The question asks for the method to butt weld two sheets of the same material but different thicknesses.

Welding Different Thicknesses

When welding materials of different thicknesses, ensuring uniform heat distribution and pressure application is crucial for a strong weld. The thickness difference can lead to issues like overheating on the thinner section or insufficient heat on the thicker section.

Evaluating Welding Options

Let's analyze the given options in the context of butt welding sheets with varying thicknesses:

• Adjustment of the current: While current affects heat, simply adjusting it might not fully compensate for significant thickness differences without causing other problems.
• Time duration of current: Similar to current adjustment, managing time alone is often insufficient for large thickness variations.
• Pressure applied: Pressure is essential, but changing only the pressure without altering how it's applied across the varying thickness isn't the primary solution.
• Changing the size of one electrode: In processes like resistance butt welding, the size and shape of the electrodes dictate where pressure is applied and how current is distributed. Using electrodes of different sizes (or shapes) can help compensate for the thickness difference. This allows for more uniform current density and pressure distribution across the joint, promoting a sound weld by managing heat input effectively for both the thicker and thinner sections.

Conclusion

Therefore, changing the size of one electrode is the most direct method to address the challenge of welding sheets with different thicknesses in a butt weld configuration.