Improper Interpretation of Dilatometric Data for Cooling Transformation in Steels

Abstract Dilatometry is the most commonly method of producing CCT diagrams and analyzing phase transformations during cooling (as well as transformations during heating) and it permits the real-time monitoring of the extent of reaction in terms of dimensional changes due to phase transformation. All modern dilatometers are fitted with computerised systems which collect dimensional change signals versus temperature to plot a dilatometric curve and also to calculate and plot the derivative of the relative dimensional change with respect to temperature. Unfortunately, elaborated by dilatometers manufacturers software, in many cases could lead to wrong interpretation of phase transformations during cooling.

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Recent Developments of Magnetic SMA

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.59.1 ◽

2008 ◽

Vol 59 ◽

pp. 1-10 ◽

Cited By ~ 8

Author(s):

Outi Söderberg ◽

Ilkka Aaltio ◽

Yan Ling Ge ◽

Xu Wen Liu ◽

Simo Pekka Hannula

Keyword(s):

Magnetic Field ◽

Phase Transformation ◽

Shape Memory ◽

Dimensional Change ◽

Magnetic Shape Memory ◽

Dimensional Changes ◽

Different Types ◽

Recent Developments ◽

Giant Magnetocaloric Effect ◽

The Magnetic Field

In the shape memory alloys (SMAs) the thermal triggering induces reversible dimensional change by the phase transformation – these materials may also be ferrior ferromagnetic, however, here only the ferromagnetic SMAs are discussed. In certain SMAs the austenitemartensite phase transformation is influenced by the magnetic field as either austenite or martensite is promoted by the field and this is exploited for the dimensional changes. However, in the magnetic shape memory (MSM) alloys no phase transformation occurs as the remarkable dimensional changes take place by the twin variant changes in the martensitic phase activated by the external magnetic field at constant temperature. In addition to the phase transformation or magnetic shape memory effect, the applied magnetic field may also result in the conventional magnetostriction (MS), enhance the superelasticity (magneticfieldassisted superelasticity MFAS) or induce the giant magnetocaloric effect (GMCE). Certain alloys such as NiMnGa may even be multifunctional showing more than one of these effects. The present paper gives an overview of the different types of the magnetically activated SMA alloys, their properties as well as their potentials for applications in the frameworks of the recent studies.

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A case study of real-time monitoring of solid-state phase transformations in acoustically levitated particles using near infrared and Raman spectroscopy

European Journal of Pharmaceutical Sciences ◽

10.1016/j.ejps.2012.10.001 ◽

2013 ◽

Vol 48 (1-2) ◽

pp. 97-103 ◽

Cited By ~ 18

Author(s):

Sönke Rehder ◽

Jian X. Wu ◽

Julian Laackmann ◽

Hans-Ulrich Moritz ◽

Jukka Rantanen ◽

...

Keyword(s):

Raman Spectroscopy ◽

Solid State ◽

Phase Transformations ◽

Real Time ◽

Near Infrared ◽

Real Time Monitoring ◽

Infrared And Raman Spectroscopy

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Real time monitoring of phase transformation and strain evolution in LTT weld filler material using EDXRD

Journal of Materials Processing Technology ◽

10.1016/j.jmatprotec.2014.06.008 ◽

2014 ◽

Vol 214 (11) ◽

pp. 2739-2747 ◽

Cited By ~ 9

Author(s):

J. Gibmeier ◽

E. Held ◽

J. Altenkirch ◽

A. Kromm ◽

Th. Kannengiesser ◽

...

Keyword(s):

Phase Transformation ◽

Real Time ◽

Filler Material ◽

Real Time Monitoring ◽

Strain Evolution

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Interpretations of Cooling Dilatograms in the Range of the Bainitic and Martensitic Transformations/ Intwerpretacja Dylatogramów Chłodzenia W Zakresie Przemiany Bainitycznej I Martenzytycznej

Archives of Metallurgy and Materials ◽

10.2478/amm-2014-0284 ◽

2014 ◽

Vol 59 (4) ◽

pp. 1679-1683 ◽

Cited By ~ 1

Author(s):

J. Pacyna

Keyword(s):

Phase Transformation ◽

Phase Transformations ◽

Martensitic Transformations ◽

Lower Bainite ◽

Correct Interpretation ◽

Dilatometric Curve ◽

Treatment Technologies ◽

The Stability ◽

Kinetics Of ◽

Undercooled Austenite

Abstract The method of interpretation of cooling dilatograms of undercooled austenite during its transformation into upper and lower bainite (UB and LB) and into martensite (M), applied in the Laboratory of Phase Transformations of AGH University of Science and Technology in Krakow, is presented in the hereby paper. The relation of the mechanism of the mentioned above transformations to places on the dilatometric curve where transformations start and where they are continued was indicated. An appeal for the unified, correct interpretation of dilatograms of phase transformations, in all laboratories of the world, was formulated. This will allow the formation of equally accurate diagrams of the kinetics of phase transformation of undercooled austenite at its continuous cooling (CCT). In consequence, this could provide a development of more advanced heat treatment technologies. Such approach will also allow for the correct assessment of the influence of the alloying elements on the stability of austenite and phase transformation temperatures at its cooling.

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