This is the welded nut on the lower end. Failure occurred about ½ way inside the nut. Inspection would not have revealed an incipient problem. I suppose turning the nut would have broken the rod. The threads backed right out, no sign of stress near the threads.
Broken ends of the ¾” dia. stainless rod. Color is distorted by flash by crystalline structure is apparent.
No flash color here. Not much held the rod together! This failure was a long time in coming. The threads into the fitting are ugly but seemingly not affected by the fatigue.
The solid end fitting for the rod ends had no toggle, no way to dissipate sideways motion imparted by an anchor line rubbing on the stay, so there is no doubt fatigue caused the failure and water/salt corroded in the fatigue cracks. The top end fitting had no sign of stress.
The replacement was simple and inexpensive:
I hope this experience can keep somebody from the problem happening when it would lead to serious damage.