Influence of excessive carbides upon strength of hot rolled rolls of steel similar to high speed grade

in Stal' (2006), 9

This paper will illustrate the choice of the alloying elements and their content in the current grade. By using sophisticated laboratory examination techniques such as differential thermal analysis ... [more ▼]

This paper will illustrate the choice of the alloying elements and their content in the current grade. By using sophisticated laboratory examination techniques such as differential thermal analysis, scanning electron microscopy and image analysis, the metallurgical parameters of Aurora grade will be described and compared to those of the Kosmos grade. An attempt will also be made to connect all our laboratory results to the good behaviour of the alloy in operation in the early stands of Hot Strip Mills. [less ▲]

Determination of solidification parameters used for the prediction of the thixoformability of several steel alloys

in Solid State Phenomena (2006), 116-117

This paper focuses on the liquid fraction curves of several steels and the correlation between liquid fraction, temperature and heating rate. The work has been performed along two main axes. First, the ... [more ▼]

This paper focuses on the liquid fraction curves of several steels and the correlation between liquid fraction, temperature and heating rate. The work has been performed along two main axes. First, the solid fraction versus temperature has been obtained experimentally by differential scanning calorimetry (DSC), limited to low heating rates. Then, a shift of the liquid fraction curves has been noticed at high industrial heating rates. The quantification of this effect could not be carried out by DSC and required the elaboration of another experimental device. [less ▲]

Characterization of Duplex steel Uranus 76N during deformation and heat treatment

in Physica Status Solidi A. Applications and Materials Science (2006), 203(15), 3651-3664

Duplex Uranus 76N is characterized by metallography, thermal and mechanical analysis. The investigation shows that the microstructure of such a Duplex strongly depends on the cooling conditions ... [more ▼]

Duplex Uranus 76N is characterized by metallography, thermal and mechanical analysis. The investigation shows that the microstructure of such a Duplex strongly depends on the cooling conditions determining the quantity of austenite formed in the ferrite matrix. Numerical simulations of 76N behavior during the rolling process and service life require the knowledge of the recrystallization state during rolling steps at high temperature, thermal parameters such as dilatation, density, specific heat, thermal diffusivity, thermal conductivity and mechanical constitutive laws. These material parameters are determined and presented in this study. [less ▲]

Thixoforging of 7075 aluminium alloys at high solid fraction

in Solid State Phenomena (2006), 116-117

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.5 < f(s) < 1), which involves the processing of alloys in the semi-solid state. 7075 alloy has been used as a feedstock for ... [more ▼]

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.5 < f(s) < 1), which involves the processing of alloys in the semi-solid state. 7075 alloy has been used as a feedstock for thixoforming in order to investigate thixoformability of a high performance aluminium alloy at high solid fraction. The microstructure in semi-solid state consists of fine spheroidal solid grains surrounded by liquid. Thixo behaviour allows laminar flow that avoids macro-porosity and other casting defects and gives better mechanical properties; so we can reduce the weight of functional parts. Higher solid fraction of 7075 alloy is less sensitive to temperature, avoids metal splash at high speed, allows laminar flow at high speed and gives a good smooth surface without stick-slip phenomenon. The process is quicker with less energy and so the production rate increases and the tool has longer life. However, high solid fraction promotes freezing flow because of faster solidification and the lack of liquid phase. This freezing flow creates solid/liquid segregation and increases the forming force. [less ▲]

Corrosion behaviour of different hot rolled steels

in Corrosion Science (2006), 48(2), 472-480

The oxidation-corrosion behaviour of hot rolled alloys was examined by electrochemical impedance spectroscopy. The corrosion behaviour of the non-oxidised alloys was first determined in order to have a ... [more ▼]

The oxidation-corrosion behaviour of hot rolled alloys was examined by electrochemical impedance spectroscopy. The corrosion behaviour of the non-oxidised alloys was first determined in order to have a reference behaviour. Then, each alloy was oxidised for 1 and 3 days at 650 degrees C in air and its corrosion behaviour was also determined. For all the alloys, Fe2O3 was formed at the scale-gas interface. However, the Fe2O3 crystallographic structures varied as a function of the alloy composition. Differences in the corrosion behaviour are due to the thickness, the microstructure and the porosity of the scale. The new graphite chromium iron alloy (Hi-Cr + C) have an oxidation-corrosion behaviour close to the indefinite chill double paired (ICDP) one and is therefore thought to be a good candidate to replace the ICPD alloy. In the case of the high speed steel (HSS) alloy, the oxidation-corrosion kinetics are too slow to prevent sticking problems. The Co addition decreases the corrosion-oxidation rates for the non-oxidised and oxidised samples but this effect is limited in time. (C) 2005 Elsevier Ltd. All rights reserved. [less ▲]

Dimensionnement de chariots d'amortisseurs et choix d'accessoires pour machine d'impact

Report (2006)

Etude et faisabilité d'un générateur magnéthothermique, avec dispositif expérimental. Phase 1 : Etude et faisabilité

Report (2005)

Mesures de diffusivité thermique sur 9 tôles de chez OCAS

Report (2005)

Metallographic analyses and Hardness results

Report (2005)

Study of liquid fraction of semi-solids steels for thixoforming

Report (2005)