Studies on the Electroslag Welding (Report 3)

Influence of Electrical Conductance of Flux on the Penetration of Base Metal

Abstract

We described the fundamental mechanism of penetration and the influence of some welding conditions on the penetration of base metal in previous reports 1 and 2.
This paper describes the influence of electrical conductance of molten slag on the penetration using some different fluxes.
Fig. 2 shows the temperature characteristics of conductance of fluxes I, II and III used in our present investigation, flux es II being the same one as used in reports 1 and 2. Flux I has high conductivity even at low temperature, and flux III has conductivity only at higher temperature than flux II.
The experimental results are as follows;
Though the penetration for flux III shows the same tendency as flux II, which is already described in report 2, it is remarkable that the penetration for flux III is deeper in spite of the deeper steeping of wire in molten slag pool. This is contrary apparently to the conclusion obtained in report 2, where the deeper steeping of wire corresponds to poorer penetration in overcurrent range. We presume that the higher penetraion for flux III is due to the higher working temperature of molten slag. It maybe intresting to cmpare; the welding phenomena of flux III with that of arc welding, regarding the arc atmosphere as molten slag which has conducti ity only in high temperature range.
Using flux I, the wire feed speed should be reduced to keep certain welding conditions. The steeping length of wire is naturally very shallow and the welding current from the wire flows out mainly in the upper zone of slag pool as shown in Figs. 10 and 11, and results in a poor penetration of base metal.
When shallow slag depth is used, the penetration is naturally improved as shown in Fig. 14.