1980s Soviet metallurgy isnt known for corrosion resistance. Now the whole skin is made of that metal. Don't forget the module we're talking about was built in

1980s Soviet metallurgy isnt known for corrosion resistance. Now the whole skin is made of that metal. Don't forget the module we're talking about was built in the 80s originally intended for MIR 2. It's been in service since 2000.