AWS Welding Inspection and Testing Certification Practice Test

Which discontinuity occurs when the weld metal fails to fuse with the base metal?

1. Porosity

2. Undercut

3. Lack of fusion

4. Cracking

The correct answer is: Lack of fusion

The correct answer is that lack of fusion occurs when the weld metal fails to fuse with the base metal. This discontinuity is critical in welding because proper fusion is necessary for the strength and integrity of the weld joint. In the case of lack of fusion, there is an insufficient bond between the two materials, which can lead to a significant reduction in joint strength. It can be caused by a variety of factors, including improper welding techniques, incorrect heat settings, or contamination on the surfaces that are to be welded. Understanding lack of fusion is essential for welders and inspectors, as it can compromise the safety and reliability of the final product. Inspecting for this type of discontinuity involves visual examinations and sometimes additional testing methods, so welders should be mindful of the importance of achieving good fusion in their welds.