I guess that answer depends on what cartridge you are shooting, what powder is going through it, round count, what the firing schedule is, what the muzzle brake is made out of (aluminum vs steel), etc.
But I think most of the above is pretty academic and practically speaking you probably aren't going to wear out a muzzle brake in most situations.
By corrosion are you taking about the blueish residue that develops from carbon deposits? Or is there an actual material degradation you are observing? The former is easily solved through simple cleaning. The latter I guess the answer is "it depends".