エレクトロスラグ溶接現象の研究(第4報)
ワイヤの溶融速度
1973 年 42 巻 2 号 p. 106-113
詳細
1973 年 42 巻 2 号 p. 106-113
In previous reports, the fundamental mechanism of penetration, and the influence of some welding conditions and elecrtical conductivity of fused flux on the penetration of base metal are described.
In this paper, the melting speed of wire is discussed from the experimental data. The experimental results are as follows.
Under the constant welding voltage, the welding current and the steeping length of wire increases as the wire feed speed is increased (See Fig. 1 and 3). When the welding voltage is increased, the wire feed speed should be decreased to maintain the constant welding current, and the steeping length of wire decreases (Fig. 2).
For flux III, which has good electrical conductivitiy only at higher temperature compared to flux II, the wire feed speed is increased compared to the flux II under the given welding voltage and current and the wire steeping of the former is a little deeper than that of the latter. The reason is that the heat energy in a molten slag pool of flux III concentrates remarkably at wire tip which is already mentioned in previous report (See report 3).
The input energy to the wire is estimated from the melting speed assuming the temperature of molten wire to be 1700°C, and the energy is expressed in the form of equivalent voltage. The resistance drop along the wire is also estimated approximately. These are calculated as shown in Fig. 7. The difference of above two voltages gives the equivalent voltage in heating effect of slag on the wire. From Fig. 7 the equivalent voltage is about 2.3V for flux I (Vt=18V), 6.8V for flux II (Vt=36V) and 8.1V for flux III (Vt=36V). It is interesting that the values remain almost constant independently of the current,
When the slag depth is increased, both the wire melting speed and the equivalent voltage increase. This is due to the increase of steeping surface area of wire in spite of the falling down slag temperature.
When the root gap is decreased wire melting speed decreases under the given welding voltage, current and slag depth. We presume that the reason is due to both falling down of the average temperature of slag pool increase of welding speed and the low heat of slag at the upper zone due to difficulty of convection.
