Cast Iron to ABS - exterior of cast iron not smooth - how to stop leak at coupling?
One of these ironic things? ("American" Valve - Made in Taiwan...)


You should probably try to smooth the pipe out more - a lot can be done with a narrow strip of coarse sandpaper, wrapped around the pipe so you can "saw" it back and forth. You can also try really cranking on the hose clamps - if you're only using a screwdriver, you haven't really hit what they can do (but you have to maintain some sense of proportion once you switch to using a socket and ratchet on them, or you'll find the breaking point.)

For sheer desperation, I'm not sure if silicone or beeswax (from a toilet seal ring, of course) would be the better desperation move. With kitchen waste it could get too hot for beeswax.