We always have something in the rock trap. It's usually one a couple times per season we'll be forced to clean it because there is something in it which is banging against the bars and won't stop.

Far as I'm concerned, chipping is not an issue on either the chrome or the hardfacing.

We broke one of the very first chrome bars we ever put in...incidentally also one of the very first Loewen bars we put in....literally on the first hopper after they were installed. They replaced it. There was a sizable hedge post in the cylinder. Neighbors ate a field cultivator shank on one of their old 8820's one year. Busted several bars and pretty well destroyed the spiders they bolt do. I don't know if they were chrome or not, but I imagine they most likely were.

Regarding warping during hardfacing.  First, there shouldn't be that much heat involved in hard facing one edge of a 2x3/8 strip in a concave, second, they are welded before they are ground, so once they are ground true it really doesn't much matter if they did warp when they were being welded.