Study of dynamic strain aging in dual phase steel

► Characterization of the high temperature mechanical behavior of a dual phase steel. ► Determination of the effect of dynamic strain aging on the strain hardening rate. ► Identification of the mechanism associated with dynamic strain aging. ► The value of the interaction energy carbon–dislocation i...

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Bibliographic Details
Published in:	Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 543; pp. 84 - 87
Main Authors:	Queiroz, R.R.U., Cunha, F.G.G., Gonzalez, B.M.
Format:	Journal Article
Language:	English
Published:	Kidlington Elsevier B.V 01-05-2012 Elsevier
Subjects:	Applied sciences Cross-disciplinary physics: materials science; rheology Dual phase steels Dynamic strain aging Elasticity. Plasticity Exact sciences and technology Materials science Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology Metals. Metallurgy Physics Solid solution, precipitation, and dispersion hardening; aging Treatment of materials and its effects on microstructure and properties Work hardening Work hardening Dynamic strain aging Dual phase steels Plastic flow Tension test Tensile strength Strain ageing Precipitation Yield strength Dual phase steel Serrated yielding Activation energy Portevin Le Chatelier effect Dynamic load Strain rate
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Summary:	► Characterization of the high temperature mechanical behavior of a dual phase steel. ► Determination of the effect of dynamic strain aging on the strain hardening rate. ► Identification of the mechanism associated with dynamic strain aging. ► The value of the interaction energy carbon–dislocation in ferrite was confirmed. The susceptibility to dynamic strain aging of a dual phase steel was evaluated by the variation of mechanical properties in tension with the temperature and the strain rate. The tensile tests were performed at temperatures varying between 25°C and 600°C and at strain rates ranging from 10−2 to 5×10−4s−1. The studied steel presented typical manifestations related to dynamic strain aging: serrated flow (the Portevin–Le Chatelier effect) for certain combinations of temperature and strain rates; the presence of a plateau in the variation of yield stress with temperature; a maximum in the curves of tensile strength, flow stress, and work hardening exponent as a function of temperature; and a minimum in the variation of total elongation with temperature. The determined apparent activation energy values, associated with the beginning of the Portevin–Le Chatelier effect and the maximum in the variation of flow stress with temperature, were 83kJ/mol and 156kJ/mol, respectively. These values suggest that the mechanism responsible for dynamic strain aging in the dual phase steel is the locking of dislocations by carbon atoms in ferrite and that the formation of clusters and/or transition carbides and carbide precipitation in martensite do not interfere with the dynamic strain aging process.
ISSN:	0921-5093 1873-4936
DOI:	10.1016/j.msea.2012.02.050