FLUX-CORED ARC-WELDING - ARC SIGNALS, PROCESSING AND METAL TRANSFER CHARACTERIZATION

Metal droplet transfer in flux cored are welding (FCAW) was studied us ing electrical are signals and droplets collected from the welding pro cess. A large number of metal droplets from the FCAW experiments was c ollected. According to the size distribution of the droplets, several metal transfer modes could be identified amongst which spray transfer predominated. The electrical are signals, in particular, voltage, were processed using the fast Fourier transform (FFT) technique. Character istic spectral frequencies corresponding to different metal transfer m odes were identified. The size distribution of the collected droplets correlated extremely well with these characteristic frequencies. The e lectrode melt rate, calculated using the characteristic frequencies id entified from the FFT analysis, agreed closely with the measured melt rate. Results from the are signal analysis and the FFT analysis showed that both are voltage fluctuations (Delta u) and characteristic frequ encies of the FFT spectra were adequate to distinguish the different k inds of metal transfer modes in FCAW. Metal transfer mode maps, constr ucted using the two sets of results, were used to determine the optima l parameters for E71T-1, 1/16-in.-diameter electrode, and Ar-25%CO2 sh ielding gas.