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Fracture and fracture toughness of nanopolycrystalline metals produced by severe plastic deformation.

Hohenwarter A, Pippan R - Philos Trans A Math Phys Eng Sci (2015)

Bottom Line: Nowadays, novel techniques provide access to much smaller grain sizes, where severe plastic deformation (SPD) is one of the most significant techniques.This opens the door to extend basic research in fracture mechanics to the nanocrystalline (NC) grain size regime.Here, an overview of recent results on the fracture behaviour of several different ultrafine-grained (d<1 μm) and NC (d<100 nm) metals and alloys covering examples of body- and face-centred cubic structures produced by SPD will be given.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Physics, Montanuniversität Leoben, Jahnstrasse 12, 8700 Leoben, Austria anton.hohenwarter@unileoben.ac.at.

ABSTRACT
The knowledge of the fracture of bulk metallic materials developed in the last 50 years is mostly based on materials having grain sizes, d, in the range of some micrometres up to several hundred micrometres regarding the possibilities of classical metallurgical methods. Nowadays, novel techniques provide access to much smaller grain sizes, where severe plastic deformation (SPD) is one of the most significant techniques. This opens the door to extend basic research in fracture mechanics to the nanocrystalline (NC) grain size regime. From the technological point of view, there is also the necessity to evaluate standard fracture mechanics data of these new materials, such as the fracture toughness, in order to allow their implementation in engineering applications. Here, an overview of recent results on the fracture behaviour of several different ultrafine-grained (d<1 μm) and NC (d<100 nm) metals and alloys covering examples of body- and face-centred cubic structures produced by SPD will be given.

No MeSH data available.


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(a) Example of UFG iron microstructures observed parallel to the principal viewing direction. (b) Principal specimen manufactured from the HPT discs and their orientations with respect to the introduced coordinate system.
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RSTA20140366F3: (a) Example of UFG iron microstructures observed parallel to the principal viewing direction. (b) Principal specimen manufactured from the HPT discs and their orientations with respect to the introduced coordinate system.

Mentions: Another important feature of HPT microstructures is the viewing direction onto the material, which has similar characteristics typical for extremely cold-rolled structures. The common coordinate system that will be used throughout the entire paper is shown in figure 3 in conjunction with an example of saturation microstructures of HPT processed iron inspected parallel to the major viewing directions. It can be clearly seen that in the radial viewing direction (RD) the microstructure exhibits an aligned and elongated shape, which is a result of the monotonically induced shear deformation. Also in the shear direction (SD), the grains show a certain elongated shape. In the axial direction (AD), the grains appear more or less equiaxed and look somewhat larger. Very often, this structure is also termed as a pancake-structure. This distinctive alignment of the structure into the SD, which is sometimes also named tangential direction (TD), will play an important role for the fracture toughness of various presented examples.Figure 3.


Fracture and fracture toughness of nanopolycrystalline metals produced by severe plastic deformation.

Hohenwarter A, Pippan R - Philos Trans A Math Phys Eng Sci (2015)

(a) Example of UFG iron microstructures observed parallel to the principal viewing direction. (b) Principal specimen manufactured from the HPT discs and their orientations with respect to the introduced coordinate system.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4342981&req=5

RSTA20140366F3: (a) Example of UFG iron microstructures observed parallel to the principal viewing direction. (b) Principal specimen manufactured from the HPT discs and their orientations with respect to the introduced coordinate system.
Mentions: Another important feature of HPT microstructures is the viewing direction onto the material, which has similar characteristics typical for extremely cold-rolled structures. The common coordinate system that will be used throughout the entire paper is shown in figure 3 in conjunction with an example of saturation microstructures of HPT processed iron inspected parallel to the major viewing directions. It can be clearly seen that in the radial viewing direction (RD) the microstructure exhibits an aligned and elongated shape, which is a result of the monotonically induced shear deformation. Also in the shear direction (SD), the grains show a certain elongated shape. In the axial direction (AD), the grains appear more or less equiaxed and look somewhat larger. Very often, this structure is also termed as a pancake-structure. This distinctive alignment of the structure into the SD, which is sometimes also named tangential direction (TD), will play an important role for the fracture toughness of various presented examples.Figure 3.

Bottom Line: Nowadays, novel techniques provide access to much smaller grain sizes, where severe plastic deformation (SPD) is one of the most significant techniques.This opens the door to extend basic research in fracture mechanics to the nanocrystalline (NC) grain size regime.Here, an overview of recent results on the fracture behaviour of several different ultrafine-grained (d<1 μm) and NC (d<100 nm) metals and alloys covering examples of body- and face-centred cubic structures produced by SPD will be given.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Physics, Montanuniversität Leoben, Jahnstrasse 12, 8700 Leoben, Austria anton.hohenwarter@unileoben.ac.at.

ABSTRACT
The knowledge of the fracture of bulk metallic materials developed in the last 50 years is mostly based on materials having grain sizes, d, in the range of some micrometres up to several hundred micrometres regarding the possibilities of classical metallurgical methods. Nowadays, novel techniques provide access to much smaller grain sizes, where severe plastic deformation (SPD) is one of the most significant techniques. This opens the door to extend basic research in fracture mechanics to the nanocrystalline (NC) grain size regime. From the technological point of view, there is also the necessity to evaluate standard fracture mechanics data of these new materials, such as the fracture toughness, in order to allow their implementation in engineering applications. Here, an overview of recent results on the fracture behaviour of several different ultrafine-grained (d<1 μm) and NC (d<100 nm) metals and alloys covering examples of body- and face-centred cubic structures produced by SPD will be given.

No MeSH data available.


Related in: MedlinePlus