Validation of evaporation-determined model of arc-cathode coupling in the peak current phase in pulsed GMA welding

Abstract

A first experimental validation of the EDACC (evaporation-determined arc-cathode coupling) model is performend by comparing the experimental and simulated current in the peak current phase of a pulsed GMAW (gas metal arc welding) process. For this, the EDACC model was extended to limit the cathode surface temperature to a realistic value of <2400K. The information on the plasma for the EDACC model was gathered from literature and extrapolated and extended according to qualitative reasoning. The information on the cathode surface of the EDACC model was derived from a steady-state simulation of the weld pool, using an averaging approach over time for the energy and current. The weld pool surface temperature was compared to pyrometric measurements, that were performed for this work, and the agreement was found to be fair. The observed agreement between the modelled and experimentally determined current was within 10%. As strong assumptions were made for the comparison, the validation cannot be considered as final, but the assumptions are thoroughly analyzed and discussed. However the critical link between surface temperature, plasma temperature and total current transmitted could be reconstructed.

Effect of Arc Behaviour and Metal Transfer Process on Aluminium Welds during Ultrasonic Frequency Pulsed GMAW

“…Detecting the effective arc edge became the main purpose in order to obtain the diameter of arc root (D r ), arc length (L) and arc projection width (D p ), as shown in Figure 1c, which are the most vital characterization parameters of the arc shape. As for Figure 1c, Figure 1c(1) is the original map captured by a high-speed camera, the regions of interest (ROI) are selected to highlight the feature areas and reduce the computational cost, as shown in Figure 1c(2), in grey in Figure 1c(3), median filtered in Figure 1c(4), the greyscale value 240 is binarized in Figure 1c(5), the ROI is reset to delete the reflections from the copper torch in Figure 1c (6), and a record of the highest point coordinate of the arc column and a reset of the grey-scale map by turning the greyscale value to 0 above the highest point is shown in Figure 1c (7). Taking a greyscale value, 100, to binarize again, as shown in Figure 1c(8), the arc column edge is finally captured; hence, the pixel values of D r , L and D p were easy to count.…”

“…Pulsed-ultrasonic-assisted GMAW was analysed by Chen et al [3][4][5]; the results showed that arc length was compressed, metal transfer frequency increased, and weld appearance and mechanical properties were improved with the growing pulsed frequency. Simon [6] compared the experimental and simulated current in the peak current phase of GMAW-P process with an evaporation-determined arc-cathode coupling model, which reconstructed the critical link between surface temperature, plasma temperature and total current transmitted. Sathishkumar et al [7,8] proposed that double-pulsed GMAW had an increased cooling rate, refined grain, better mechanical property, and element segregation was completely precluded.…”