scholarly journals Stored energy in ultrafine-grained 316L stainless steel processed by high-pressure torsion

2017 ◽  
Vol 6 (4) ◽  
pp. 339-347 ◽  
Author(s):  
Moustafa El-Tahawy ◽  
Yi Huang ◽  
Taekyung Um ◽  
Heeman Choe ◽  
János L. Lábár ◽  
...  
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
316L Stainless Steel ◽  
High Pressure Torsion ◽  
Stored Energy ◽  
Ultrafine Grained

scholarly journals Influence of High-Pressure Torsion on the Microstructure and Microhardness of Additively Manufactured 316L Stainless Steel

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1553
Author(s):  
Shahir Mohd Mohd Yusuf ◽  
Ying Chen ◽  
Nong Gao
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Stainless Steel ◽  
316L Stainless Steel ◽  
High Pressure Torsion ◽  
X Ray ◽  
Average Hardness ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
Shear Strains

High-pressure torsion (HPT) is known as an effective severe plastic deformation (SPD) technique to produce bulk ultrafine-grained (UFG) metals and alloys by the application of combined compressive force and torsional shear strains on thin disk samples. In this study, the microstructures and microhardness evolution of an additively manufactured (AM) 316L stainless steel (316L SS) processed through 5 HPT revolutions are evaluated at the central disk area, where the effective shear strains are relatively low compared to the peripheral regions. Scanning electron microscopy (SEM) analysis showed that the cellular network sub-structures in AM 316L SS were destroyed after 5 HPT revolutions. Transmission electron microscopy (TEM) observations revealed non-equilibrium ultrafine grained (UFG) microstructures (average grain size: ~115 nm) after 5 revolutions. Furthermore, energy dispersive x-ray spectroscopy (EDX) analysis suggested that spherical Cr-based nano-silicates are also found in the as-received condition, which are retained even after HPT processing. Vickers microhardness (HV) measurements indicated significant increase in average hardness values from ~220 HV before HPT processing to ~560 HV after 5 revolutions. Quantitative X-ray diffraction (XRD) patterns exhibit a considerable increase in dislocation density from ~0.7 × 1013 m−2 to ~1.04 × 1015 m−2. The super-high average hardness increment after 5 HPT revolutions is predicted to be attributed to the UFG grain refinement, significant increase in dislocation densities and the presence of the Cr-based nano-silicates, according to the model established based on the linear additive theory.

scholarly journals Microstructure, phase composition and hardness evolution in 316L stainless steel processed by high-pressure torsion

2016 ◽  
Vol 657 ◽  
pp. 215-223 ◽  
Author(s):  
Jenő Gubicza ◽  
Moustafa El-Tahawy ◽  
Yi Huang ◽  
Hyelim Choi ◽  
Heeman Choe ◽  
...  
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
Phase Composition ◽  
316L Stainless Steel ◽  
High Pressure Torsion

Thermal Stability of Ultrafine-Grained Pure Titanium Processed by High-Pressure Torsion

2021 ◽  
Vol 1016 ◽  
pp. 338-344
Author(s):  
Wan Ji Chen ◽  
Jie Xu ◽  
De Tong Liu ◽  
De Bin Shan ◽  
Bin Guo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Grain Size ◽  
High Pressure ◽  
Annealing Temperature ◽  
High Pressure Torsion ◽  
Stored Energy ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
Thermal Stability Of

High-pressure torsion (HPT) was conducted under 6.0 GPa on commercial purity titanium up to 10 turns. An ultrafine-grained (UFG) pure Ti with an average grain size of ~96 nm was obtained. The thermal properties of these samples were studied by using differential scanning calorimeter (DSC) which allowed the quantitative determination of the evolution of stored energy, the recrystallization temperatures, the activation energy involved in the recrystallization of the material and the evolution of the recrystallized fraction with temperature. The results show that the stored energy increases, beyond which the stored energy seems to level off to a saturated value with increase of HPT up to 5 turns. An average activation energy of about 101 kJ/mol for the recrystallization of 5 turns samples was determined. Also, the thermal stability of the grains of the 5 turns samples with subsequent heat treatments were investigated by microstructural analysis and Vickers microhardness measurements. It is shown that the average grain size remains below 246 nm when the annealing temperature is below 500 °C, and the size of the grains increases significantly for samples at the annealing temperature of 600 °C.

Submicrocrystalline Austenitic Stainless Steel Processed by Cold or Warm High Pressure Torsion

2016 ◽  
Vol 838-839 ◽  
pp. 398-403 ◽  
Author(s):  
Marina Tikhonova ◽  
Nariman Enikeev ◽  
Ruslan Z. Valiev ◽  
Andrey Belyakov ◽  
Rustam Kaibyshev
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Severe Plastic Deformation ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Submicrocrystalline Structure ◽  
Ultrafine Grained ◽  
Different Temperatures

The formation of submicrocrystalline structure during severe plastic deformation and its effect on mechanical properties of an S304H austenitic stainless steel with chemical composition of Fe – 0.1C – 0.12N – 0.1Si – 0.95Mn – 18.4Cr – 7.85Ni – 3.2Cu – 0.5Nb – 0.01P – 0.006S (all in mass%) were studied. The severe plastic deformation was carried out by high pressure torsion (HPT) at two different temperatures, i.e., room temperature or 400°C. HPT at room temperature or 400°C led to the formation of a fully austenitic submicrocrystalline structure. The grain size and strength of the steels with ultrafine-grained structures produced by cold or warm HPT were almost the same. The ultimate tensile strengths were 1950 MPa and 1828 MPa after HPT at room temperature and 400°C, respectively.

scholarly journals Effect of Annealing Temperature on the Microstructure and Mechanical Properties of High-Pressure Torsion-Produced 316LN Stainless Steel

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 181
Author(s):  
Yuanyuan Dong ◽  
Zhe Zhang ◽  
Zhihai Yang ◽  
Ruixiao Zheng ◽  
Xu Chen
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Stainless Steel ◽  
Grain Boundaries ◽  
Annealing Temperature ◽  
High Pressure Torsion ◽  
Annealing Process ◽  
Σ Phase ◽  
316Ln Stainless Steel ◽  
Ultrafine Grained

316LN stainless steel is a prospective structural material for the nuclear and medical instruments industries. Severe plastic deformation (SPD) combined with annealing possesses have been used to create materials with excellent mechanical properties. In the present work, a series of ultrafine-grained (UFG) 316LN steels were produced by high-pressure torsion (HPT) and a subsequent annealing process. The effects of annealing temperature on grain recrystallization and precipitation were investigated. Recrystallized UFG 316LN steels can be achieved after annealing at high temperature. The σ phase generates, at grain boundaries, at an annealing temperature range of 750–850 °C. The dislocations induced by recrystallized grain boundaries and strain-induced nanotwins are beneficial for enhancing ductility. Moreover, microcracks are easy to nucleate at the σ phase and the γ-austenite interface, causing unexpected rapid fractures.

Structural evolution during nanostructuring of additive manufactured 316L stainless steel by high-pressure torsion

2021 ◽  
pp. 130364
Author(s):  
Jae-Kyung Han ◽  
Xiaojing Liu ◽  
Isshu Lee ◽  
Yulia O. Kuzminova ◽  
Stanislav A. Evlashin ◽  
...  
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
316L Stainless Steel ◽  
High Pressure Torsion ◽  
Structural Evolution

Evolution of Microstructure, Phase Composition and Hardness in 316L Stainless Steel Processed by High-Pressure Torsion

2016 ◽  
Vol 879 ◽  
pp. 502-507 ◽  
Author(s):  
Moustafa El-Tahawy ◽  
Jenő Gubicza ◽  
Yi Huang ◽  
Hye Lim Choi ◽  
Hee Man Choe ◽  
...  
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
Phase Composition ◽  
316L Stainless Steel ◽  
High Pressure Torsion ◽  
Martensite Phase ◽  
Initial Material ◽  
Disk Radius ◽  
316L Austenitic Stainless Steel ◽  
Evolution Of Microstructure

The evolution of phase composition, microstructure and hardness in 316L austenitic stainless steel processed by high-pressure torsion (HPT) was studied up to 20 turns. It was revealed that simultaneous grain refinement and phase transformation occur during HPT-processing. The γ-austenite in the initial material transformed gradually to ɛ-and α’-martensites due to deformation. After 20 turns of HPT the main phase was α’-martensite. The initial grain size of ~42 μm was refined to ~48 nm while the dislocation density increased to ~143 × 1014 m-2 in the α’-martensite phase at the disk periphery processed by 20 turns. The microstructure and hardness along the disk radius became more homogeneous with increasing numbers of turns. An approximately homogeneous hardness distribution with a saturation value of ~6140 MPa was achieved in 20 turns.

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