[David]

I guess notch sensitive was not the right wording. I just removed six broken dilivar studs plus the 6 unbroken ones. One of them had severe cracks and was probably days away from failing. Since this thread was started I've tried to find out what the problem is with them. I analyzed the material of one of the broken studs at work. I didn't write down the material composition. I used a portable nuclear analyzer so even if I had written them down they still would be a little off. I remember them to be about 14% nickel, 4% chrome, 2% moly, 1% vanadium, and the balance iron (this particular analyzer doesn't read carbon). I could find no other common (or uncommon) material that matches this composition. I'm not a metalurgist, but my guess is that the nickel was added to increase the thermal expansion (I don't have the table in front of me so I could be off) and there is not enough chrome to fiend off stress corrosion cracked (SCC). SCC is caused when you have a material that is highly stressed, like a stretched bolt, with significant heat and some type of corrisive which may just be humid air. There is obviously a lot more to this issue and I'm not finished researching it. I'll post back to this thread as I learn more.