Originally Posted by
base2
Contrary to popular myth, stainless steel (or, corrosion resistant steel for the pedantic) does have a magnetic attraction. It is much weaker than high carbon for sure, but it is there nonetheless.
It's actually the amount of nickle in the mix that gives it, it's corrosion resistant properties. A metallurgist could give you a difinitive answer, but I always believed the attraction was in relation to how much iron the nickle displaced. More nickle meant less iron for the magnet to work on.
As always, the deeper you look, the more complicated it becomes.
I say go ahead and use the cables. Stainless cables, in my experience, last a lot longer & perform better than the zinc plated varieties.
Oooooh! A chance to dig up a bit of my old knowledge from the years I spent studying metallurgy (and which I've never used since).
The magnetic element of steel is a crystal called martensite. Higher quantities of alloying elements - Chromium and Nickel amongst others - the less martensite tends to form. So high alloy steels - such as is used to make spoons and forks - are not magnetic at all. However, it's the martensite which gives the steel its strength so high alloy steels are also rather soft. For this reason they aren't used to make kitchen knives, hence why these are magnetic. Once upon a time we didn't know how to make stainless steel which would also keep its edge which is why antique steel knives tend to rust. You obviously couldn't use a high alloy steel for brake cables either.
Off topic a bit, but the martensite also affects the malleability of steel. Small martensite crystals mean the steel is malleable - e.g. wrought iron. Big crystals make it brittle - e.g. cast iron. The crystal size can be controlled by several factors such as alloying elements and heat treatments, which is why with some steels like Reynolds 753, bike builders had to be specially trained to make frames from it. A bit of careless brazing could seriously affect the strength of the tubing.