FUME GENERATION RATES FOR STAINLESS-STEEL, NICKEL AND ALUMINUM-ALLOYS

This paper describes a study of the effects of pulsed welding current on fume produced during gas metal are welding (GMAW) of stainless stee l, nickel, and aluminum alloys. This is an extension of earlier studie s of mild steel electrode wire. Reduction of welding fume is important because steady current GMAW of stainless steels and nickel alloys may produce fume that exceeds recommended worker exposure limits for some of the fume constituents. Fume generation from aluminum alloy ER5356 was studied because steady current welding with this alloy produces mu ch higher fume generation rates than ER4043 alloy electrode wire. This work shows that pulsed current can reduce GMAW fume generation rates for ER308L, ER310, and ER312 stainless steel, ERNiCr-3 nickel alloy, a nd ER5356 aluminum-magnesium alloy electrode wires. The minimum fume g eneration rates that were measured for pulsed current using the stainl ess steel electrodes were between 25 and 50% of the fume generated usi ng steady current at the same wire feed speeds. Minimum fume generatio n rates for ERNiCr-3 electrode wire using pulsed welding current were between 50 and 85% of those for steady current at the same wire feed s peeds. Pulsed current dramatically reduced the fume generation rate fo r ER5356 aluminum-magnesium alloy electrode wire compared to that for steady current. The fume generation rates measured for the ER5356 elec trode with steady current range from about 3 to over 6 g/min. The fume generation rates for pulsed current welding with ER5356 electrode wir e were between 0.5 and 1.0 g/min. There was no significant difference in fume generation rates between pulsed and steady current for the 0.0 45-in. (1.2-mm) diameter ER4043 electrode wire tested. The minimum fum e generation rate was very low for this electrode with both types of c urrent. Analysis of fume composition from ER308L stainless steel shows that pulsed current does not significantly alter the composition of f ume compared to that produced with steady current.