What type of arc transfer is associated with STT?

• A. Short circuit
• B. Spray
• C. Globular
• D. Pulsed spray

Answer: (A)

Surface Tension Transfer is a form of metal transfer used in GMAW that operates as a short-circuit transfer. In STT, a small droplet forms at the wire tip and is held by surface tension as the arc length fluctuates. When conditions allow, the current re-ignites and the droplet is transferred across the arc into the weld pool. This surface-tension control produces very small, consistent droplets, low heat input, and minimal spatter, giving a stable arc and smooth bead, especially on thin materials. This is different from spray transfer (tiny droplets at high current, lots of heat), globular transfer (large droplets that tend to spatter), or pulsed spray (spray with pulsed current). STT’s defining characteristic is the short-circuit transfer driven by surface tension to control droplet detachment.