MetFab - Welding Fume Handbook - Flipbook - Page 20
8 Effect of shielding gas: particulate fume
8.1 Mild steel welding
MAG
Generally, shielding gases for MAG welding of mild steel
are mixtures of argon and carbon dioxide or argon, carbon
dioxide and oxygen. Figure 8 illustrates the effect of carbon
dioxide in the shielding gas on fume emission rate during
mild steel welding with pulsed transfer.
26.1
20
I
15.8
15
I
10
I
Fume emission rate mg/s
I
25
8.3
6.3
I
5
0
98% Ar/2% CO
92% Ar/8% CO
85% Ar/15% CO
CO
Figure 8: The effect of welding gas formulation on fume
emission rate during pulsed MAG welding of mild steel
The high emission rate associated with the use of an
Ar/2%C0 mixture is attributable to the welding instability
that occurs with this gas. The same effect is seen in Figures
9 and 10, which also show the effect of a range of shielding
gases on fume emission rate during mild steel welding with
dip and spray transfer.
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