I haven't had personal experience with laser marked barcodes being exposed to high temperatures; but, the mark should be OK. You might want to contact Dave Smith at Cerdec @ www.cerdecmark.com. They have exposed Cerdec laser marks to a variety of adverse conditions. Good Luck!
Good point AEF! You can get the particulars, including chemical resistance testing at: www.cerdecmark.com. The laser energy (heat) actual anneals the active pigment in the formula onto the stainless steel, creating a new alloy which is slightly raised on the SS surface.
Laser engraving using a laser sensitive pigment produces a permanent black mark on stainless steel, steel, and aluminum. It's very easy to use and can withstand very corrosive and other very unfriendily enviroments. You can see some examples at: www.custom-etched.com