Which of the following modes of metal transfer for the GMAW process uses the lowest energy?

Short Circuiting Transfer is considered to use the lowest energy mode of metal transfer in the Gas Metal Arc Welding (GMAW) process. In this mode, the welding wire makes contact with the molten weld pool, creating a short circuit. This contact momentarily halts the arc until the heat generated from the short circuit melts the wire sufficiently to break the circuit, allowing the arc to reignite.

This process occurs at a lower voltage and current compared to other modes such as Spray Transfer, where a much greater amount of energy is used to create a fine mist of molten metal droplets that transfer across the arc without short circuiting. The energy required for Globular Transfer is also higher, since it involves larger droplets that require enough energy to overcome gravitational forces and effectively transfer from the wire to the weld pool. Underwater Arc Transfer is not relevant in typical GMAW applications, as it involves high energy due to the need to maintain an arc under water conditions.

Therefore, Short Circuiting Transfer stands out as the mode that operates with the least energy expenditure, making it suitable for welding thin materials and in applications where lower heat input is critical.