Yes, they get replaced with plastic. It happened to me as well (2011 aprc).
As someone said before, the ones they install now are plastic and Perfectly ok. Mine certainly never let me down since I had to replace.
Key is to really switch of the beast ASAP, when the manifold explodes as overheating affects worse parts that are more costly to run. In my case the thing burst actually not whilst riding (cooling is efficient then) but about a minute after the machine was turned off and the cooling system stopped. Restart is not an option, degrees rise very quick above 116 degrees...
Safe rides to all of you!
Ps: sorry this update is a little late.