Hi all,
I'm battling a porosity problem that's either contamination, or an air leak AFAICT. I'll figure it out. Anyhow, while spending more time than I'd like with my grinder, I started to wonder about the nature of the problem. I know that one has to grind out all the porous metal before continuing to weld. It seems that if I don't grind out all the affected metal, then the porosity can just continue to eat into metal that wasn't affected before. IOW, if I apply heat to a small area that's porous it'll expand (indefinitely?) into the surrounding area.
What is it that causes porosity to "expand" (or does it just appear this way to me)? Is there something that happens to the metal during the process of becoming porous that changes its composition? Do the porosities that comes from different problems exhibit different characteristics?
Peter