Leo Kestens

Prof. Leo Kestens

Metal Science and Technology Group, Ghent University, EEMMeCS Department, B-9052 Ghent, Belgium
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Research Focus & Metrics

Academic Career Length

22Years (2005-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 September 2016 in Materials Science and Technology
Verified
Journal Article
Closed access
LKLeo Kestens
Leo Kestens
HPH. Pirgazi
H. Pirgazi
The present paper gives a concise overview of a number of current issues in the literature on texture formation in alloys with cubic crystal structures, mainly steel and aluminium alloys. As crystallographic texture determines to a large extent the anisotropy of material properties, it is of paramount importance to understand and control the physical mechanisms by which the texture is formed in the subsequent stages of metals manufacturing processes. In the present overview three key solid-state transformation processes are considered: allotropic phase transformations, plastic deformation and recrystallisation. The intention is to highlight a number of key elements in the literature and some recent tendencies, which may provide some insight to scientists and engineers dealing with texture issues in daily practice.

1 April 2014 in Electrochemistry Communications
Verified
Journal Article
Open access
EME. Martinez-Lombardia
E. Martinez-Lombardia
LLL. Lapeire
L. Lapeire
VMV. Maurice
V. Maurice
Iris De GraeveIris De Graeve
Iris De Graeve
Kim VerbekenKim Verbeken
Kim Verbeken
HTHerman Terryn
Herman Terryn

30 September 2020 in Materials
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Journal Article
Open access
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ADAndries Daem
Andries Daem
PSPeter Sergeant
Peter Sergeant
LDLuc Dupré
Luc Dupré
SCSomsubhro Chaudhuri
Somsubhro Chaudhuri
VBVitaliy Bliznuk
Vitaliy Bliznuk
LKLeo Kestens
Leo Kestens
The energy efficiency of electric machines can be improved by optimizing their manufacturing process. During the manufacturing of ferromagnetic cores, silicon steel sheets are cut and stacked. This process introduces large stresses near cutting edges. The steel near cutting edges is in a plastically deformed stress state without external mechanical load. The magnetic properties of the steel in this stress state are investigated using a custom magnetomechanical measurement setup, stress strain measurements, electrical resistance measurements, and transmission electron microscopic (TEM) measurements. Analysis of the core energy losses is done by means of the loss separation technique. The silicon steel used in this paper is non-grain oriented (NGO) steel grade M270-35A. Three differently cut sets of M270-35A are investigated, which differ in the direction they are cut with respect to the rolling direction. The effect of sample deformation was measured—both before and after mechanical load release—on the magnetization curve and total core energy losses. It is known that the magnetic properties dramatically degrade with increasing sample deformation under mechanical load. In this paper, it was found that when the mechanical load is released, the magnetic properties degrade even further. Loss separation analysis has shown that the hysteresis loss is the main contributor to the additional core losses due to sample deformation. Releasing the mechanical load increased the hysteresis loss up to 270% at 10.4% pre-release strain. At this level of strain, the relative magnetic permeability decreased up to 45% after mechanical load release. Manufacturing processes that introduce plastic deformation are detrimental to the local magnetic material properties.

21 November 2016 in Metals
Verified
Journal Article
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FCFelipe M. Castro Cerda
Felipe M. Castro Cerda
LKLeo Kestens
Leo Kestens
ALBERTO MONSALVEALBERTO MONSALVE
ALBERTO MONSALVE
Roumen H. PetrovRoumen H. Petrov
Roumen H. Petrov
The microstructure and texture evolution of cold-rolled low carbon steel after ultrafast heating and quenching is investigated. Experiments were carried out at heating rates of 150 °C/s and 1500 °C/s. The recrystallization of ferrite is studied by scanning electron microscopy and electron backscattered diffraction techniques. The texture evolution of cold rolled steel during ultrafast heating was studied, making it possible to estimate the precise effect of heating rate on the orientations of newly formed grains. The experimental results showed that the recrystallization of ferrite was not completed before the full transformation of austenite. The noticeable increase in the fraction of recrystallized grains of diameter less than 1 µm, when the heating rate is increased from 150 °C/s to 1500 °C/s suggests that the increase of the heating rate enhances the nucleation of ferrite. The crystallographic orientations in recrystallized ferrite are strongly influenced by the heating rates. The effect of heating rate in the releasing of stored energy, carbon diffusion and spheroidization of cementite might explain some differences in textures observed in recrystallized ferrite.

1 September 2019 in Materials Science and Engineering: A
Verified
Journal Article
Closed access
HLHarishchandra Lanjewar
Harishchandra Lanjewar
SNSoroosh Naghdy
Soroosh Naghdy
FVFlorian Vercruysse
Florian Vercruysse
LKLeo Kestens
Leo Kestens
PVPatricia Verleysen
Patricia Verleysen