The welding laboratory located at the Commissariat à l’Energie Atomique et Aux Energies Alternatives (CEA) Valduc center in France uses pulsed and continuous wave (CW) laser sources to assemble metallic parts of low thicknesses.
Laser beam welding is characterized with its high power density and the generation of a steam capillary called “keyhole” (see figure 1) due to the overpass of the vaporization temperature of the metal. Around the keyhole, a liquid metal pool is cooling down and forms the welded joint.
This article discusses the results obtained by the recent implementation of the In-process Depth Meter (IDM) of PRECITEC keyhole depth measurement sensor in our laboratory. This distance measurement technology uses a Michelson interferometer adapted to the very special conditions of the laser beam welding.
Micrographs of pulsed welding tests on 316L stainless steel, TA6V plane sheets butt joints are analyzed and compared to the inline collected signals. The system’s ability to follow dynamically the formation of the keyhole into the molten metal is evaluated and compared to numerical models performed in the lab using the finite element COMSOL Multiphysics® software.