We published an Update, where we have analysed the case further. It is published in our printed club magazin (in german). See page 14

https://bergsteigerbund.de/wp-content/uploads/20 25/12/SBB-Ma gazin_2025_11_v4_web.pdf (odstranit mezeru)

Summery:
1) The ringbolts were made by german friends of Karel Belina.

2) actually they are stainless and oversized and would be solid, if there wasn't the welding... So no "junk" was intentionally installed.

3) The reason for the cracks are different materials, where one is not really suitable for welding. It hardens, during heatingprocess (welding) and gets brittle. A few load cycles (maybe falls, maybe just hits with a hammer, while installing) are enough to let little cracks grow further...

Our first guess was Stress Corrosion Cracking (SCC) like dicribed in the comment above. But it may not be the case here, because it mostly needs chloride as a corrosive medium. This type is often seen on stainless steel bolts close to the ocean (Sicily, Sardinia, Thailand,...) but not in our sandstone areas.

Report findings as described above and keep your eyes open!

Climb save
Frank (leader technical commission, SBB)