Final answer:
In GMAW, the Short-circuit or cold transfer method provides the lowest heat, which can lead to incomplete fusion due to insufficient heat being applied to the base metal.
Step-by-step explanation:
The type of metal transfer in Gas Metal Arc Welding (GMAW) that provides the lowest amount of heat to the work piece and is therefore prone to incomplete fusion is known as the cold transfer, also referred to as Short-circuit transfer. This process involves the electrode wire making contact with the weld pool and creating a short circuit. Due to the low heat input, the process is useful for welding thin metals or working in out-of-position welds, but there is an increased risk of incomplete fusion or cold lapping, where the weld does not adequately fuse with the base metal.