Adjusting the current

When butt welding two plates of the same metal with equal thickness, the welding process is achieved by adjusting the current. This is because the current plays a critical role in the arc welding process, specifically in terms of heat generation and control.

Explanation:

1. Heat Generation:
- Electric arc welding involves the use of an electric arc between an electrode and the base metal to melt and fuse the metal together.
- The heat required for melting the metal is generated by the electric arc, which is produced by passing a high current through the electrode.
- The current passing through the electrode creates a high-temperature plasma arc, which melts the base metal and the electrode to form a molten pool.

2. Heat Control:
- The amount of heat generated during the welding process is directly proportional to the current passing through the electrode.
- By adjusting the current, the welder can control the amount of heat generated.
- When welding plates of the same metal with equal thickness, the current needs to be adjusted to ensure that the heat generated is sufficient to melt both plates and create a proper fusion zone.
- If the current is too low, it may not generate enough heat to melt the plates properly, resulting in a weak or incomplete weld.
- On the other hand, if the current is too high, it may generate excessive heat, leading to burn-through or distortion of the plates.

3. Other Factors:
- While adjusting the current is the primary means of controlling the heat generation in electric arc welding, other factors such as electrode composition, electrode size, and electrode coating can also affect the welding process.
- However, in the given scenario where the plates have equal thickness, changing the electrode size or coating may not be necessary.
- The electrode size and coating are more commonly adjusted when welding plates of different thicknesses or when specific welding requirements demand it.

Conclusion:

In butt welding two plates of the same metal with equal thickness, the welding process is achieved by adjusting the current. By controlling the current, the welder can regulate the heat generation during the welding process, ensuring proper fusion and a strong weld. While other factors such as electrode size and coating can also affect the welding process, they may not be necessary to adjust in this specific scenario.

Option C