Water vapor in the form of humidity is sufficient to initiate the rusting process. Most questions along this line are addressed on this page: https://van.phys

Water vapor in the form of humidity is sufficient to initiate the rusting process. Most questions along this line are addressed on this page: https://van.physics.illinois.edu/qa/listing.php?id=485 https://van.physics.illinois.edu/qa/listing.php?id=485 Note that if you try to avoid the formation of rust by submerging your steel in water, thinking that will remove the oxidative air component, you run into corrosion issues unless you are submerging in a tank of constantly refreshed distilled water.