Does a knight's armor rust

Answer 1

yes and it depends on when and how long they were used

Edit:

steel armour was often coated with paint to protect from rust, particularly on the inside. some types of armour, like Brigandine (made of many small plates attached to a fabric body) were tinned by dipping the plates in molten tin, to prevent rust. Other armours were covered to protect it. The classic "shining armour" however, required a lot of maintenance, and when stored away was often coated in a thin film of oil to protect it from rusting.

Answer 2

Yes, a knight's armor can rust if not properly maintained. Armor was typically made of steel, which is prone to rusting when exposed to moisture and humidity. Knights would often clean and oil their armor to prevent rust and maintain its effectiveness in battle.