Recovery in 15%Cr Ferritic Stainless Steel after Large Strain Deformation

15%Cr ferritic stainless steel was machined in rectangular samples and then processed by multiple forging to a total cumulative strain of 7.2 at an ambient temperature. The large strain deformation resulted in almost equiaxed submicrocrystalline structure with a mean grain/subgrain size of 230 nm and about 2.2×1014 m-2 dislocation density in grain/subgrain interiors. The annealing at a relatively low temperature of 500oC did not lead to any discontinuous recrystallizations. The grain/subgrain size and the interior dislocation density slightly changed to 240 nm and 2.1×1014 m-2, respectively, after annealing for 30 min, while the Vickers hardness decreased from 3140 MPa in the as-processed state to 2900 MPa. This annealing softening was attributed to remarkable release (by 50%) of internal stresses, which are associated with a non-equilibrium character of strain-induced grain/subgrain boundaries.

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On Structural Mechanism of Continuous Recrystallization in Ferritic Stainless Steel after Large Strain Processing

Materials Science Forum - Nanomaterials by Severe Plastic Deformation ◽

10.4028/0-87849-985-7.323 ◽

2006 ◽

pp. 323-328

Author(s):

Andrey Belyakov ◽

Yuuji Kimura ◽

Kaneaki Tsuzaki

Keyword(s):

Stainless Steel ◽

Ferritic Stainless Steel ◽

Large Strain ◽

Structural Mechanism ◽

Continuous Recrystallization

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On Structural Mechanism of Continuous Recrystallization in Ferritic Stainless Steel after Large Strain Processing

Materials Science Forum ◽

10.4028/www.scientific.net/msf.503-504.323 ◽

2006 ◽

Vol 503-504 ◽

pp. 323-328 ◽

Cited By ~ 3

Author(s):

Andrey Belyakov ◽

Yuuji Kimura ◽

Kaneaki Tsuzaki

Keyword(s):

Stainless Steel ◽

Grain Growth ◽

Ferritic Stainless Steel ◽

Large Strain ◽

Large Fraction ◽

Bar Rolling ◽

Structural Mechanism ◽

Annealing Behaviour ◽

Recovery Processes ◽

Continuous Recrystallization

The annealing behaviour of an Fe – 22%Cr – 3%Ni ferritic stainless steel processed by bar rolling/swaging to total strain of 4.4 at an ambient temperature was studied in the temperature range of 400 ~ 700oC. The annealing behaviour was characterised by the development of continuous recrystallization involving recovery processes followed by a normal grain growth. The large strain deformation caused the very fast recovery resulting in the development of almost equiaxed polygonized microstructure in place of the highly elongated deformation (sub)grains. The polygonization development was accompanied by some increase in the transverse (sub)grain size and the formation of many low-angle subboundaries. The latter ones could be composed from the dislocations, which were emitted by the strain-induced deformation (sub)boundaries. In spite of relatively large fraction of low-angle subboundaries, such polygonized microstructure was essentially stable against a discontinuous grain coarsening. Upon further annealing, therefore, the microstructure evolution was considered as a normal grain growth.

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Recovery and recrystallization in ferritic stainless steel after large strain deformation

Materials Science and Engineering A ◽

10.1016/j.msea.2005.05.057 ◽

2005 ◽

Vol 403 (1-2) ◽

pp. 249-259 ◽

Cited By ~ 38

Author(s):

A. Belyakov ◽

Y. Kimura ◽

K. Tsuzaki

Keyword(s):

Stainless Steel ◽

Ferritic Stainless Steel ◽

Large Strain

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Annealing behavior of a ferritic stainless steel subjected to large-strain cold working

Journal of Materials Research ◽

10.1557/jmr.2007.0398 ◽

2007 ◽

Vol 22 (11) ◽

pp. 3042-3051 ◽

Cited By ~ 22

Author(s):

A. Belyakov ◽

K. Tsuzaki ◽

Y. Kimura ◽

Y. Mishima

Keyword(s):

Stainless Steel ◽

Ferritic Stainless Steel ◽

Cold Working ◽

Large Strain ◽

Recrystallization Behavior ◽

Bar Rolling ◽

Annealing Behavior ◽

Ultrafine Grained ◽

Continuous Recrystallization ◽

Cold Strain

Mechanisms of microstructure evolution during annealing after cold working were studied in an Fe-15%Cr ferritic stainless steel, which was processed by bar rolling/swaging to various total strains ranging from 1.0 to 7.3 at ambient temperature. Two types of recrystallization behavior were observed depending on the cold strain. An ordinary primary (discontinuous) recrystallization developed in the samples processed to conventional strains of 1.0–2.0. On the other hand, rapid recovery at early annealing resulted in ultrafine-grained microstructures in the larger strained samples that continuously coarsened on further annealing. Such annealing behavior was considered as continuous recrystallization.

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