Larry, all stainless is about 60% iron [might be why it's called steel?] with varying amounts of chromium, nickel and other elements, it's carbon content that varies to near zero - the difference in the 300 series is mainly carbon and nickel content, not a lot of difference in corrosion resistance, and no SS is totally corrosion proof

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot