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1

Seizing Effect in the Roller Burnishing Process

100%

Gambin W.

Acta Physica Polonica A

|

1996

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vol. 89

|

issue 3

371-375

EN

Micrographs of metal surface layers after the roller burnishing process show that while about 90% of surface layer thickness is displaced forwards of a roller motion, a thin contact zone undergoes a backward displacement. This seizing effect is caused by a softening of the contact zone due to overheating of the material, during high speed rolling, or due to the plastic strain cumulation in the layer after multiple rolling repetition. The effect is responsible for a peeling and cracking of surface layers during the burnishing process. The plastic analysis of the process taking into account the above effect is presented in the paper. The proposed slip-line field and corresponding velocity field are modification of the simplified solution for the rolling of the rigid-plastic half-space given by Collins.

2

Natural Surface Layer of Metals

63%

Starzyński G., Gambin W.

Acta Physica Polonica A

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1996

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vol. 89

|

issue 3

377-381

EN

A notion of natural surface layer of metals as a reference state for a mechanical description of technological surface layers is introduced. According to experimental observations it is assumed that the yield stress of metal surface layer without any technological treatment is lower than in the bulk material. A simple mechanical model that enables one to find a yield stress distribution in the natural surface layer is proposed. As an example the natural surface layer of aluminium specimen is examined. According to the model and experimental observations, a layer thickness is equal 2-3 grains' diameters, and the yield stress in the layer may be 30% lower than in the bulk material.

3

Problems of Mechanics of Metal Surface Layers

63%

Gambin W., Skalski K.

Acta Physica Polonica A

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1996

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vol. 89

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issue 2

145-154

EN

Mechanics of metal surface layers deals with a description of the following objects, quantities and processes: structures and mechanical properties of metal surface layers after a heat, chemical, electro-chemical or physical treatment; evolution of these structures and properties during mechanical treatments; mechanical behaviour of the layers during exploitation processes. This branch of mechanics is based on the results of physical investigations, but it uses a mechanical approach. In the paper, descriptions of metal surface layers within the classical anisotropic plasticity, large strain plasticity, and finally, the crystal and polycrystal plasticity are recalled. Problems connected with a formulation of laws governing a surface layer behaviour are comprehensively discussed.

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3 Acta Physica Polonica A

3 1996

3 Gambin W.

1 Skalski K.

1 Starzyński G.

Seizing Effect in the Roller Burnishing Process

Natural Surface Layer of Metals

Problems of Mechanics of Metal Surface Layers