scholarly journals Creep Resistance of S304H Austenitic Steel Processed by High-Pressure Sliding

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 331
Author(s):  
Petr Kral ◽  
Jiri Dvorak ◽  
Vaclav Sklenicka ◽  
Zenji Horita ◽  
Yoichi Takizawa ◽  
...  
Keyword(s):  
High Pressure ◽  
Austenitic Steel ◽  
Creep Behavior ◽  
Creep Strength ◽  
Coarse Grained ◽  
Σ Phase ◽  
Ultrafine Grained ◽  
Mean Grain Size ◽  
Ultrafine Grained Microstructure ◽  
Thermal Stability Of

Sheets of coarse-grained S304H austenitic steel were processed by high-pressure sliding (HPS) at room temperature and a ultrafine-grained microstructure with a mean grain size of about 0.14 µm was prepared. The microstructure changes and creep behavior of coarse-grained and HPS-processed steel were investigated at 500–700 °C under the application of different loads. It was found that the processing of S304H steel led to a significant improvement in creep strength at 500 °C. However, a further increase in creep temperature to 600 °C and 700 °C led to the deterioration of creep behavior of HPS-processed steel. The microstructure results suggest that the creep behavior of HPS-processed steel is associated with the thermal stability of the SPD-processed microstructure. The recrystallization, grain growth, the coarsening of precipitates led to a reduction in creep strength of the HPS-processed state. It was also observed that in the HPS-processed microstructure the fast formation of σ-phase occurs. The σ-phase was already formed during slight grain coarsening at 600 °C and its formation was enhanced after recrystallization at 700 °C.

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.

Structuration of Refractory Metals Tantalum and Niobium Using Modified Equal Channel Angular Pressing Technique

2019 ◽  
Vol 799 ◽  
pp. 103-108 ◽  
Author(s):  
Lembit Kommel ◽  
Babak Shahreza Omranpour ◽  
Valdek Mikli
Keyword(s):  
Equal Channel Angular Pressing ◽  
Coarse Grained ◽  
Uniaxial Tensile ◽  
Modified Technique ◽  
Uniaxial Tensile Strength ◽  
Large Samples ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Von Mises ◽  
Ultrafine Grained Microstructure

In the present work, we use a modified Equal Channel Angular Pressing technique for structure and properties change of Tantalum and Niobium at room temperature. The main advantage of this modified technique is the possibility to produce relatively large samples with ultrafine-grained microstructure in all volume of the workpiece by reduced deformation load up to 25% via friction decrease, and also to prevent the punch fracture under high compression stress during pressing. The various microstructures and properties were produced in metals by using different von Mises strain levels up to ƐvM = 13.8. The changes in microstructure were studied by using SEM and TEM techniques. The change of mechanical properties was measured by using various tension and hardness testing setups. We can conclude that during processing the ultrafine-grained microstructure in as-cast Nb and Ta was formed. The uniaxial tensile strength, Vickers hardness, and plasticity of Nb and Ta significantly increased as compared to coarse-grained counterparts. We believe that the relatively large workpieces of pure bulk Ta and Nb metals with improved microstructure and exploitation properties are suitable materials for the modern industry.

Nanoindentation creep behavior of coarse-grained and ultrafine-grained pure magnesium and AZ31 alloy

2017 ◽  
Vol 698 ◽  
pp. 348-355 ◽  
Author(s):  
Jiangjiang Hu ◽  
Wei Zhang ◽  
Guangli Bi ◽  
Jinwen Lu ◽  
Wangtu Huo ◽  
...  
Keyword(s):  
Creep Behavior ◽  
Az31 Alloy ◽  
Pure Magnesium ◽  
Coarse Grained ◽  
Ultrafine Grained

Enhanced Thermal Stability and Mechanical Properties of Ultrafine-Grained Aluminum Alloy

2010 ◽  
Vol 667-669 ◽  
pp. 331-336 ◽  
Author(s):  
Rinat K. Islamgaliev ◽  
Marina A. Nikitina ◽  
Aidar F. Kamalov
Keyword(s):  
Thermal Stability ◽  
Aluminum Alloy ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Coarse Grained ◽  
Dynamic Precipitation ◽  
Ultrafine Grained ◽  
The Mean ◽  
Fatigue Endurance ◽  
Thermal Stability Of

The paper reports on microstructure, strength and fatigue of ultrafine-grained (UFG) samples of the Al-Cu-Mg-Si aluminum alloy processed by high pressure torsion (HPT) at various temperatures. Application of the HPT treatment led to strong grain refinement, as well as to a raise of the mean-root square strains and dynamic precipitation. In case of optimal HPT treatment the UFG samples have demonstrated the enhanced thermal stability, an increase in ultimate tensile strength in 2.5 times and enhancement in fatigue endurance limit by 20 % in comparison with coarse-grained alloy subjected to standard treatment. It is shown that the regime of the HPT treatment governs the volume fraction of precipitates and segregations, thereby affecting a grain size and thermal stability of ultrafine-grained structure.

Effect of ultrafine-grained microstructure on creep behaviour in 304L austenitic steel

2020 ◽  
Vol 785 ◽  
pp. 139383 ◽  
Author(s):  
Petr Kral ◽  
Jiri Dvorak ◽  
Vaclav Sklenicka ◽  
Zenji Horita ◽  
Yoichi Takizawa ◽  
...  
Keyword(s):  
Austenitic Steel ◽  
Creep Behaviour ◽  
Ultrafine Grained ◽  
Ultrafine Grained Microstructure

Structure and Fatigue Properties of the Mg Alloy AM60 Processed by ECAP

2008 ◽  
Vol 584-586 ◽  
pp. 803-808 ◽  
Author(s):  
Rinat K. Islamgaliev ◽  
Olya B. Kulyasova ◽  
Bernhard Mingler ◽  
Michael Zehetbauer ◽  
Alexander Minkow
Keyword(s):  
Grain Size ◽  
Endurance Limit ◽  
Volume Fraction ◽  
Coarse Grained ◽  
Fatigue Properties ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Mean Grain Size ◽  
Fatigue Endurance ◽  
Misorientation Angles

This paper reports on the microstructures and fatigue properties of ultrafine-grained (UFG) AM60 magnesium alloy processed by equal channel angular pressing (ECAP) at various temperatures. After ECAP processing, samples exhibited an increase in fatigue endurance limit, which correlates well with a decrease in grain size. In case of lowest ECAP temperature, the mean grain size is as small as 1 2m which leads to an increase in fatigue endurance limit by 70 % in comparison to coarse-grained alloy. The temperature of ECAP not only governs the grain size and misorientation angles of grain boundaries but also the volume fraction of precipitates, thus affecting the probability of twinning and grain growth after fatigue treatment.

Martensite Transformation of Ultrafine Grained Austenite in Fe-28.5at%Ni Alloy

2006 ◽  
Vol 503-504 ◽  
pp. 913-918 ◽  
Author(s):  
Hiromoto Kitahara ◽  
Nobuhiro Tsuji ◽  
Yoritoshi Minamino
Keyword(s):  
Martensite Transformation ◽  
Lamellar Spacing ◽  
Alloy Sheet ◽  
Coarse Grained ◽  
Boundary Structure ◽  
Ultrafine Grained ◽  
Ni Alloy ◽  
Mean Grain Size ◽  
The Mean ◽  
Lamellar Boundary

Martensite transformation of the ultrafine grained (UFG) austenite fabricated by the accumulative roll bonding (ARB) process was studied. The Fe-28.5at.%Ni alloy sheet was severely deformed in austenite state by the ARB process up to 5 cycles. The ARB processed sheet had the ultrafine lamellar boundary structure. The mean lamellar spacing was 230 nm in the 5 cycles specimen. The sheets ARB processed by various cycles were cooled down to 77 K to cause the martensite transformation. Martensite transformation starting (Ms) temperature decreased with increasing the number of the ARB process. The Ms temperature of the ultrafine lamellar austenite in the 5 cycles specimen was 225 K, which was lower than that (247 K) of the conventionally recrystallized specimen with mean grain size of 22 μm. The martensite having characteristic morphologies appeared from the UFG austenite, although the martensite transformed from the coarse-grained specimen showed typical plate (or lenticular) morphology. The strength of the nano-martensite transformed from the UFG austenite was about 1.5 times higher than that of the UFG austenite, and it reached to 970 MPa.

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.

scholarly journals Strength and Fracture Mechanism of an Ultrafine-Grained Austenitic Steel for Medical Applications

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7739
Author(s):  
Gennadiy V. Klevtsov ◽  
Ruslan Z. Valiev ◽  
Natal’ya A. Klevtsova ◽  
Maxim N. Tyurkov ◽  
Mikhail L. Linderov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Austenitic Steel ◽  
Cyclic Crack Resistance ◽  
Coarse Grained ◽  
Severe Plastic Deformation Processing ◽  
Medical Applications ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Coarse Grained State ◽  
Ultrafine Grained Steel

In this paper, we study the corrosion-resistant austenitic steel Fe-0.02C-18Cr-8Ni for medical applications. The microstructure and mechanical properties (tensile mechanical properties, torsional strength, impact toughness, and static and cyclic crack resistance) under different types of loading of the steel are investigated. The results are compared for the two states of the steel: the initial (coarse-grained) state and the ultrafine-grained state produced by severe plastic deformation processing via equal-channel angular pressing. It is demonstrated that the ultrafine-grained steel 0.08C-18Cr-9Ni has essentially better properties and is very promising for the manufacture of medical products for various applications that experience various static and cyclic loads during operation.

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.

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