Thanks for the reply guys. Are there any Titleist reps out there that want to chime in?

Hi Dave,

Typically steel shafts don't fatigue unless they are repeatedly stressed past their yield point or they have been stored in less than ideal conditions. I would encourage you to closely examine the shafts in your DCI irons to ensure their structural integrity, and seek the advice of your local PGA Professional if you have any doubts.

Graphite shafts, however, are different because they don't have a yield point like steel. If they are overstressed, they crack. Generally that means an immediate, obvious break in half. It may survive another shot or two before full failure, but a player will always feel something different during impact.

Hope this helps.

Thanks for all that replied. clears it up for me.