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Intermittency and Deformation Band Propagation in an Austenitic FeMnC TWIP Steel

100%

Lebyodkin M., Lebedkina T., Roth A., Allain S.

Acta Physica Polonica A

2012

vol. 122

issue 3

478-481

Plastic deformation of austenitic FeMnC TWIP steels exhibits complex spatiotemporal patterns associated with the occurrence of deformation bands and the concomitant fluctuations of the deforming stress. Although the plastic instability is a generic property of these steels and is usually attributed to interaction of dislocations with solutes (the Portevin-Le Chatelier effect), both the kinematics of the deformation bands and the characteristic shape of stress serrations observed in the carbon-containing TWIP steel at room temperature manifest unusual features. The nature of these peculiarities and the mechanism of jerky flow in such steels are unclear. In the present work, an attempt is made to get an insight into the jerky flow in the Fe22Mn0.6C steel by studying the time series characterizing the evolution of plastic deformation at various scales: stress-time curves, local strain field, and acoustic emission accompanying the deformation processes. Stress and strain fluctuations related to two distinct scale ranges are detected and characterized.

Acoustic-Emission Study of Intermittency of Plastic Flow during Twinning and Dislocation Glide

64%

Shashkov I., Lebedkina T., Lebyodkin M., Dobron P., Chmelik F., Kral R., Parfenenko K., Mathis K.

Acta Physica Polonica A

2012

vol. 122

issue 3

430-434

Recent studies of plastic deformation with the aid of acoustic emission techniques proved an intermittent, scale-invariant character of plastic processes, as reflected in power-law statistical distributions. In some cases, the power-law exponents display close values leading to hypothesis of universality of scaling laws for various mechanisms of plasticity. Nevertheless, the accurate determination of the power law may be impeded by some sources of errors inevitable in real conditions, in particular, by superposition of individual acoustic emission events. In the present work, the sensitivity of the apparent statistics to the variation of the parameters of individualization of acoustic emission events is examined using Mg and Al based alloys. Both these alloys exhibit a highly cooperative character of plastic deformation, leading to strong acoustic activity which is governed by distinct microscopic mechanisms - mechanical twinning and the Portevin-Le Chatelier effect, respectively.

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2 Acta Physica Polonica A

2 2012

2 Lebedkina T.

2 Lebyodkin M.

1 Allain S.

1 Chmelik F.

1 Dobron P.

1 Kral R.

1 Mathis K.

1 Parfenenko K.

1 Roth A.

1 Shashkov I.

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Intermittency and Deformation Band Propagation in an Austenitic FeMnC TWIP Steel

Acoustic-Emission Study of Intermittency of Plastic Flow during Twinning and Dislocation Glide