Abstract
Effect of groove width on wire melting rates and characteristics of welding arcs have been studied in DCSP and DCRP-MIG welding (shielding gas composition;80 %Ar+20 % CO2).
In DCSP, it was found that wire melting rate increased as groove width increased, and wire melting rate became a constant value as groove width was wider than some boundary width. In cases where groove width was narrow, welding arcs burned not only at groove bottom but also on both groove faces. Their arc flames were extended and wire tapered end had a tendency to be lengthened and sharpened. At the same time droplets became small and transfered smoothly (spray transfer).
On the other hand, in DCRP, characteristics of arc and wire melting rates were not affected by groove width.
The results are explained in terms of the change of magnetic force and wandering area of cathode spot around the conical tapered wire end.
