Aluminum, magnesium and austenitic stainless steel are also non-magnetic. But they also have worse strenght/weight ratio than titanium. All of the above are di

Aluminum, magnesium and austenitic stainless steel are also non-magnetic. But they also have worse strenght/weight ratio than titanium. All of the above are difficult to weld. This increasest the cost, which means fewer subs. So current submarines are made out of low alloy steel.