Two mild steel plates of similar thickness, in butt-joint configuration, are welded by gas tungsten arc welding process using the following welding parameters.A filler wire of the same mild steel material having 3 mm diameter is used in this welding process. The filler wire feed rate is selected such that the final weld bead is composed of 60% volume of filler and 40% volume of plate material. The heat required to melt the mild steel material is 10 J/mm³. The heat transfer factor is 0.7 and melting factor is 0.6. The feed rate of the filler wire is ________________ mm/s (round off to one decimal place).
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The feed rate of filler wire in welding is determined based on heat required to melt the material, welding parameters, and the efficiency of the process.
The heat input required for the welding process is given by the formula:
\[
Q = V \times I \times \eta
\]
where:
- \( V \) is the welding voltage (20 V),
- \( I \) is the welding current (150 A),
- \( \eta \) is the welding efficiency (given as \( 0.7 \)).
The total heat input per unit length of the weld is:
\[
Q_{\text{total}} = V \times I \times \eta \times \text{welding speed} = 20 \times 150 \times 0.7 \times 5 = 10500 \, \text{W}
\]
The amount of heat required to melt the material is calculated based on the melting factor:
\[
Q_{\text{melt}} = \text{heat per volume} \times \text{volume} = 10 \times 10^{-3} \times \left( 0.6 \times 0.4 \times \text{filler volume} \right)
\]
Equating the total heat to the heat required for melting:
\[
\boxed{10.9} \, \text{mm/s} \, (\text{rounded to one decimal place}).
\]
