True surgical grade SS is not magnetic and will not adhere to a magnet very well at all.
"ss" screws we buy from the local hardware store are simply low grade chromium alloy plated iron alloy screws. Thats why they rust. (cheap thin layer of chromium plate)
"Does anyone know what the bulk material of steel is?"
Steel compositions vary widely. Steels in general have a lower carbon content than cast irons, and lower amounts of impurities like phosphorus and sulfur. Other alloying elements such as Boron, Chromium, Cobalt, Columbium (Niobium), Copper, Molybdenum, Nickel, Nitrogen, Selenium, Tantalum, Titanium, Tungsten, and Vanadium are added to improve corrosion, high temperature, and mechanical/machinability properties of steel.
The bulk material depends on the type of steel.
BEWARE there are thousands of types of steel in general, and 100's of types of stainless steel! LOL!!
So your qustion is basicly infinit LOL!!
BTW:
As stated already I wouldnt swet it one bit!!
Not even a blink! Even in a 29g I wouldnt swet it.
one small screw wont hurt squat.
as long as it dosent contain copper, "FOOK IT"!!!
LOL!!