A Study on Deformation Behaviour of Ultrafine Grained Materials

Ultrafine grained materials prepared by methods of severe plastic deformation appear to show good ductility for their high strength. To a large extent this ductility enhancement, for the given strength, is shown to correspond to the fracture ductility and not the uniform ductility at maximum stress. The improved fracture ductility is often due to the refinement or removal of the coarse defects that act as sites for failure nucleation. The low work hardening rate inherent to the very fine microstructures produced by severe plastic deformation essentially condemns such materials to very low uniform ductility. Stress relaxation occurring during unloading after processing, and changes of internal stresses during reloading for mechanical testing, appear to play a significant role in determining deformation behaviour near the onset of plastic flow, and this can affect the measured uniform strain.

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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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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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