J. Phys. IV France 04 (1994) C4-147-C4-150
On-line thermocycles measurements in laser applicationsI. SMUROV1, V. MARTINO1, M. IGNATIEV2 and G. FLAMANT3
1 Ecole Nationale d'Ingénieurs de Saint-Etienne, 58 rue Jean Parot, 42023 Saint-Etienne cedex 2, France
2 Baikov's Institute of Metallurgy, Russian Academy of Sciences, Leninsky Prospect 49, 117911 Moscow, Russia
3 Institut de Science et de Génie des Matériaux et Procédés, CNRS, BP. 5, Odeillo, 66125 Font-Romeu cedex, France
The thermal state of material in the zone of laser action is one of the main integrated parameters to determine the evolution of physicochemical processes and structural phase transformations. The conditions of temperature measurements in laser machining are among the most severe even for noncontact technique of optical pyrometry. From a general point of view, the absence of on-line control and monitoring is one of the main limitations of laser technology integration into modern industry. Data on surface temperature dynamics obtained by pyrometry could be widely used to : (a) understand and optimize the laser processes (i.e. define of the links between surface temperature history and the properties of treated materials) ; (b) create process control on-line including feedback from a pyrometer. The main technical parameters of high speed pyrometer (HSP) are the following : brightness temperature range 1150K (1550K)-3500K (threshold sensitivity depends on selected wavelength) ; error of measurement 1 % ; response time 190 µs ; 200 µm spatial resolution at 350 mm distance of pyrometer from the zone of temperature measurements ; wavelength variation in 2 colour channels from 0.5 to 1.1 µm. The opportunities of actual temperature measurements by high speed high spatial resolution pyrometer system in wide range of laser applications are illustrated by : heat treatment, welding, cladding, and pulsed action.
© EDP Sciences 1994