Which statement correctly describes short-circuit transfer and spray transfer in GMAW, and when each is used?

• A. Short-circuit transfer uses a high current and thick spray for deep penetration.
• B. Short-circuit transfer uses a low current and dip-transfer arc for thin sections and all positions; spray transfer uses higher current with a fine spray of droplets for flat/horizontal positions and thicker sections, delivering higher deposition with smoother beads but requiring clean surfaces and stable shielding.
• C. Short-circuit transfer and spray transfer are identical.
• D. Short-circuit transfer is for aluminum; spray for steel.

Answer: (B)

Short-circuit transfer involves a low current and voltage, with the wire touching the workpiece and forming tiny, controllable droplets that short into the weld pool. This mode is ideal for thin materials and all welding positions because it keeps heat input relatively low and is forgiving of gaps or poor fit-up, making it easier to control bead shape with a dip-transfer action.

Spray transfer uses a higher current and a shielding gas to produce a continuous spray of very small droplets. It delivers higher deposition rates and smoother beads, and it’s best in flat or horizontal positions (and on thicker sections) where heat conduction and stable arc conditions can be maintained. It also requires clean surfaces and stable shielding because contamination or gas instability can disrupt the spray and cause defects.