castagna_friction and wear of materials notes _ beilby layer scamans 2010_unknown_2010

Taylor Castagna MANE 6960 – Friction and Wear of Materials Notes – Beilby Layer Scamans 2010 I. Abstract • Examined Beilby layers on all types of aluminum surfaces subjected to high shear processing (rolling, grinding, and machining.) The layers are microcrystalline rather than amorphous. They strongly influence properties like corrosion resistance and reflectance. • Able to directly image Beilby layers using SEM and TEM II. Introduction • Multiple theories on the formation of the layer – plastic strain, local melting. • Rigney theorized that the wear surfaces were formed from a combination of fragments from both wear surfaces that were mixed together in a process akin to mechanical alloying. • The purpose of this paper is to put the results of studies that showed the Beilby layer in hot and then cold rolled aluminum sheet is between 0.4 micro and 0.8 micro meters. III. Experimental • Scanning electron microscope and a transmission electron microscope were used. IV. Results and Discussion • Hot rolled surface i. Little to no systematic study performed on the microstructural evolution of the hot rolled surface of commercial aluminum processing ii. Sheffield found high aspect ratio rolling with rough roll surfaces resulted in rapid removal of material from the slab surface by adhesion and abrasion resulting in the scalloped surface and a subsurface with fine grains and oxides. • Cold rolled surface i. Carried out on samples that have been hot rolled and annealed and then progressively cold rolled to final gauge sheet. This means the analysis is performed on cold rolling of layers formed during the hot forming process that are then modified by annealing. ii. Beilby layers after hot rolling and the early stages of cold rolling are thinned and disappear during rolling ops where there is essentially no shear between the strip and the work roll. • Mechanically ground and polished surfaces i. Much less thermally stable than those produces by hot rolling. The layers can usually be removed by annealing. • Machined Surfaces i. Shows a susceptibility to corrosion after ageing V. Conclusions • Hot rolling and cold rolling results in the formation of thin ultrafine grained surface layers that modify both corrosion performance and surface appearance.

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Taylor Castagna

MANE 6960 Friction and Wear of Materials

Notes Beilby Layer Scamans 2010

I. Abstract

Examined Beilby layers on all types of aluminum surfaces subjected to high shear processing (rolling, grinding, and machining.) The layers are microcrystalline rather than

amorphous. They strongly influence properties like corrosion resistance and reflectance.

Able to directly image Beilby layers using SEM and TEM II. Introduction

Multiple theories on the formation of the layer plastic strain, local melting. Rigney theorized that the wear surfaces were formed from a combination of fragments

from both wear surfaces that were mixed together in a process akin to mechanical

alloying.

The purpose of this paper is to put the results of studies that showed the Beilby layer in hot and then cold rolled aluminum sheet is between 0.4 micro and 0.8 micro meters.

III. Experimental

Scanning electron microscope and a transmission electron microscope were used. IV. Results and Discussion

Hot rolled surface i. Little to no systematic study performed on the microstructural evolution of the

hot rolled surface of commercial aluminum processing

ii. Sheffield found high aspect ratio rolling with rough roll surfaces resulted in rapid removal of material from the slab surface by adhesion and abrasion resulting in

the scalloped surface and a subsurface with fine grains and oxides.

Cold rolled surface i. Carried out on samples that have been hot rolled and annealed and then

progressively cold rolled to final gauge sheet. This means the analysis is

performed on cold rolling of layers formed during the hot forming process that

are then modified by annealing.

ii. Beilby layers after hot rolling and the early stages of cold rolling are thinned and disappear during rolling ops where there is essentially no shear between the

strip and the work roll.

Mechanically ground and polished surfaces i. Much less thermally stable than those produces by hot rolling. The layers can

usually be removed by annealing.

Machined Surfaces i. Shows a susceptibility to corrosion after ageing

V. Conclusions

Hot rolling and cold rolling results in the formation of thin ultrafine grained surface layers that modify both corrosion performance and surface appearance.
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