Publications by Jean-Marie Drezet

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Hot tearing and loss of dimensional stability are two key defects related to industrial aluminum alloy casting processes. In order to investigate their occurrence, a new semi-solid constitutive law [20] for AA5182 that takes into account cooling rate, grain size and porosity has been implemented into a Direct Chill casting process model for round billets. The semi-solid stressstrain predictions provided by this new constitutive law as well as the effects of processing parameters were then examined to demons

Zirconium is always present in Ni base superalloys as it enhances their creep properties. In the present study, the influence of very small Zr additions, 100–400 ppm, i.e. 0.01–0.04 wt.%, on hot tearing of IN738LCsuperalloy is experimentally investigated using dedicated turbine blade castings. Although the Zr content remains very small, it has a strong effect on hot tearing tendency. Microstructure of hot tear in as-cast samples reveal that grain size and secondary dendrite arm spacing have no significant e

This paper describes the numerical analysis method used to estimate welding induced residual stresses in K-shape tubular bridge joints. The knowledge of residual stress distribution is required to design the geometry of K-joints loaded under fatigue stresses. Numerical simulations are focused on the arc welding MAG process, generally used to weld joints in bridge construction. Thermomechanical analyses are performed in 3D using two finite element codes: ABAQUS® and MORFEO®. ABAQUS has the advantage to offer

The prediction of the ingot deformation during direct chiil (DC) and electromagnetic (EM) casting of aluminum alloy slabs would allow the optimization of the moldlinductor shape capable of producing flat ingots. The transient thermomechanical model presented here predicts the deformation and the temperature field evolution during DC/EM casting. Deformation in the solid is assumed to obey a viscoplastic law. The model is validated on the basis of the measurements presented in part I. It enables to predict th

The driving force that causes enlargement of the ventricles remains unclear in case of normal pressure hydrocephalus (NPH). Both healthy and NPH brain conditions are characterized by a low transparenchymal pressure drop, typically 1 mm Hg. The present pape ...

Modelling of hot tearing must encompass several aspects: solidification, percolation of grains, stress/strain development, liquid feeding. The present contribution reviews recent progress made in this domain, both at the macro- and microscopic levels. At t ...

The thermoforming of thermoplastic sandwich structures based on the same matrix polymer for the face sheets and the core requires precise temperature control both before and during forming. Two opposing requirements must be satisfied: the face sheets must be heated to above the glass transition temperature Tg of the polymer whereas the temperature of the core should not approach Tg in order to avoid the collapse of the foam cells. A numerical model was used to determine the optimal thermal parameters for th

In the current trend toward thicker aluminium plates, a major concern is the generation of high internal stresses during quenching, which can cause distortions during machining and pose serious safety concerns. Although the material is stretched after quench, substantially reducing residual stresses, they are not fully suppressed. In addition, the cooling rate is not large enough at the core of such thick plates to prevent any precipitation. This has a great impact on the efficiency of ageing. In this work,

In the fabrication of heat treatable aluminum parts for the aeronautic industry, quenching is a key step to obtain the required mechanical characteristics after aging. For thick plates, thermal gradients cause non-homogeneous plastic strain resulting in re ...

Near interfacial residual stresses are investigated in a joint composed of aluminum alloy and dual phase steel. A small step neutron diffraction scan was initially performed to determine the weld interface position along the measured transverse cross secti ...

The prediction of the ingot deformation during direct chill (DC) and electromagnetic (EM) casting of aluminum alloy slabs would allow the optimization of the mold/inductor shape capable of producing flat ingots. The transient thermomechanical model presented here predicts the deformation and the temperature field evolution during DC/EM casting. Deformation in the solid is assumed to obey a viscoplastic law. The model is validated on the basis of the measurements presented in part I. It enables to predict th

As for most of the topics in the field of solidification, Mert Flemings has always pioneered new ideas. While much of the understanding of hot tearing formation was already known about 30 years ago, he devised with Metz an interesting apparatus for studying the resistance of mushy zones to compression and shearing [1,2]. Part of the results of these tests lead Flemings to become interested in semi-solid processing of metallic alloys, with the success we know today (e.g., production of automobile components

The semicontinuous direct chill (DC) casting of large cross-section rolling sheet ingots of high strength aluminium alloys (2xxx and 7xxx series) gives birth to high residual (internal) stresses generated by a non-uniform cooling. These stresses must be re ...

The deformation and the temperature field within direct chill (DC) and electromagnetic (EM) cast aluminum ingots have been measured in-situ using a simple experimental set-up. The deformation of the cross section of the cold ingots has also been characterized as a function of the casting speed, alloy composition and inoculation condition. The pull-in of the lateral rolling faces has been found to occur in two sequences for DC cast ingots whereas that associated with EMC was continuous. The pull-in was maxim

Cerebrospinal fluid (CSF) is a colourless liquid that fills the ventricular space and serves several functions like buoyancy, chemical stability and protection. CSF is produced within the ventricles and partly by the ependyma cells. Part of it seeps toward ...

A coupled hydromechanical granular model aimed at predicting hot tear formation and stress-strain behavior in metallic alloys during solidification is applied to the semicontinuous direct chill casting of aluminum alloy round billets. This granular model c ...

In many casting processes, some stages, such as the starting phase in the direct chill casting of aluminium alloys, are particularly critical because of the propensity of some alloys to develop either hot tears which initiate at non zero liquid fraction, or cold cracks which nucleate and grow exclusively in the solid metal. Figure 1 shows a cracked rolling sheet ingot: two hot tears initiated during the starting phase of casting have grown up as the ingot was further cast. For some very sensitive alloys, up

As-cast stresses in the foot of the ingot corresponding to the transient start-up phase of the direct chill casting have been determined in aluminum alloy AA7050 rectangular ingots. This high strength alloy is usually cast with a wiper that is placed below ...

A conventional way to determine precipitation kinetics in heat treatable aluminium alloys is to monitor the associated solute loss by in-situ resistivity. A Gleeble machine is used to perform so called isothermal quenching (IQ) resistivity measurements. IQ consists in quenching the alloy down to a given temperature and holding it at this temperature. The results are validated against measurements performed with a classical four-points method using continuous current on the same alloy.

Jean-Marie Drezet

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HOT TEARING SUSCEPTIBILITY IN DC CAST ALUMINUM ALLOYS

Hot tearing in polycrystalline Ni-based IN738LC superalloy: Influence of Zr content

Residual stresses in as-welded joints: finite element modeling and neutron diffraction stress measurements

Thermomechanical Effects during Direct Chill and Electromagnetic Casting of Aluminum Alloys. Part II : Numerical Simulation

Ventricle Equilibrium Position in Healthy and Normal Pressure Hydrocephalus Brains Using an Analytical Model

Towards a Micro-Macro Model of Hot Tearing

Pre-Heating of Thermoplastic Sandwich Materials for Rapid Thermoforming

Residual Stress Analysis in AA7449 As-Quenched Thick Plates Using Neutrons and Fe Modelling

Prediction of quenching-induced stress distribution in 7XXX aluminium alloy thick plates using Gleeble interrupted quench tests

Residual stresses of friction melt bonded aluminum/steel joints determined by neutron diffraction

Thermomechanical Effects during Direct Chill and Electromagnetic Casting of Aluminum Alloys Part II : Numerical Simulation

Study and modeling of hot tearing formation

Fracture prediction during sawing of DC cast high strength aluminium alloy rolling slabs

Experimental investigation of thermomechanical effects during direct chill and electromagnetic casting of aluminium alloys

STUDY AND MODELING OF HOT TEARING FORMATION

Calculation of intracranial pressure in human brain using Darcy's and Biot's models

Prediction of Hot Tear Formation in Vertical DC Casting of Aluminum Billets Using a Granular Approach

Predicting Hot Tearing in Aluminium Castings

Influence of a wiper on residual stresses in AA7050 rolling plate ingots

Monitoring precipitation kinetics in heat treatable aluminium alloys using in-situ resistivity in Gleeble thermomechanical simulator