Mild Steel (either hot rolled or colled rolled) is relatively inexpensive and cuts ‘like butter’ making it a great option for screens with a dense pattern.
Mild steel screens are more often used for interior screens in shop and restaurant fit outs or as balustrading where a heavier screen is required and/or environmental elements aren’t of concern.
To use mild steel in exterior screens they would need to be hotdipped galvanised prior to powder coating.