[hgs_notes]

Stress relieving your welds should not be needed. I'm a boiler inspector and do the required code inspections for boilers and pressure vessels. Because of the thickness of the materials your welding, it's not needed. It's usually only done on steel over 1" thick, and even then it depends on the pressure/temperature and type of use. Only high pressure boilers get stressed relieved using steel thinner than that. The most common method is heating the welds and weld effected zone. It's brought to a specific temp at a specific rate and held for a certain time, then slowly cooled again.

As far as magnafluxing goes, any machine shop that checks blocks and heads for cracks should have the equipment. You could do about as well using liquid die-penetrant on your own. All you need is the penetrant fluid, a cleaner, and developer spray. You just clean the weld area, paint on some ink, clean that off, then spray on the developer. Any cracks will immediately show up.

But to be honest, normal welding on thin mild steel will not usually create much cracking. It's a more common problem on thicker, harder alloys, or stainless. Magnaflux does not work on stainless BTW, not magnetic.

Cracks that happen on this type of welding, is not induced by the weld process. It's usually cyclical stresses from use afterwards. That's what is meant by "stress cracking" usually. If that happens, you grind it out and re-weld it. Maybe add in some bracing for that area to prevent a reoccurance. Problem solved.

Hope this aleviates some doubts.