalline structures during cold/warm working is accompanied by significant strengthening. The yield strength approaches 1 680 or 1 070 MPa after cold or warm rolling to a total strain of 3, respectively.

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Section: Strengthening Mechanismsmentioning

confidence: 54%

Effect of Severe Cold or Warm Deformation on Microstructure Evolution and Tensile Behavior of a 316L Stainless Steel

2015

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“…Thus, using the dislocation density as single structural parameter to evaluate the strength of the present warm rolled steels with complicated deformation microstructures seems to be oversimplified. Good agreement between actual and predicted yield strength (σ0.2) has been obtained by modification of the Hall-Petch relationship, incorporating substructural strengthening aroused by high dislocation density (ρε) in addition to grain boundary strengthening expressed by the mean deformation grain size (Dε) [50,51]:…”

Section: Strengthening Mechanismsmentioning

confidence: 95%

Microstructural Changes and Strengthening of Austenitic Stainless Steels during Rolling at 473 K

Odnobokova

Belyakov

Enikeev

et al. 2020

Metals

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The microstructural changes in 304L and 316L austenitic stainless steels during plate rolling with 95% rolling reduction at a temperature of 473 K and their effect on strengthening were studied. The microstructure evolution was associated with deformation twinning and microshear banding. The latter ones involved ultrafine crystallites, which rapidly evolved in strain-induced ultrafine austenite grains as a result of fast increase in misorientations between them. Besides the ultrafine austenite crystallite evolution, the microshear bands assisted local appearance of deformation martensite, which attained about 25 vol.% and 3 vol.% at total strain of 3 in 304L and 316L steels, respectively. Both the microshear banding and the martensitic transformation promoted the formation of ultrafine grains with a size of less than 1 µm. The strain dependence of the ultrafine grain fraction obeyed a modified Johnson-Mehl-Avrami-Kolmogorov function. The deformation grain size and dislocation density that develop during rolling could also be expressed by exponential functions of true strain. Incorporating the revealed relationships between the strain and the microstructural parameters into modified Hall–Petch-type equation, unique expression for the yield strength of processed steels was obtained. The dislocation strengthening was the largest contributor to the strength, especially at small to medium strains, although grain size strengthening increased during rolling approaching that from dislocations at large strains.

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“…Thus, the value of α = 0.73 is obtained from Figure 7. It should be noted that almost the same values of α have been used for calculation of dislocation strengthening in various alloys [19][20][21][30][31][32]. Finally, the following expression for the yield strength of the present steel subjected to cold rolling can be obtained: …”

Section: Strengthening Mechanismsmentioning

confidence: 99%

Development of Nanocrystalline 304L Stainless Steel by Large Strain Cold Working

Odnobokova

Belyakov

Kaibyshev

2015

Metals

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Abstract:The microstructural changes leading to nanocrystalline structure development and the respective tensile properties were studied in a 304L stainless steel subjected to large strain cold rolling at ambient temperature. The cold rolling was accompanied by the development of deformation twinning and martensitic transformation. The latter readily occurred at deformation microshear bands, leading the martensite fraction to approach 0.75 at a total strain of 3. The deformation twinning followed by microshear banding and martensitic transformation promoted the development of nanocrystalline structure consisting of a uniform mixture of austenite and martensite grains with their transverse sizes of 120-150 nm. The developed nanocrystallites were characterized by high dislocation density in their interiors of about 3 × 10 15 m −2 and 2 × 10 15 m −2 in austenite and martensite, respectively. The development of nanocrystalline structures with high internal stresses led to significant strengthening. The yield strength increased from 220 MPa in the original hot forged state to 1600 MPa after cold rolling to a strain of 3.

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Mechanical Properties of Bulk Ultrafine Grained Aluminum Fabricated by Torsion Deformation at Various Temperatures and Strain Rates

Cited by 17 publications

References 20 publications

Effect of Severe Cold or Warm Deformation on Microstructure Evolution and Tensile Behavior of a 316L Stainless Steel

Effect of Severe Cold or Warm Deformation on Microstructure Evolution and Tensile Behavior of a 316L Stainless Steel

Microstructural Changes and Strengthening of Austenitic Stainless Steels during Rolling at 473 K

Development of Nanocrystalline 304L Stainless Steel by Large Strain Cold Working

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