On the connection between the energy parameters of secondary emission signals from the laser beam welding zone in vacuum with the parameters of metal penetration

Abstract

Currently, laser beam welding is widely used in engineering, especially in the production of responsible appointment. The implementation process of laser beam welding in the production gives such advantages as a high concentration of thermal effects, high growth rate and reducing the temperature in the processing zone, and the possibility of rapid formation of a welded bath in a given volume. In recent years, active development in laser beam technologies in the manufacture of general and special machine building products has been obtained by welding with a concentrated laser beam in a vacuum, which allows producing defect-free welds with a high seam depth to width ratio. Previously, these quality indicators could be observed only with the use of electron beam welding. Studies of physical processes during laser beam welding in a vacuum, in order to create efficient welding technology, is now just beginning. One of the research areas is the possibility of operative control of the process of formation of a welded seam, in order to ensure the absence of defects and high reproducibility of the quality of welded joints. The proposed method is based on registration of secondary emission signals of the welding zone with the use of a collector of charged particles. The amplitude-time characteristics obtained for the given registration can be used to estimate the value of the specific power introduced into the article to be welded. The change in the specific power was recorded during the experiments with a change in the focus of the laser beam relative to the surface being treated, which makes it possible to conclude that the emissivity has changed from the weld pool. The use of this technique for recording the secondary emission current recorded in the plasma over the laser welding zone in a vacuum provides the possibility of an operative control of the geometry of the penetration zone during laser welding in vacuum.