What is the minimum amount of argon shielding gas that must be used to obtain spray transfer?

Spray transfer in welding, particularly in processes like Gas Metal Arc Welding (GMAW), requires a specific composition of shielding gas to achieve optimal results. Using argon as the primary shielding gas is essential because it provides several benefits, including a stable arc and improved penetration.

Having a minimum of 90% argon is necessary to facilitate spray transfer due to its physical properties. The high percentage of argon helps maintain an appropriate temperature in the weld pool, allowing for the formation of small droplets of molten metal that can be transferred across the arc in a consistent and controlled manner. This results in a smoother, more efficient weld with reduced spatter.

Lower percentages of argon, such as those represented by the other choices, do not provide the same level of arc stability or droplet control, which can lead to issues such as a less desirable weld appearance or increased spattering. Therefore, 90% is the threshold needed to effectively enable spray transfer.