Has anyone used 416 stainless steel. A company in Florida makes large water pumps, they use 416 for the shafts. I know 416 is a free machining stainless but will it rust?

I've heard that it is not as corrosion resistant as 304 or 316, but in pump service, immaculate appearance may not be uppermost in desirable features. The more corrosion resistant grades like 304 or 316 are a bit finicky when it comes time to push bearings or wear sleeves on and off the shafts.Often, they will gall extremely badly, ruining the shaft on the first overhaul.

416 has improved corrosion resistance if it is heat treated, too. It does not get super hard, maybe 35Rc or so, but it does machine nice in the hardened condition.

Thanks for the quick reply.

Just to add you can surface harden 416 to 60 Rc by using nitriding.

Yes 416 cuts real well, and it WILL rust slightly but no where near as bad as plain steel, the most I have seen is a light surface rust.