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.

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.

scholarly journals Evolution of microstructure and hardness during artificial aging of an ultrafine-grained Al-Zn-Mg-Zr alloy processed by high pressure torsion

2020 ◽  
Vol 55 (35) ◽  
pp. 16791-16805
Author(s):  
Jenő Gubicza ◽  
Moustafa El-Tahawy ◽  
János L. Lábár ◽  
Elena V. Bobruk ◽  
Maxim Yu Murashkin ◽  
...  
Keyword(s):  
High Pressure ◽  
Dislocation Density ◽  
Grain Boundaries ◽  
Artificial Aging ◽  
High Pressure Torsion ◽  
Secondary Phase ◽  
Aging Effect ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Evolution Of Microstructure

Abstract An ultrafine-grained (UFG) Al-4.8%Zn-1.2%Mg-0.14%Zr (wt%) alloy was processed by high pressure torsion (HPT) technique and then aged at 120 and 170 °C for 2 h. The changes in the microstructure due to this artificial aging were studied by X-ray diffraction and transmission electron microscopy. It was found that the HPT-processed alloy has a small grain size of about 200 nm and a high dislocation density of about 8 × 1014 m−2. The majority of precipitates after HPT are Guinier–Preston (GP) zones with a size of ~ 2 nm, and only a few large particles were formed at the grain boundaries. Annealing at 120 and 170 °C for 2 h resulted in the formation of stable MgZn2 precipitates from a part of the GP zones. It was found that for the higher temperature the fraction of the MgZn2 phase was larger and the dislocation density in the Al matrix was lower. The changes in the precipitates and the dislocation density due to aging were correlated to the hardness evolution. It was found that the majority of hardness reduction during aging was caused by the annihilation of dislocations and some grain growth at 170 °C. The aging effect on the microstructure and the hardness of the HPT-processed specimen was compared to that observed for the UFG sample processed by equal-channel angular pressing. It was revealed that in the HPT sample less secondary phase particles formed in the grain boundaries, and the higher amount of precipitates in the grain interiors resulted in a higher hardness even after aging.

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.

The Effect of High Pressure Torsion on Structural Refinement and Mechanical Properties of an Austenitic Stainless Steel

2013 ◽  
Vol 13 (5) ◽  
pp. 3246-3249 ◽  
Author(s):  
Agnieszka Teresa Krawczynska ◽  
Malgorzata Lewandowska ◽  
Reinhard Pippan ◽  
Krzysztof Jan Kurzydlowski
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
High Pressure Torsion ◽  
Structural Refinement

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.

Microstructure and mechanical properties of ultrafine-grained aluminum consolidated by high-pressure torsion

2017 ◽  
Vol 682 ◽  
pp. 501-508 ◽  
Author(s):  
Mohammad Khajouei-Nezhad ◽  
Mohammad Hossein Paydar ◽  
Ramin Ebrahimi ◽  
Péter Jenei ◽  
Péter Nagy ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
High Pressure Torsion ◽  
Microstructure And Mechanical Properties ◽  
Ultrafine Grained

Microstructure and Mechanical Properties of Ultrafine-Grained Mg-Zn-Ca Alloy

2017 ◽  
Vol 381 ◽  
pp. 39-43 ◽  
Author(s):  
Olya B. Kulyasova ◽  
Rinat K. Islamgaliev ◽  
Ruslan Z. Valiev
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
High Pressure ◽  
Chemical Composition ◽  
High Pressure Torsion ◽  
Notable Effect ◽  
Ultrafine Grained ◽  
Mean Grain Size ◽  
High Microhardness ◽  
Mean Size

This paper studies the structure and mechanical properties of the Mg-1%Zn-xCa system subjected to high-pressure torsion (HPT) treatment. It was found that the chemical composition had a notable effect on the processes of grain refinement in the alloy. As is shown, HPT of Mg-1%Zn-0.005%Ca resulted in the formation of grains with a mean size of 250 nm, while HPT of the alloy with an increased content of Са up to 0.2% led to the formation of a nanostructure with a mean grain size of 90 nm. It is demonstrated that high microhardness is typical of all HPT-processed samples. The formation of fine Mg2Ca particles was established to increase the heat resistance of the alloy.

Emission Nuclear Gamma-Resonance Spectroscopy of Grain Boundaries in Coarse-Grained and Ultrafine-Grained Polycrystalline Mo

2015 ◽  
Vol 364 ◽  
pp. 147-156 ◽  
Author(s):  
Vladimir V. Popov ◽  
A.V. Sergeev ◽  
A.V. Stolbovsky
Keyword(s):  
High Pressure ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
High Pressure Torsion ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Coarse Grained ◽  
Resonance Spectroscopy ◽  
Nuclear Gamma Resonance ◽  
Ultrafine Grained

Grain boundaries in coarse-grained Mo with grain boundaries of recrystallization origin and in ultrafine-grained (UFG) Mo obtained by high pressure torsion have been studied by the emission Mössbauer spectroscopy on the57Co (57Fe) nuclei. It is demonstrated that Co atoms diffuse along grain boundaries by interstitials. The temperature dependence of grain-boundary segregation factor of Co in coarse-grained Mo has been determined. It is shown that the state of Co atoms in grain boundaries and near-boundary areas in UFG Mo differs from that in coarse-grained Mo.

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