Parameterization of the characteristics of the melt pool using the video diagnostics of the laser metal deposition process

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.

Analysis of the intermittent laser-induced thermocapillary convection of the melt by the method of short-time correlation

“…The experiments were carried out at the LMD research facility described earlier [5]. The installation uses the ytterbium fiber-optic laser with the power of up to 400 watts and the wavelength of 1.07 microns.…”

The applying of the short — term cross correlation in optical diagnostics of melt convection in laser metal deposition

“…An overview of the methods of optical diagnostics is given in [9]. To determine the geometric characteristics of MP in the MODC, a high-speed camera Mikrotron 3110 was used [10]. The total magnification of the "focal lens -tele lens x2.2 -lens" system was x1.…”

“…It makes sense to find correlations only for a small sample in the long-time video sequence of data. The length of the melt pool is less than 2D [10] and the short term defines as ±𝐷/𝑉, where the width of the melt pool D is 0.76 mm. The STCC T-A data is presented in figure 3 with the averaging of the initial data of 3 ms and the short sample length of 30 samples.…”