ORIGINAL: bbbair
Before you run around trying to find a hardened rod - Why don't you harden your existing ones yourself?
I have been hardening my landing gears for years, it is a simple matter and I don't see why it wouldn't work for the threaded rods...
Line a cookie sheet with tin foil (This keeps the wife happy), place your rods on the foil and put the entire affair in the oven. Turn the oven on and set the temperature to 450 degrees farenheit, cook for 30 minutes and then turn the oven off, allow the rods to cool slowly.
Check for the strength that you were looking for.
Bruce, I'm amazed that your technique works -- it sounds more like a good way to anneal the rods, although the temp is pretty low.
Normally, a quickie way to harden ferritic alloys is to heat them to a dull red & quench them in a carbon-based coolant (oil).
Another way is to put the parts into powered carbon (or cover them with powered carbon) & heat them up to a specific temp (a lot more than 450 F) & then cool at a controlled rate.
I'll have to try your method.