AWS Welding Inspection and Testing Certification Practice Test

In which situation would you most likely see incomplete fusion when welding?

1. When using the spray transfer method

2. When utilizing short circuit transfer mode

3. During non-pulsed MIG welding

4. Using thin welding wire

The correct answer is: When utilizing short circuit transfer mode

Incomplete fusion commonly occurs during the short circuit transfer mode due to the nature of the welding process itself. In this mode, the molten metal is transferred to the workpiece through short circuits that occur as the electrode touches the base material. This rapid melting and cooling can sometimes lead to insufficient heat input at the edges of the weld pool, preventing the filler metal from adequately merging with the base material. This inadequate heat can result in areas that are not fully fused, especially when the welding conditions or technique are not optimal. While other methods of welding can also lead to issues with fusion, short circuit transfer is particularly prone to this problem due to the specific dynamics of metal transfer and the cooling rates involved. Understanding this phenomenon is critical in ensuring strong welds and preventing potential failures in the weld joint.