The Effect of Severe Plastic Deformation Processing on Creep Properties of Metallic Materials

2015 ◽  
Vol 651-653 ◽  
pp. 639-644
Author(s):  
Jiri Dvorak ◽  
Petr Král ◽  
Vaclav Sklenička ◽  
Milan Svoboda ◽  
Marie Kvapilová
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Electron Backscatter Diffraction ◽  
Bulk Material ◽  
Creep Behaviour ◽  
Tensile Creep ◽  
Severe Plastic Deformation Processing ◽  
Processing Route ◽  
Creep Tests ◽  
Creep Properties

Processing by severe plastic deformation (SPD) may be defined as such metals forming procedure in which a very high strain is imposed on a bulk material. This paper investigates the effect of different equal channel angular pressing (ECAP) routes and number of ECAP passes on resulting microstructure, mechanical properties and creep behaviour of selected materials. The distinction between various ECAP routes (A, B and C) and the difference in number of ECAP passes applied may lead to variations both in the macroscopic distortions of the individual grains and in the capability to develop a reasonably homogeneous and equiaxed ultrafine-grained microstructure. Experimental materials were processed by ECAP at room temperature using a die with an internal angle of 90° between the two parts of the channel. The ECAP pressing was performed by different routes up to 12 ECAP passes. Tensile creep tests were conducted at temperatures 473 - 673 K and at different applied stresses on ECAP materials and, for comparison purposes, on their unpressed states. Microstructure of samples was characterized by scanning electron microscope (SEM) equipped with the electron backscatter diffraction (EBSD) unit. In conclusion, the ECAP processing route and number of applied ECAP passes could play an important role in creep behaviour and their effect may be different for particular materials. The highest differences in processing routes were revealed for materials especially at lower number of ECAP passes. However, a little apparent dependence of the creep properties was observed during subsequent pressing.

The Creep Behaviour of Extruded Mg-5Li-3Al-1.5Zn-2RE Alloy

2011 ◽  
Vol 213 ◽  
pp. 492-496 ◽  
Author(s):  
Ting Qu Li ◽  
Yong Bing Liu ◽  
Zhan Yi Cao ◽  
Li Ren Cheng ◽  
Dong Mei Jiang
Keyword(s):  
Electron Microscopy ◽  
Creep Behaviour ◽  
Microstructural Analysis ◽  
Extrusion Process ◽  
Intermetallic Phases ◽  
Tensile Creep ◽  
Dislocation Creep ◽  
Creep Tests ◽  
Creep Properties ◽  
Transmission Electron

The Mg-5Li-3Al-1.5Zn-2RE (LaPrCe) alloy was prepared by hot-chamber extrusion process after casting. The alloy consists of α-Mg solid solution and intermetallic phases (Al11RE3 phase and Al2RE phase). The microstructural analysis of the alloy reveals the correlation between microstructure and creep properties. The stress exponent of n varies from 4.25 to 6.23, and the activation energy varies from 104 to 134 kJ/mol. There is a transition between dislocations climb dominated creep mechanism and dislocation creep controlled by non-basal planes slip. Tensile creep tests were combined with detailed transmission electron microscopy in order to characterize the Al11RE3 phase, which had thermal stability at 448K during the creep test. The dislocations pinned and cross-slip dislocations were observed.

Microstructure Stability and Creep Behaviour of a Cu-0.2wt.%Zr Alloy Processed by Equal-Channel Angular Pressing

2010 ◽  
Vol 667-669 ◽  
pp. 821-826 ◽  
Author(s):  
Jiří Dvořák ◽  
Petr Král ◽  
Marie Kvapilová ◽  
Milan Svoboda ◽  
Vàclav Sklenička
Keyword(s):  
Electron Microscopy ◽  
Equal Channel Angular Pressing ◽  
Creep Behaviour ◽  
Tensile Creep ◽  
Creep Tests ◽  
Creep Properties ◽  
Angular Pressing ◽  
Microstructure Stability ◽  
Transmission Electron ◽  
Zr Alloy

A dispersion-strengthened Cu-0.2 wt.% Zr alloy was subjected to equal-channel angular pressing (ECAP) at room temperature for up to 12 passes through route BC using a die having a channel angle of 90°. The microstructural investigations were performed using both transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Tensile creep tests were conducted at temperature 673 K and at the applied stress in the range from 80 to 180 MPa. The migration of boundaries and subsequent grain growth were restricted by Cu9Zr2 precipitates. The study was performed in order to evaluate the effects of severe plastic deformation and precipitation on creep behaviour and microstructure of the pressed alloy. It was found that creep behaviour is strongly dependent on number of ECAP passes. The pressed alloy after up to 4 ECAP passes exhibited a considerable improvement in creep properties in comparison with the unpressed alloy.

scholarly journals The Effect of Predeformation on Creep Strength of 9% Cr Steel

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5330
Author(s):  
Petr Král ◽  
Jiří Dvořák ◽  
Wolfgang Blum ◽  
Václav Sklenička ◽  
Zenji Horita ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Grain Boundaries ◽  
High Pressure Torsion ◽  
Tensile Creep ◽  
Initial Stresses ◽  
High Angle ◽  
Creep Tests ◽  
P92 Steel

Martensitic creep-resistant P92 steel was deformed by different methods of severe plastic deformation such as rotation swaging, high-pressure sliding, and high-pressure torsion at room temperature. These methods imposed significantly different equivalent plastic strains of about 1–30. It was found that rotation swaging led to formation of heterogeneous microstructures with elongated grains where low-angle grain boundaries predominated. Other methods led to formation of ultrafine-grained (UFG) microstructures with high frequency of high-angle grain boundaries. Constant load tensile creep tests at 873 K and initial stresses in the range of 50 to 300 MPa revealed that the specimens processed by rotation swaging exhibited one order of magnitude lower minimum creep rate compared to standard P92 steel. By contrast, UFG P92 steel is significantly softer than standard P92 steel, but differences in their strengths decrease with increasing stress. Microstructural results suggest that creep behavior of P92 steel processed by severe plastic deformation is influenced by the frequency of high-angle grain boundaries and grain coarsening during creep.

Development of Textured Coated Superconductor Substrate Tapes by Severe Plastic Deformation Processing

2010 ◽  
Vol 667-669 ◽  
pp. 1189-1194
Author(s):  
Pinaki Prasad Bhattacharjee ◽  
Nobuhiro Tsuji
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Purity ◽  
Cube Texture ◽  
Starting Material ◽  
Coarse Grained ◽  
Severe Plastic Deformation Processing ◽  
Processing Route ◽  
Fine Grained ◽  
Average Grain Size

An attempt has been made to fabricate highly cube textured ({001}<100>) polycrystalline nickel substrate tapes for coated superconductor applications using severe plastic deformation route. For this purpose high purity Ni (~99.97%) plates with widely different average grain size (28 µm or fine grained starting material and 650 µm or coarse grained starting material, respectively) are severely deformed by Accumulative Roll Bonding (ARB) up to an equivalent strain level of (εeq = 6.4) and annealed at various temperatures between 300° to 800°C for one hour. Upon annealing at different temperatures, the fine grained starting material developed a much stronger cube texture than the coarse grained starting material. By suitable annealing treatment near 100% cube textured tape could be obtained in the SPD processed fine grained nickel tapes having a predominantly low angle boundary network. The observed difference in the strength of cube texture in the two materials could be explained based on the oriented nucleation mechanism of formation of cube texture. The present results indicate that SPD processing route such as ARB is very effective in fabricating high purity Ni or Ni alloys intended for coated superconductor substrate applications.

scholarly journals Polycrystal Simulation of Texture-Induced Grain Coarsening during Severe Plastic Deformation

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5834
Author(s):  
Chi Zhang ◽  
Laszlo S. Toth
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Electron Backscatter Diffraction ◽  
Texture Evolution ◽  
Face Centered Cubic ◽  
Shear Texture ◽  
Grain Coarsening ◽  
Random Texture ◽  
Polycrystal Plasticity ◽  
Grain Fragmentation

During severe plastic deformation (SPD), there is usually extended grain fragmentation, associated with the formation of a crystallographic texture. The effect of texture evolution is, however, coarsening in grain size, as neighbor grains might coalesce into one grain by approaching the same ideal orientation. This work investigates the texture-induced grain coarsening effect in face-centered cubic polycrystals during simple shear, in 3D topology. The 3D polycrystal aggregate was constructed using a cellular automaton model with periodic boundary conditions. The grains constituting the polycrystal were assigned to orientations, which were updated using the Taylor polycrystal plasticity approach. At the end of plastic straining, a grain detection procedure (similar to the one in electron backscatter diffraction, but in 3D) was applied to detect if the orientation difference between neighboring grains decreased below a small critical value (5°). Three types of initial textures were considered in the simulations: shear texture, random texture, and cube-type texture. The most affected case was the further shearing of an initially already shear texture: nearly 40% of the initial volume was concerned by the coalescence effect at a shear strain of 4. The coarsening was less in the initial random texture (~30%) and the smallest in the cube-type texture (~20%). The number of neighboring grains coalescing into one grain went up to 12. It is concluded that the texture-induced coarsening effect in SPD processing cannot be ignored and should be taken into account in the grain fragmentation process.

The Experimental Determination of the Friction Stress between the Semi-Product and the Active Plate at the Multiaxial Forging of Copper

2014 ◽  
Vol 803 ◽  
pp. 216-221 ◽  
Author(s):  
Alin Marian Cazac ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Cristian Predescu ◽  
Andrei Victor Sandhu ◽  
Costică Bejinariu
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Friction Force ◽  
Friction Stress ◽  
Severe Plastic Deformation Processing ◽  
Total Force ◽  
Finished Part ◽  
Closed Die Forging ◽  
Deformation Force

The paper aims the determination of the friction force by means of external friction stress, at the severe plastic deformation processing using cyclic closed-die forging method. It is known that the total force used at the severe plastic deformation by the method of multiaxial forging is being composed by the deformation force itself and the friction force between the semi-product and the deformation tools. Once the friction stresses known, for a certain material, one can determine the friction force corresponding for a given deformation of a semi-product of a particular shape and sizes. By means of the flowing curve of the semi-product material one can determine the deformation force, which together with the friction force give the total necessary force for a deformation and so one can choose the necessary equipment for the processing of the material by severe plastic deformation. For this purpose it has been severely plastic deformed by the method of multiaxial forging, a semi-product having the sizes 10x10x20 mm, the finished part having the same sizes and shape. It has been measured the deformation force and the extraction force of the finished part from the cavity of the active plate, the late being used for the determination of the friction stress between the semi-product and the active plate.

Effect of Processing Route on Microstructure and Mechanical Behaviour of Ultrafine Grained Metals Processed by Severe Plastic Deformation

2005 ◽  
Vol 482 ◽  
pp. 83-88 ◽  
Author(s):  
Vàclav Sklenička ◽  
Jiří Dvořák ◽  
Milan Svoboda ◽  
Petr Král ◽  
B. Vlach
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Mechanical Behavior ◽  
Mechanical Behaviour ◽  
Melt Spinning ◽  
Processing Route ◽  
Ultrafine Grained ◽  
Water Atomization

Aluminum-based alloys containing quasicrystalline particles of 50 – 600 nm in diameter as a reinforcing phase were produced in the form of powder or ribbons by water atomization or melt spinning techniques, respectively. Rods were compacted from powders and some ribbons by severe plastic deformation without sintering. Structure and mechanical behavior of alloys are discussed.

Microstructure and Creep Properties of AJ62 and AE44 Die-Casting Magnesium Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 1546-1551 ◽  
Author(s):  
Andrzej Kiełbus ◽  
Tomasz Rzychoń
Keyword(s):  
Magnesium Alloys ◽  
Creep Resistance ◽  
Cell Structure ◽  
Creep Behaviour ◽  
Die Casting ◽  
Tensile Creep ◽  
Creep Properties ◽  
Die Cast ◽  
Subgrain Formation ◽  
Good Creep Resistance

Microstructure and tensile creep behaviour of the die-cast AE44 and AJ62 magnesium alloys has been studied at temperatures between 175°C and 200°C and at stresses in the range from 60 to 75 MPa. At the 175°C the AJ62 and AE44 alloys exhibit good creep resistance after 120h creep deformation. At 200°C the AE44 alloy shows still good creep resistance, whereas in the case of AJ62 alloy the rapid decreasing of creep resistance has been observed. TEM observations reveal dislocations cell structure in AE44 alloy after creep test. In AJ62 alloy subgrain formation and decreasing the dislocation density have been observed.

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