This set of Welding Quiz focuses on “Arc Welding Methods”.
1. Why is carbon used in carbon arc welding?
a) Generation of more heat at electrode tip
b) Generation of less heat at electrode tip
c) Provides coating
d) Fixed polarity is maintained
Explanation: Carbon is used in carbon arc welding, at the negative terminal of the cathode. The reason for employing carbon at the negative terminal is that, a lesser amount of heat is generated at the electron tip than at the workpiece.
2. What is the temperature at the negative terminal in carbon arc welding?
3. The process of carbon arc welding is not used for which of the following material?
Explanation: The process of carbon arc melting is widely used for copper and copper alloys, hence bronze and brass are treated by this method. Aluminium can also be treated likewise, but not iron metal.
4. Which gas is used as a protection in carbon arc welding?
a) Carbon dioxide
b) Carbon monoxide
c) Carbon tetra fluoride
Explanation: In carbon arc welding, there has to be a protection to be provided to the molten weld. This protection is provided in the form of an envelope by using a long arc giving carbon monoxide gas.
5. What is the temperature at the positive terminal in carbon arc welding?
Explanation: Carbon is used in carbon arc welding, at the negative terminal of the cathode and the metal which is being worked upon functions as the positive terminal. The temperature of the electrode at the positive terminal is 3900°C.
6. What is the temperature of the negative electrode in metal arc welding?
Explanation: In metal arc welding, the temperature of negative electrode is higher than the temperature of positive electrode. The temperature produced in a negative electrode of a metal arc weld is about 2400°C.
7. What is the temperature of the positive electrode in metal arc welding?
8. Which bead character is seen due to too high welding current?
a) Pilling of metal
b) Pilling of weld metal
c) Excess splatter
d) Small bead formation
Explanation: On provision of too low current, there is pilling of metal seen. When the voltage provided is very high, beads formed are too high. When the speed of weld is less, pilling of weld metal takes place and when welding currents are too high, excessive splatter formation occurs.
9. A smooth and regular bead cannot be formed in metal arc welding.
Explanation: Before the welding starts, the machine has to be adjusted very correctly. The current to be supplied and the voltage to be applied should not to be too low or high, and the welding speed should be normal. By doing this, regular and smooth beads will be formed.
10. Carbon is intended to be mixed in small amounts in the weld, in carbon arc welding.
Explanation: In carbon arc welding, the carbon is present at the negative electrode, where the electrode temperature is at 3200°C. This temperature is lesser than that at the positive electrode. Carbon electrode is kept at a lower temperature on the negative electrode, to avoid the mixing of carbon in the weld. If the carbon gets mixed with the weld, the weld might end up becoming brittle.
Sanfoundry Global Education & Learning Series – Welding.
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