Developing the Technique of Severe Plastic Deformation Processing through High-Pressure Torsion

2010 ◽  
Vol 667-669 ◽  
pp. 397-402 ◽  
Author(s):  
Megumi Kawasaki ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
High Pressure Torsion ◽  
Severe Plastic Deformation Processing ◽  
Average Grain Size ◽  
High Purity Aluminum ◽  
Sample Characteristics ◽  
Nanoscale Range

The processing of metals through the application of severe plastic deformation provides the potential for achieving exceptional grain refinement in bulk solids. Several SPD methods are now available but processing by high-pressure torsion (HPT) has attracted much attention over the last five years. Numerous reports are now available describing the application of HPT to a range of pure metals and simple alloys and excellent grain refinement were achieved using this process with the average grain size often reduced to the nanoscale range. However, in order to make this technique more practical, the nature of the sample characteristics immediately after conventional HPT must be considered in order to understand the fundamental principles of HPT processing. This report examines the procedure with special emphasis on the evolution in hardness homogeneity in both high-purity aluminum and a Zn-22% Al eutectoid alloy processed by HPT.

Effect of SPD Processing Technique on Grain Refinement and Properties of an Austenitic Stainless Steel

2016 ◽  
Vol 879 ◽  
pp. 1957-1962 ◽  
Author(s):  
Marina Tikhonova ◽  
Iaroslava Shakhova ◽  
Rustam Kaibyshev ◽  
Andrey Belyakov
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Stainless Steel ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
High Pressure Torsion ◽  
Processing Technique ◽  
Multidirectional Forging ◽  
Average Grain Size ◽  
Nanocrystalline Structures

The formation of nanocrystalline structures and mechanical properties were studied in a nitrogen-bearing 304-type stainless steel subjected to severe plastic deformation (SPD). The steel samples were processed at ambient temperature using three different methods, i.e., caliber rolling, multidirectional forging and high pressure torsion. All these techniques resulted in pronounced grain refinement. The microstructures consisting of austenite/ferrite crystallites with transverse dimensions of 50 and 30 nm evolved in the rolled and forged samples, respectively. The austenite fractions comprised approximately 0.4. In contrast, the microstructure consisted mainly of austenite with an average grain size of about 25 nm evolved after high pressure torsion. All samples of the stainless steel subjected to severe plastic deformation demonstrated significant strengthening. The ultimate tensile strengths of 2065 MPa and 1950 MPa, were obtained after rolling and high pressure torsion, respectively. The ultimate tensile strength of samples subjected to multidirectional forging was 1540 MPa.

GRAIN REFINEMENT AND MICROSTRUCTURE EVOLUTION IN ALUMINUM A2618 ALLOY BY HIGH-PRESSURE TORSION

2016 ◽  
Vol 78 (6-9) ◽  
Author(s):  
Intan Fadhlina Mohamed ◽  
Seungwon Lee ◽  
Kaveh Edalati ◽  
Zenji Horita ◽  
Shahrum Abdullah ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Grain Refinement ◽  
Room Temperature ◽  
Rotation Speed ◽  
High Pressure Torsion ◽  
Applied Pressure ◽  
Saturation Level ◽  
Microstructural Refinement ◽  
Average Grain Size

This work presents a study related to the grain refinement of an aluminum A2618 alloy achieved by High-Pressure Torsion (HPT) known as a process of Severe Plastic Deformation (SPD). The HPT is conducted on disks of the alloy under an applied pressure of 6 GPa for 1 and 5 turns with a rotation speed of 1 rpm at room temperature. The HPT processing leads to microstructural refinement with an average grain size of ~250 nm at a saturation level after 5 turns. Gradual increases in hardness are observed from the beginning of straining up to a saturation level. This study thus suggests that hardening due to grain refinement is attained by the HPT processing of the A2618 alloy at room temperature.

scholarly journals Microstructure evolution of Al-7wt%Si-2wt%Fe alloy processed by high-pressure torsion

2018 ◽  
Vol 192 ◽  
pp. 02068
Author(s):  
Jittraporn Wongsa-Ngam ◽  
Chakkrist Phongphisutthinan ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Microstructure Evolution ◽  
High Pressure Torsion ◽  
Intermetallic Phase ◽  
Optical Microscope ◽  
Severe Plastic Deformation Processing ◽  
Silicon Based ◽  
Aluminum Silicon

The microstructure evolution of an aluminum silicon-based alloy after severe plastic deformation processing was examined. An aluminum silicon-based alloy; Al-7wt%Si-2wt%Fe, was processed by the severe plastic deformation technique called high-pressure torsion at room temperature under a high pressure of 6.0 GPa and rotational speed of 1.0 rpm with numbers of revolution up to 5 turns. Microstructure evolution, especially intermetallic phase, was observed using an optical microscope and a scanning electron microscope (SEM). The effects of high-pressure torsion on the Fe intermetallic compounds in Al-Si alloy were investigated. It was found that the intermetallic particles decreased in size with increasing imposed strains.

Analysis of the Fundamental Mechanisms and Efficiency of the Deformation Methods of Nanostructuring

2008 ◽  
Vol 584-586 ◽  
pp. 29-34 ◽  
Author(s):  
Radik R. Mulyukov ◽  
Ayrat A. Nazarov ◽  
Renat M. Imayev
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Pressure ◽  
High Temperature ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
Efficient Method ◽  
High Pressure Torsion ◽  
Angular Pressing

Deformation methods of nanostructuring (DMNs) of materials are proposed to classify into severe plastic deformation (SPD) and mild plastic deformation (MPD) methods according to fundamentally different low- and high-temperature grain refinement mechanisms they exploit. A general analysis of the fundamentals and nanostructuring efficiency of three most developed DMNs, high pressure torsion (HPT), equal-channel angular pressing (ECAP), and multiple isothermal forging (MIF) is done with a particular attention to ECAP and MIF. It is demonstrated that MIF is the most efficient method of DMNs allowing one to obtain the bulkiest nanostructured samples with enhanced mechanical properties.

Severe Plastic Deformation under High Pressure for Production of Superplastic Materials

2016 ◽  
Vol 838-839 ◽  
pp. 287-293 ◽  
Author(s):  
Zenji Horita
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
High Pressure Torsion ◽  
High Strength ◽  
Al Alloys ◽  
Strain Rates ◽  
Ti Alloys

Grain refinement is an important prerequisite for advent of superplasticity. In particular, as the grain size is smaller, the superplasticity appears at higher strain rates and lower temperatures. Severe plastic deformation (SPD) is a useful process for achieving significant grain refinement. This presentation shows that applicability of the SPD process is enhanced when it is operated under high pressure through high-pressure torsion (HPT) and high-pressure sliding (HPS). It is demonstrated that commercially available conventional alloys but less ductile alloys such as Mg alloys, age-hardenable high-strength Al alloys (A2024, A7075) and Ti alloys become superplastic after processing by HPT or HPS.

scholarly journals The Effect of the In-Situ Heat Treatment on the Martensitic Transformation and Specific Properties of the Fe-Mn-Si-Cr Shape Memory Alloys Processed by HSHPT Severe Plastic Deformation

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4621
Author(s):  
Carmela Gurau ◽  
Gheorghe Gurau ◽  
Felicia Tolea ◽  
Bogdan Popescu ◽  
Mihaela Banu ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
High Speed ◽  
High Pressure Torsion ◽  
Electron Interaction ◽  
Sudden Increase ◽  
Neel Temperature ◽  
Néel Temperature

This work focuses on the temperature evolution of the martensitic phase ε (hexagonal close packed) induced by the severe plastic deformation via High Speed High Pressure Torsion method in Fe57Mn27Si11Cr5 (at %) alloy. The iron rich alloy crystalline structure, magnetic and transport properties were investigated on samples subjected to room temperature High Speed High Pressure Torsion incorporating 1.86 degree of deformation and also hot-compression. Thermo-resistivity as well as thermomagnetic measurements indicate an antiferromagnetic behavior with the Néel temperature (TN) around 244 K, directly related to the austenitic γ-phase. The sudden increase of the resistivity on cooling below the Néel temperature can be explained by an increased phonon-electron interaction. In-situ magnetic and electric transport measurements up to 900 K are equivalent to thermal treatments and lead to the appearance of the bcc-ferrite-like type phase, to the detriment of the ε(hcp) martensite and the γ (fcc) austenite phases.

Role of Strain Gradient and Dynamic Transformation on the Formation of Nanocrystalline Structure Produced by Severe Plastic Deformation

2007 ◽  
Vol 539-543 ◽  
pp. 2787-2792 ◽  
Author(s):  
Minoru Umemoto ◽  
Yoshikazu Todaka ◽  
Jin Guo Li ◽  
Koichi Tsuchiya
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Strain Gradient ◽  
High Pressure Torsion ◽  
Large Strain ◽  
Nanocrystalline Structure ◽  
Angular Pressing ◽  
Dynamic Transformation ◽  
Fine Grained Structure

Formation of nanocrystalline structure by severe plastic deformation has studied extensively. Although ultra fine grained structure (grain size larger than 100 nm) had been obtained in many processes such as heavy cold rolling, equal channel angular pressing (ECAP) or accumulative roll bonding (ARB), the formation of nano grained structure (< 100 nm) is limited to processes such as ball milling, shot peening or drilling. In the present study, high pressure torsion (HPT) deformation and drilling were carried out to understand the conditions necessary to obtain nano grained structure in steels. The results of HPT experiments in pure Fe showed that HPT has superior ability of strengthening and grain refinement probably due to a strain gradient but the saturation of grain refinement occurs before reaching nano grained structure. Drilling experiments in high carbon martensitic steel revelaed that nano grained ferrite forms at the drilled hole surface only when the transformation from ferrite to austenite takes place during drilling. Considering various other processes by which nano grained ferrite was produced, it is proposed that heavy strains with large strain gradients together with dynamic transformation are necessary to reach nano grained ferrite structure.

Structure and Properties of Grain Boundaries in Submicrocrystalline W Obtained by Severe Plastic Deformation

2009 ◽  
Vol 283-286 ◽  
pp. 629-638 ◽  
Author(s):  
Vladimir V. Popov ◽  
Ruslan Valiev ◽  
E.N. Popova ◽  
A.V. Sergeev ◽  
A.V. Stolbovsky ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Grain Boundaries ◽  
High Pressure Torsion ◽  
Submicrocrystalline Structure ◽  
Emission Mössbauer Spectroscopy ◽  
Structure And Properties ◽  
Initial State

Submicrocrystalline structure of W obtained by severe plastic deformation (SPD) by high pressure torsion (5 revolutions of anvils at 4000C) and its thermal stability have been examined by TEM. Grain boundaries of submicrocrystalline W have been studied by the method of the emission Mössbauer spectroscopy in the initial state and after annealing at 400-6000С.

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