Question

which modes of transfer should not be used when welding aluminum? (check all that apply.)
short circuit
pulse spray
spray
globular

Explanation:

When welding aluminum, short - circuit and globular transfer modes are not suitable. Short - circuit transfer can cause excessive heat input and porosity due to the nature of aluminum's oxide layer and its thermal conductivity. Globular transfer results in large, irregular metal droplets which can lead to poor weld quality, porosity, and lack of fusion when welding aluminum. Pulse spray and spray transfer are more appropriate as they can provide better control over the heat input and droplet transfer for aluminum welding.

Answer:

Short Circuit, Globular