What is a common discontinuity that may occur in welded fabrications?

Lack of fusion occurs when the weld metal does not adequately bond to the base metal or to itself. This discontinuity can happen due to improper welding technique, poor joint preparation, or insufficient heat. Inadequate heat may not melt the base material sufficiently, leading to incomplete fusion at the weld interface.

Welds need to be thoroughly inspected to ensure that they meet quality standards, as lack of fusion can compromise the integrity and strength of a welded structure. Unlike other issues such as porosity, which is trapped gas in the weld bead, or inclusions, which involve foreign materials becoming part of the weld, lack of fusion specifically relates to the failure to achieve a solid bond. Cracking is another critical issue in welded fabrics but arises from stress and thermal contraction rather than fusion issues. Understanding these characteristics is essential for producing reliable and sturdy welds in various fabrication processes.