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 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 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.

Grain Boundary Structure and Deformation Defects in Nanostructured Al–Mg Alloys Processed by High Pressure Torsion

2008 ◽  
Vol 584-586 ◽  
pp. 528-534 ◽  
Author(s):  
M. Liu ◽  
Hans Jørgen Roven ◽  
Tamás Ungár ◽  
L. Balogh ◽  
Maxim Yu. Murashkin ◽  
...  
Keyword(s):  
High Pressure ◽  
Grain Boundary ◽  
Line Profile ◽  
High Pressure Torsion ◽  
Boundary Structure ◽  
X Ray ◽  
Grain Boundary Structure ◽  
Average Grain Size ◽  
Deformation Defects ◽  
Non Equilibrium

An Al–0.5 Mg alloy and a commercial AA5182 alloy were subjected to high pressure torsion (HPT) to five turns under pressure of 6 GPa at room temperature. The grain boundary structure and deformation defects were investigated after HPT using high-resolution transmission electron microscopy (HRTEM). Low-angle, high-angle, equilibrium and non-equilibrium grain/subgrain boundaries, twin boundaries, full dislocations, dipoles, microtwins and stacking faults were identified by HRTEM. Extrinsic 60° dislocations in the form of dipoles were frequently observed in non-equilibrium grain/subgrain boundaries. In addition subgrain size distributions and dislocation densities were quantified by x-ray line profile analysis. It was observed that the average grain size decreased from about 120 nm to 55 nm as the Mg content increased from 0.5 to 4.1 wt%. Concomitantly the average stored dislocation density increased from 1.7 to 12.8  1014 m-2. Based on the HRTEM investigations and the x-ray line profile analyses, the deformation mechanism associated with the typical grain boundaries and deformation defects in the aluminium alloys were discussed.

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.

Peculiarities in the Texture Formation of Intermetallic Compounds Deformed by High Pressure Torsion

2014 ◽  
Vol 1760 ◽  
Author(s):  
Christine Tränkner ◽  
Aurimas Pukenas ◽  
Jelena Horky ◽  
Michael Zehetbauer ◽  
Werner Skrotzki
Keyword(s):  
High Pressure ◽  
High Pressure Torsion ◽  
Electron Backscatter Diffraction ◽  
High Energy ◽  
X Ray ◽  
Local Texture ◽  
Large Rotations ◽  
Electron Backscatter ◽  
Shear Strains ◽  
Backscatter Diffraction

ABSTRACTNiAl, YCu and TiAl polycrystals with B2 and L10 structure, respectively, have been deformed by high pressure torsion (HPT) at temperatures between 20°C and 500°C at a hydrostatic pressure of 8 GPa to high shear strains. Local texture measurements were done by diffraction of high-energy synchrotron radiation and X-ray microdiffraction. In addition, the microstructure was analyzed by electron backscatter diffraction (EBSD). Besides typical shear components an oblique cube component is observed with quite large rotations about the transverse direction. Based on the temperature dependence of this component as well as on microstructure investigations it is concluded that it is formed by discontinuous dynamic recrystallization. The influence of high pressure on recrystallization of intermetallics at low temperatures is discussed.

Static Recrystallization and Texture Evolution of 316L Stainless Steel Fibers

2014 ◽  
Vol 1052 ◽  
pp. 45-50 ◽  
Author(s):  
Hai Ou Yu ◽  
Yan Wang ◽  
Yong Liu ◽  
Hui Ping Tang
Keyword(s):  
Stainless Steel ◽  
Grain Growth ◽  
316L Stainless Steel ◽  
Texture Evolution ◽  
Optical Microscope ◽  
Steel Fibers ◽  
X Ray ◽  
Average Grain Size ◽  
Before And After ◽  
Growth Equations

By isothermal annealing tests, the recrystallization and grain growth behaviors of 316L stainless steel fibers with a diameter of 8 μm were investigated using the optical microscope (OM), scanning electron microscope (SEM) and X-ray texture analysis methods. The average grain size of the fibers with a diameter of 8 μm annealed at different conditions was quantitatively measured. The grain growth equations of the fibers were constructed, and the activation energies for grain growth of the fibers were also determined. Meanwhile, efforts have been paid on analyzing the texture evolution of 316L stainless steel fibers before and after annealing.

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