From Longman Dictionary of Contemporary Englishrust away phrasal verbHCMto be gradually destroyed by rust The blades of the swords have rusted away. → rust→ See Verb table
Examples from the Corpus
rust away• But under the ground they were half rusted away.• Even I could see it was rusting away.• No-one had noticed that while they huddled together the armour-plating had rusted away.• Now, the Berlin Wall has fallen and the barbed wire rusts away.• The old mills just stood there, quiet, closed, rusting away.• These are rarely found complete as the blades are generally made of iron and have therefore rusted away.• His old heart was rusting away in there.• Cars and motorcycles had been confiscated or were rusting away useless for lack of parts. 