Login or register (free and only takes a few minutes) to participate in this question.
You will also have access to many other tools and opportunities designed for those who have language-related jobs (or are passionate about them). Participation is free and the site has a strict confidentiality policy.
I actually managed to track this down in the European standard EN 25817 (Arc-welded joints in steel), where it is indeed, as in Ernst, referred to as "undercut".
Thanks for your help! 4 KudoZ points were awarded for this answer