HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

No abstract

A C02 laser beam was used for welding Si02-A12@ ceramic tubes with 60wt% alumina content. To prevent weld cracking a preheating process with radiant energy produced by halogen lamps and collected by reflectors was used. Several evaluation techniques like helium checking, Vickers indentation and flexural resistance were employed to study weldzone characteristics.

Within the scope of increase in cutting tools efficiency, a CW CO;! laser beam has been used for butt welding sintered tips containing cobalt and tungsten carbide to a medium carbon steel core. After optimization of the laser processing conditions, full penetrating, sound and homogeneous welds are observed. Hardness is found to be nearly constant across the entire weld bead cross-section. Micrographic observations in the same area show a fine dendritic microstructure ; microanalysis (EDS) as well as X-ray diffraction experiments reveal that dendrites contain mainly iron and cobalt, while tungsten has segregated in the interdendritic zone where complex (Fe-CoW) rich carbides are likely to form.

Car exhaust manifolds are critical components subjected to cyclic thermo-mechanical

No abstract

The spectral emission of the laser induced plasma is investigated during the welding process of stainless steel (304 L), titanium (T 40), aluminium and aluminium based alloy (5083). The intensities of the spectrum lines which are emitted from a small area of the plasma are studied as a function of the distance from the surface, wavelength, time and processing parameters

Le soudage d'un acier Z 2 CN 18 par faisceau laser a été étudié. L'influence principaux paramètres vitesse, puissance, focalisation a été examinée. Les moyens classiques de caractérisation des soudures ont été utilisées : observations métallographiques forme de la zone fondue, quantité de porosités et énergie absorbée. Le maximum de pénétration correspond au maximum d'énergie absorbée