Power supplies are usually plated or coated recycled "chinesium" steel. This is because it's incredibly cheap and has a half decent EMC outcome for the price. One little nick in the coating or plating and that's it though. Really they could use other materials such as cast aluminium, brass or copper but they are orders of magnitude more expensive.
If you look at some of the older electronic test equipment which was made with much higher standard materials it's not uncommon to find something that has been in a damp shed for three decades and powers up just fine after the dead spiders have been removed and the mould cleaned off. BUT at the time of manufacture they cost more than a mid-range car.
If you look at some of the older electronic test equipment which was made with much higher standard materials it's not uncommon to find something that has been in a damp shed for three decades and powers up just fine after the dead spiders have been removed and the mould cleaned off. BUT at the time of manufacture they cost more than a mid-range car.