No abstract

The dependences of the geometric characteristics of the melt bath on the scanning velocity and radiation power during laser metal deposition (LMD) are shown. The data were obtained experimentally at different values of the intensity Is up to 60 kW/cm2 in the range of changes in the specific energy per unit surface area Es (20…60) j/mm2 using the high-speed video camera installed in coaxial scheme. A powder (40…100) microns of PR-Kh18N9 austenitic steel with a mass flow rate of 8.4 g/min was used. It is found that the length of the melt pool L increases with the growth of Is and practically does not depend on the scanning velocity in the range (5…10) mm/s. The melt volume is estimated taking into account the measured track height. At the same velocity, the volume of the melt increases with the value of the Is exceeding the threshold. The value of threshold increases with increasing velocity. The volume of the melt increases with the specific energy Es. The relationship between the geometric characteristics of the melt bath and the shape of the track formed in the LMD process is shown.

The dependences of geometric characteristics of single tracks obtained by laser deposition of austenitic steel powder on the shift of the laser beam focus and the distance from the nozzle to the substrate at different values of mass flow and scanning speed are investigated. It is shown that the characteristic value of the track height decreases from 900 to 700 microns with a decrease in the beam size by half at a powder flow rate of 8.4 g/min and a speed of 350 mm/min, decreases from 1100 to 900 microns at a flow rate of 15.6 g/min, and increases by 30-50% with an increase in flow rate by 2.3 times. The ratio of height to width (shape factor) decreases with the growth of the scanning speed from about 0.7 to 0.4 at a flow rate of 15.6 g/min and to 0.25 at a flow rate of 8.5 g/min. Process performance scaling parameters are defined. The results obtained make it possible to optimize the technological parameters of the laser metal deposition process.

No abstract