Slide 10 of 20
Notes:
This table presents a summary of the 2000 or so analytical results obtained from the parameter test study. The values in the table are actually the mean results obtained for each analyte and welding process, and they cover all the parameters listed in the table on the last slide. Unfortunately, because of the shear volume of data, I only have time to show you this summary table, which just illustrates the overall variability in welding fume composition.
Looking first at the MMA results: Although the current was held constant, small variations in voltage did occur, and the raw data gave a clear indication that where there the observable differences in fume composition, variation in voltage was the primary cause. In particular, the chromium, iron, and nickel contents of the fume were found to increase with arc voltage, and this is reflected in the higher RSDs for these metals.
Turning to the MAG results: Although voltage is generally held constant in MAG welding, different voltages have to be used for wires of different diameters, different shielding gases etc, and there was also some variation in current used. This meant that the determined fume composition was more variable than for the other processes investigated.
Finally, variation in the composition of fume generated from gas shielded FCAW was intermediate between MMA and MAG welding. Once, again voltage seemed to be the main factor affecting fume composition.
