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

2007 ◽  
Vol 558-559 ◽  
pp. 119-124
Author(s):  
Andrey Belyakov ◽  
Kaneaki Tsuzaki ◽  
Yoshisato Kimura ◽  
Yoshinao Mishima
Keyword(s):  
Stainless Steel ◽  
Low Temperature ◽  
Dislocation Density ◽  
Ambient Temperature ◽  
Ferritic Stainless Steel ◽  
Vickers Hardness ◽  
Subgrain Size ◽  
Large Strain ◽  
Internal Stresses ◽  
Cumulative Strain

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.

Nanostructure Evolution in an Austenitic Stainless Steel Subjected to Multiple Forging at Ambient Temperature

2010 ◽  
Vol 667-669 ◽  
pp. 553-558 ◽  
Author(s):  
Andrey Belyakov ◽  
Kaneaki Tsuzaki ◽  
Rustam Kaibyshev
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Ambient Temperature ◽  
Structural Changes ◽  
Subgrain Size ◽  
Large Strain ◽  
Total Strain ◽  
Large Strains ◽  
Fast Kinetics ◽  
Cumulative Strain

Deformation behavior and structural changes were studied in a 304-type austenitic stainless steel subjected to large strain multiple forging at an ambient temperature. The number of forging passes was 10, leading to the total cumulative strain of 4.0. The yield stress rapidly increased to about 1000 MPa after the first forging pass and then gradually approached a saturation level of about 2000 MPa in large strains. The grain/subgrain size decreased to about 50 nm at total strain of about 2. This grain/subgrain size reduced a little upon further processing; and comprised 35 nm after a total strain of 4.0. The fast kinetics for grain refinement was associated with deformation twinning and strain-induced martensitic transformation. The both of them resulted in fast grain subdivision at relatively small strains.

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

2007 ◽  
pp. 119-124
Author(s):  
Andrey Belyakov ◽  
Kaneaki Tsuzaki ◽  
Yoshisato Kimura ◽  
Yoshinao Mishima
Keyword(s):  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Large Strain

Influence of Plastic Pre-Strain on Low-Temperature Gas Carburization of 316L Austenitic Stainless Steel

2016 ◽  
Vol 853 ◽  
pp. 178-183 ◽  
Author(s):  
Ya Wei Peng ◽  
Jian Ming Gong ◽  
Yong Jiang ◽  
Ming Hui Fu ◽  
Dong Song Rong
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Low Temperature ◽  
Dislocation Density ◽  
Carbon Diffusion ◽  
Uniaxial Tensile ◽  
Engineering Strain ◽  
X Ray ◽  
316L Austenitic Stainless Steel

In this paper, the influence of pre-strain on low-temperature gas carburization of 316L austenitic stainless steel was investigated. A group of flat specimens were uniaxial tensile to several levels of pre-strain including 5%, 10%, 15%, 20% and 25% engineering strain. Then, the pre-strained specimens was treated by low-temperature gas carburization at 470 °C for 30 h. In order to elucidate the effect of pre-strain on low-temperature gas carburization, optical microscopy (OM), X-ray diffractometer (XRD), scanning electron probe micro-analyzer (EPMA), microhardness tester and residual stress analyzer were used. Meanwhile, dislocation density of the pre-strained specimens was semi-quantitatively measured by means of X-ray diffraction analysis and the role of dislocation density on carbon diffusion during low-temperature gas carburization was discussed. The results show as follow: (1) the thicknesses of the carburized layers are independent of the pre-strain degree. (2) dislocation density increases with the increasing pre-strain, but almost has no effect on carbon diffusion at the given carburizing temperature. (3) an outstanding surface with hardness (≈ 1150 HV0.1) and compressive residual stress (≈1900 MPa) is introduced by low-temperature gas carburization, and the strengthening results of carburization are unaffected by pre-strain.

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

2006 ◽  
Vol 503-504 ◽  
pp. 323-328 ◽  
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.

scholarly journals On the Strength of a 316L-Type Stainless Steel Subjected to Cold or Warm Rolling Followed by Annealing

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2116 ◽  
Author(s):  
Marina Odnobokova ◽  
Zhanna Yanushkevich ◽  
Rustam Kaibyshev ◽  
Andrey Belyakov
Keyword(s):  
Stainless Steel ◽  
Dislocation Density ◽  
Yield Strength ◽  
Large Strain ◽  
Warm Rolling ◽  
High Yield ◽  
Ultrafine Grained ◽  
Type Stainless Steel ◽  
Power Law Function ◽  
Continuous Recrystallization

The ultrafine-grained microstructures and their effect on the yield strength of a 316L-type austenitic stainless steel processed by large strain cold/warm rolling and subsequent annealing were studied. A kind of continuous recrystallization developed during annealing, resulting in the evolution of uniform ultrafine-grained microstructures with relatively high residual dislocation densities. The development of such microstructure at 973 K led to excellent combination of tensile properties including high yield strength (σ0.2 > 900 MPa) and satisfactory plasticity (δ > 15%). A unique power law function between the annealed grain size and the dislocation density with a dislocation density exponent of −0.5 was obtained for these continuously recrystallized microstructures. A physically justified explanation of the observed structural/substructural strengthening is introduced.

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