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Number of results: 10
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Abstract

This paper presents the results obtained from the structural re.nement of selected metals and alloys produced by severe plasticdeformation processes. Large levels of deformations were produced using four methods, which di.ered in the character and dynamics of the loading, as well as in the intensity and homogeneity oft he plastic strain .eld. Qualitative and quantitative studies of the re.ned microstructure were carried out using stereological and computer image analytical methods. Microhardness and selected mechanical properties, such as strength and yield point, were also determined.

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Authors and Affiliations

K.J. Kurzydłowski
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Abstract

The development of the crystallographic texture in copper subjected to severe plastic deformation (SPD) by means of high pressure torsion (HPT) and equal-channel angular pressing (ECAP) was experimentally investigated and analyzed by means of computer modelling. It was demonstrated, that the texture developed in HPT and ECAP Cu is characterized by significant inhomogeneity. Therefore, the analysis focused on the study of the texture distribution and its inhomogeneity in sample space. The detailed texture analysis, based on the X-ray diffraction technique, led to important observations concerning the localization of the maximum texture gradient and the regularity of its changes related to the parameters of the applied deformation. The obtained results provided the basis for certain conclusions concerning complex texture changes in SPD Cu.

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Authors and Affiliations

I.V. Alexandrow
M.V. Zhilina
J.T. Bonarski
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Abstract

In the present paper, the effects of the subsequent extrusion after multi-pass equal-channel angular pressing (ECAP) process on the mechanical properties and microstructure of WE43 magnesium alloy are investigated. First, second and fourth passes ECAP followed by an extrusion process are applied on WE43 magnesium alloy to refine the microstructure and to improve the mechanical properties for biomedical applications. The results showed that among the ECAPed samples, the highest and lowest strength were obtained in the second and the first pass processed samples, respectively. The four passes processed sample showed the highest elongation to failure with moderate strength. The sample processed via first pass ECAP followed by extrusion exhibits an excellent combination of ductility and strength. The highest strength was obtained in the sample processed via the second pass ECAP followed by extrusion while the highest elongation was achieved in the sample processed via fourth pass ECAP followed by extrusion. Moreover, Vickers micro-indentation tests demonstrate that hardness is enhanced by an increase in the number of ECAP passes. Furthermore, a grain refinement process is presented for ECAP processing of WE43 alloy which shows a good agreement with microstructural investigations.

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Authors and Affiliations

A. Torkian
G. Faraji
M. Karimpour
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Abstract

The forming limit of AZ31 alloy, a representative Mg-Al-Zn-based wrought alloy, and the effect of severe plastic deformation (SPD) by examining the microstructure change caused by dynamic recrystallization led by high temperature and high dislocation density at 300℃ using a biaxial alternate forging (BAF) were investigated in this study. As a result of BAF test for AZ31 Mg alloy, significant cracks on the ends of workpieces occurred after 7 passes. The microstructure of as-extruded specimen showed the non-uniform distribution of the relatively coarse grains and the fine grains considered to be sub-grains. However, as the number of passes increases, the area of coarse grains gradually disappeared and the fine grains became more dominant in the microstructures. The result of tensile test for workpieces with each forging pass showed an increase in strength depending on pass number was shown with a slight increase of elongation. The Electron Backscatter Diffraction (EBSD) results exhibited that, the microstructure showed the presence of coarse grains and twins after only 1 pass, while the grains appeared to be significantly refined and uniformly distributed after 3 pass, at which the strength and elongation began to increase, simultaneously.
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Authors and Affiliations

Young-Chul Shin
1
ORCID: ORCID
Seong-Ho Ha
1
ORCID: ORCID
Abdul Wahid Shah
1
ORCID: ORCID

  1. Korea Institute of Industrial Technology (KITECH), Molding & Metal Forming R&D Department, 156 Gaetbeol-ro, Yeonsu-gu, Incheon 21999, Republic of Korea
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Abstract

This study was undertaken to investigate the effect of severe plastic deformation (SPD) by extrusion combined with reversible torsion (KoBo) method on microstructure and mechanical properties of Al-5Cu and Al-25Cu alloys. The extrusion combined with reversible torsion was carried out using reduction coefficient of λ = 30 and λ = 98. In this work, the microstructure was characterized by light microscopy (LM), scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM). Compression test and tensile test were performed for deformed alloys. The binary Al-5Cu and Al-25Cu alloys consist of the face cantered cubic (FCC) α phase in the form of dendrites and tetragonal (C16) θ-Al2Cu intermetallic phase observed in interdentritic regions. The increase of Cu content leads to increase of interdentritic regions. The microstructure of the alloys is refined after applying KoB deformation with λ = 30 and λ = 98. Ultimate Tensile Strength (UTS) of Al-5Cu alloy after KoBo deformation with λ = 30 and λ = 98 reached about 200 MPa. UTS for samples of Al-25Cu with λ = 30 and λ = 98 increased compared to Al-5Cu alloy and exceed 320 MPa and 270 MPa respectively. All samples showed increase of plasticity with increase of reduction coefficient. Independently of reduction coefficient, the compressive strain of Al-5Cu alloys is about 60%. The Al-25Cu alloy with λ = 98 showed the value of compressive strain exceed 60%, although for this same alloy but with λ = 30, the compressive strain is only 35%.

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Authors and Affiliations

K. Rodak
A. Brzezińska
J. Sobota
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Abstract

The paper gives an introduction to nanostructuring techniques used for industrial fabrication of bulk nanocrystalline metals – basic

materials utilized in shaping nanoscale structures. Nanostructured metals, called nanometals, can be produced by severe plastic deformation (SPD). We give an expert coverage of current achievements in all important SPD methods and present future industry developments and research directions including both batch and continuous processes. In the laboratories of both WUT and UOS we have developed industry standard equipment and machinery for nanometals processing. Utilizing the latest examples from our research, we provide a concise introduction to the field of mass production of nanometals for nanotechnology.

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Authors and Affiliations

L. Olejnik
A. Rosochowski
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Abstract

The samples of the CuCr0.6 alloy in the solution treated and additionally in aging states were severely plastically deformed by compression with oscillatory torsion (COT) method to produce ultrafine – grained structure. The samples were processed by using process parameters as: frequency of torsion (f = 1.6 Hz), compression speed (v = 0.04 mm/s), angle torsion (α = ±6°), height reduction (Δh = 7 mm). The total effective strain was εft = 40. The microstructure has been analyzed by scanning transmission electron microscope (STEM) Hitachi HD-2300A equipped with a cold field emission gun at an accelerating voltage of 200 kV. The quantitative microstructure investigations as disorientation angles were performed using a FEI INSPECT F scanning electron microscope (SEM) equipped with a cold field emission gun and a electron backscattering diffraction (EBSD) detector. The mechanical properties were determined using MST QTest/10 machine equipped with digital image correlation (DIC). The COT processed alloy previously aged at 500°C per 2h shows high mechanical strength, ultimate tensile strength UTS: 521 MPa and yield tensile strength YS: 488 MP attributed to the high density of coherent precipitates and ultrafine grained structure.

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Authors and Affiliations

A. Urbańczyk-Gucwa
A. Brzezińska
K. Rodak
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Abstract

Oxide-dispersion-strengthened high-entropy alloys were produced by hot-pressing a ball-milled mixture of Y2O3 and atomized CoCrFeMnNi powder. The effect of milling duration on grain size reduction, oxide formation behavior, and the resulting mechanical properties of the alloys was studied. Both the alloy powder size and Y2O3 particle size decreased with milling time. Moreover, the alloy powder experienced severe plastic deformation, dramatically generating crystalline defects. As a result, the grain size was reduced to ~16.746 nm and in-situ second phases (e.g., MnO2 and σ phase) were formed at the defects. This increased the hardness of the alloys up to a certain level, although excessive amounts of in-situ second phases had the reverse effect.
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Bibliography

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Authors and Affiliations

Yongwook Song
1
ORCID: ORCID
Daeyoung Kim
1
ORCID: ORCID
Seungjin Nam
1
ORCID: ORCID
Kee-Ahn Lee
2
ORCID: ORCID
Hyunjoo Choi
1
ORCID: ORCID

  1. Kookmin University, School of Materials Science and Engineering, Seoul, Republic of Korea
  2. Inha University, Department of Materials Science and Engineering, Incheon 22212, Republic of Korea
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Abstract

Microstructure and texture of the CuCr0.6 alloy processed by rolling with cyclic movement of rolls (RCMR) at room temperature were investigated. The RCMR processing was applied for the samples in different initial conditions in the solid solution followed by quenching into iced water at 1000oC for 3 h and in aging treatment conditions performed at 500oC for 2 h and at 700oC for 24 h. Application of the solution and aging processes prior to RCMR deformation results in the partial dissolution of Cr particles into the Cu matrix and precipitation of the second phase particles. RCMR processing with value of the total effective strain (εft) of 5 was introduced to the material. It was found that the RCMR method is effective in texture weakening. The obtained results revealed that there is a large similarity in texture orientations after RCMR processing independently of heat treatment conditions. Cyclic character of deformation leads to an incomplete transition of LAB to HAB.

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Authors and Affiliations

A. Urbańczyk-Gucwa
A. Brzezińska
B. Adamczyk-Cieślak
ORCID: ORCID
K. Rodak
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Abstract

Two strength-age hardening aluminum-lithium alloys: Al-2.3wt%Li and Al-2.2wt%Li-0.1wt%Zr in two different heat treatment conditions: solution state (S) and additionally in aging state (A) were severely plastically deformed by rolling with cyclic movement of rolls (RCMR) method to produce ultrafine – grained structure. Two thermo-mechanical treatments were used: (S+A+RCMR) and (S+RCMR+A+RCMR). To investigate the combined effect of plastic deformation and heat treatment, tensile tests were performed. Microstructural observations were undertaken using scanning transmission electron microscopy (STEM), and scanning transmission electron microscopy (SEM) equipped with electron backscattering diffraction detector (EBSD). Based on the obtained results, it can be deduced that maximum mechanical properties as: yield strength (YS) and ultimate tensile strength (UTS) could be achieved when the microstructure of alloys is in (S+A+RCMR) state. For samples in (S+RCMR+A+RCMR) state, ductility is higher than for (S+A+RCMR) state. The microstructural results shows that the favourable conditions for decreasing grain size of alloys is (S+A+RCMR) state. Additionally, in this state is much greater dislocation density than for (S+RCMR+A+RCMR) state. The microstructure of alloys in (S+RCMR+A+RCMR) state is characterized by grains/subgrains with higher average diameter and with higher misorientation angles compared with (S+A+RCMR) state.

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Authors and Affiliations

A. Brzezińska
A. Urbańczyk-Gucwa
R. Molak
K. Rodak

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