EVALUATION OF HIGHT PURITY ALUMINIUM AFTER ASYMMETRIC ROLLING AT AMBIENT AND CRYOGENIC TEMPERATURES

<p class="AMSmaintitle"><span lang="EN-US">Ultrafine grained materials are capable of superplastic elongation at strain rates faster than those currently employed for commercial superplastic forming operations. However, such operations require the material in the form of thin sheets. Asymmetric rolling (ASR), as one of severe plastic deformation (SPD) methods, was used to make ultra-fined grain materials with enhanced performance. This work show effect of the deformation paths on micro-hardness and mechanical properties changing during asymmetric rolling of pure aluminium. In our case, the asymmetric condition was introduced by using different diameters with a ratio of upper and bottom roll 2,4. The thickness of samples was reduced about 20% - 40% at ambient temperature and at cryogenic temperature. Asymmetric rolling at cryogenic temperature (ASR-C) provides greater strength tensile properties than rolling at ambient temperature (ASR-A). </span></p>

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Thirty Years of Superplastic Ultrafine-Grained Materials: Examining the Legacy of Oscar Kaibyshev

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.385.3 ◽

2018 ◽

Vol 385 ◽

pp. 3-8 ◽

Cited By ~ 1

Author(s):

Terence G. Langdon

Keyword(s):

Plastic Deformation ◽

Superplastic Forming ◽

Superplastic Flow ◽

Scientific Curiosity ◽

Ultrafine Grained ◽

The World ◽

Ultrafine Grained Materials ◽

Academy Of Sciences ◽

Modern Status ◽

Zr Alloy

The occurrence of superplasticity may be traced to the classic work of Pearson conducted in the U.K. in 1934 when an elongation of 1950% was reported in a Pb-Sn eutectic alloy. Subsequently, much attention in Russia was devoted to this scientific curiosity and this led to the first book on superplasticity written by Prof. A.A. Presnyakov and published in 1964. Later, in 1985, Oscar Kaibyshev established in Ufa the Institute of Problems of Superplasticity of Metals of the Russian Academy of Sciences and this was, and remains to this day, the only institute in the world devoted exclusively to studies of the phenomenon of superplastic flow and the development through superplastic forming of complex-shaped parts. An important development occurred in 1988 with the publication of a classic report by Kaibyshev and co-workers describing the potential for achieving low temperature superplasticity in a metallic Al-Cu-Zr alloy that had been specially processed by severe plastic deformation (SPD) to produce a remarkably small grain size of only 300 nm. This report formed the basis for the later development of SPD processing as a major tool for the production of exceptional grain refinement and as a procedure for achieving large superplastic elongations that cannot be achieved using more conventional processing. This report describes this early work, the subsequent developments and the modern status of superplastic flow in ultrafine-grained metals.

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The mechanical properties of OFHC copper and CuCrZr alloys after asymmetric rolling at ambient and cryogenic temperatures

Open Engineering ◽

10.1515/eng-2018-0041 ◽

2018 ◽

Vol 8 (1) ◽

pp. 426-431

Author(s):

Róbert Kočiško ◽

Tibor Kvačkaj ◽

Andrea Kováčová ◽

Dušan Šimčák ◽

Róbert Bidulský ◽

...

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Ambient Temperature ◽

Shear Bands ◽

Ofhc Copper ◽

Cryogenic Temperatures ◽

Asymmetric Rolling ◽

Reduction Of Area ◽

Different Diameters ◽

Cryogenic Conditions

Abstract This work deals with comparing the mechanical properties of OFHC copper and CuCrZr alloys processed by asymmetric ambient rolling (ASaR) and asymmetric cryorolling (AScR). The conditions for asymmetrical rolling were ensured by different diameters of the main rolls. The thickness of samples was reduced about 20% - 70% at ambient temperature and at a temperature of liquid nitrogen. Mechanical properties such as yield strength, tensile strength, reduction of area and microhardness were determined for all rolled samples. Rolling at cryogenic temperatures provide about 50-60MPa more tensile strength for Cu and 60-80 MPa for CuCrZr alloys when rolling at ambient temperature. After AScR of CuCrZr alloys, a start of precipitation was shifted at the temperature of 434∘C and recrystallization was a part of the precipitation peak. According to the results, plastic deformation through shear bands is the dominant mechanism in materials with lower stacking fault energy (CuCrZr) treated under cryogenic conditions.

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Mechanical properties and microstructural evolution of ultrafine grained zircaloy-4 processed through multiaxial forging at cryogenic temperature

Transactions of Nonferrous Metals Society of China ◽

10.1016/s1003-6326(15)63835-3 ◽

2015 ◽

Vol 25 (7) ◽

pp. 2221-2229 ◽

Cited By ~ 15

Author(s):

D. FULORIA ◽

S. GOEL ◽

R. JAYAGANTHAN ◽

D. SRIVASTAVA ◽

G.K. DEY ◽

...

Keyword(s):

Mechanical Properties ◽

Microstructural Evolution ◽

Cryogenic Temperature ◽

Ultrafine Grained

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Superplastic Behavior in Ultrafine-Grained Materials Produced by Equal-Channel Angular Pressing

Materials Science Forum ◽

10.4028/www.scientific.net/msf.579.29 ◽

2008 ◽

Vol 579 ◽

pp. 29-40 ◽

Cited By ~ 3

Author(s):

Cheng Xu ◽

Megumi Kawasaki ◽

Roberto B. Figueiredo ◽

Zhi Chao Duan ◽

Terence G. Langdon

Keyword(s):

Equal Channel Angular Pressing ◽

High Strain ◽

Processing Method ◽

Strain Rates ◽

Bulk Materials ◽

Superplastic Behavior ◽

Angular Pressing ◽

Ultrafine Grained ◽

Ultrafine Grained Materials ◽

Aluminum And Magnesium Alloys

Equal-channel angular pressing (ECAP) is a convenient processing method for refining the grain size of bulk materials to the submicrometer level. Metallic alloys processed by ECAP often exhibit excellent superplastic characteristics including superplasticity at high strain rates. This paper summarizes recent experiments designed to evaluate the occurrence of superplasticity in representative aluminum and magnesium alloys and in the Zn-22% Al eutectoid alloy.

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Heterogeneous lamella structure unites ultrafine-grain strength with coarse-grain ductility

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1517193112 ◽

2015 ◽

Vol 112 (47) ◽

pp. 14501-14505 ◽

Cited By ~ 437

Author(s):

Xiaolei Wu ◽

Muxin Yang ◽

Fuping Yuan ◽

Guilin Wu ◽

Yujie Wei ◽

...

Keyword(s):

Large Scale ◽

Low Cost ◽

High Strength ◽

Back Stress ◽

Coarse Grained ◽

Ultrafine Grain ◽

Asymmetric Rolling ◽

Dislocation Hardening ◽

Ultrafine Grained ◽

Lamella Structure

Grain refinement can make conventional metals several times stronger, but this comes at dramatic loss of ductility. Here we report a heterogeneous lamella structure in Ti produced by asymmetric rolling and partial recrystallization that can produce an unprecedented property combination: as strong as ultrafine-grained metal and at the same time as ductile as conventional coarse-grained metal. It also has higher strain hardening than coarse-grained Ti, which was hitherto believed impossible. The heterogeneous lamella structure is characterized with soft micrograined lamellae embedded in hard ultrafine-grained lamella matrix. The unusual high strength is obtained with the assistance of high back stress developed from heterogeneous yielding, whereas the high ductility is attributed to back-stress hardening and dislocation hardening. The process discovered here is amenable to large-scale industrial production at low cost, and might be applicable to other metal systems.

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The New SPD Processing Trends to Fabricate Bulk Nanostructured Materials

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.114.7 ◽

2006 ◽

Vol 114 ◽

pp. 7-18 ◽

Cited By ~ 3

Author(s):

Ruslan Valiev

Keyword(s):

Plastic Deformation ◽

Severe Plastic Deformation ◽

Grain Refinement ◽

Nanostructured Materials ◽

Nanocrystalline Materials ◽

Commercial Production ◽

Materials Processing ◽

Ultrafine Grained ◽

Ultrafine Grained Materials ◽

Bulk Nanocrystalline

During the last decade severe plastic deformation (SPD) has become a widely known method of materials processing used for fabrication of ultrafine-grained materials with attractive properties. Nowadays SPD processing is rapidly developing and is on the verge of a transition from lab-scale research to commercial production. This paper focuses on several new trends in the development of SPD techniques for effective grain refinement, including those for commercial alloys and presents new SPD processing routes to produce bulk nanocrystalline materials.

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Improvement of formability of ultrafine-grained materials by post-SPD annealing

Materials Science and Engineering A ◽

10.1016/j.msea.2014.09.016 ◽

2014 ◽

Vol 619 ◽

pp. 119-128 ◽

Cited By ~ 20

Author(s):

O. Saray ◽

G. Purcek ◽

I. Karaman ◽

H.J. Maier

Keyword(s):

Ultrafine Grained ◽

Ultrafine Grained Materials

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The Processing of Ultrafine-Grained Materials Using High-Pressure Torsion

Materials Science Forum ◽

10.4028/www.scientific.net/msf.558-559.1283 ◽

2007 ◽

Vol 558-559 ◽

pp. 1283-1294 ◽

Cited By ~ 1

Author(s):

Cheng Xu ◽

Z. Horita ◽

Terence G. Langdon

Keyword(s):

Plastic Deformation ◽

Grain Size ◽

High Pressure ◽

High Pressure Torsion ◽

Metallic Materials ◽

Grain Sizes ◽

Ultrafine Grained ◽

Wide Range ◽

Ultrafine Grained Materials ◽

Thin Disks

It is now well-established that processing through the application of severe plastic deformation (SPD) leads to a significant reduction in the grain size of a wide range of metallic materials. This paper examines the fabrication of ultrafine-grained materials using high-pressure torsion (HPT) where this process is attractive because it leads to exceptional grain refinement with grain sizes that often lie in the nanometer or submicrometer ranges. Two aspects of HPT are examined. First, processing by HPT is usually confined to samples in the form of very thin disks but recent experiments demonstrate the potential for extending HPT also to bulk samples. Second, since the strains imposed in HPT vary with the distance from the center of the disk, it is important to examine the development of inhomogeneities in disk samples processed by HPT.

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