What does the term "incomplete fusion" mean?

The term "incomplete fusion" refers to a defect where the weld metal does not adequately bond to the base metal. This can occur for various reasons, such as insufficient heat during the welding process, improper technique, or contamination at the joint. Incomplete fusion can lead to weak points in the weld, which may compromise the integrity and strength of the joint, making it a critical issue in welding performance qualifications. Ensuring complete fusion is essential for achieving strong, reliable welds that meet the necessary standards and specifications.