Studies on the Electroslag Welding (Report 2)

Infiuence of Welding Conditions on the Penetration of Base Metal

Abstract

In previous report, we described the fundamental mechanism of penetration in electroslag welding considering the current and temperature distribution in slag pool.
In this paper, the influence of some welding conditions (i.e. welding voltage, welding current, slag depth, root gap etc.) on the penetration of base metal is described using a certain flux.
The experimental results are shown in Fig. 1-16. We see in Fig. 1 that the penetration decreases as the welding current is increased over a certain value under a constant terminal voltage. The decrease of penetration in spite of the increase of input power is worth notice, and the reason is given as follows. Fig. 7 illustrates the relation between the penetration and the wire tip position in molten slag pool. We know the penetration is affected by the mode of slag convection which is induced by the pinch effect of current flowing out from the wire tip. We see a poor penetration when wire tip is too near not to touch the molten metal pool, because the hot slag convection does not reach the side wall of base metal. When the wire feed speed is increased, the welding current as well as the steeping length of wire into the pool increases naturally under a constant voltage, and takes the mode of Fig. 7 (c).
For given current, we see the increase of penetration for the increa of welding voltage as shown in Fig. 3. Increase of input power may be one reasen, but the change of wire tip position from Fig. 3 (a) to (b) or (c) is presumed as the main powerful reason.
Effects of slag depth as well as root gap on the penetration shown in Fig. 11-14 can be understood in the same way.