Abstract
The double pulsed gas metal arc welding (DP-GMAW) process has been effectively employed to realize joining of steel plates and obtain weld bead surfaces with high quality fish scale ripples. In this work, a DP-GMAW process based on robot operation using the latest twinpulse XT DP control technology was employed to join the stainless-steel base plates. Four key operational parameters, which were robot welding speed, twin pulse frequency, twin pulse relation and twin pulse current change in percent, were selected to be input elements of orthogonal experimental design, which included nine experiments with three levels. To accurately understand the performance and process of weld bead obtained from DP-GMAW operation based on robot operation, the appearance observation and key shape parameters measurement, microstructure analysis, tensile and hardness testing, as well as stability analysis of the electrical signals, were conducted. Correlation analysis showed that the grain size was significantly correlative to the toughness and hardness. Then, to obtain quantitative evaluation results, fuzzy comprehensive evaluation (FCE) was employed to provide quality evaluation of weld beads from the above experiments. The influential levels of the key operational parameters on the appearance, grain size and FCE scores, and corresponding physical analyses, were respectively presented. In addition, optimal parameters combinations for obtaining weld beads with optimal appearance, grain size, and the highest FCE scores of weld bead quality were respectively provided according to the range analysis of the results from orthogonal experimental design. This work can provide an effective analysis method of influential levels of key operational parameters on the performance of the weld bead, optimal operational parameters combination seeking method, and quantitative quality evaluation method for the DP-GMAW process, which can improve the process optimization and increase the production efficiency, both in academic research and actual industrial production.
Highlights
The double-pulsed gas metal arc welding (DP-GMAW) process is a mature arc welding operation technology that is prevalently employed in modern industrial manufacturing occasions
During the DP-GMAW process, the current waveform is composed of a rhythmic thermal pulse phase (TPP) and a thermal base phase (TBP) [7], which have different frequencies and amplitudes, and the sum of durations of the two phases is equal to a thermal period (TP) [8]
A comprehensive evaluation index element set can be confirmed as shown in Equation (5): U = {Appearance, grain size, stability of electrical signal, bead height coefficient, penetration, bead width}
Summary
The double-pulsed gas metal arc welding (DP-GMAW) process is a mature arc welding operation technology that is prevalently employed in modern industrial manufacturing occasions. Though this process is designed based on the traditional pulsed-GMAW (P-GMAW), it has some significant merits when compared to the P-GMAW, such as the DP-GMAW process can reduce the porosity incidence [1] and improve the solidification cracking susceptibility [2]. During the DP-GMAW process, the current waveform is composed of a rhythmic thermal pulse phase (TPP) and a thermal base phase (TBP) [7], which have different frequencies and amplitudes, and the sum of durations of the two phases is equal to a thermal period (TP) [8]. The original waveform was a usual types of square waveforms where strong current and weak current were alternately appeared during the process
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