rust
 

this is kinda a dumb question ,but i just got back in to the hobby and i started going through a lot of my old cars i sotered them in a up stairs bed room its kinda cold in there in the winter time but i leave the door open most of the time . anyways as i was looking a my old cars the cvds and black steel screws rusted on them. what causes this

Moisture.

but i had it in my house i didnt think that it would do that. they sat for a long time though. like two years.

is my house to damp or is it just because its steel and some of the coating has worn off

There is moisture in the air... Humidity. "thumbsup"

just change the screws to stainless they never rust

stainless will corrode. it just takes a really long time. dissimilar metals, when in contact, create very small electrical currents that cause the rust. also, if you do any machine work on the stainless with a non-stainless tool, it will corrode in the machined areas. that is what they told me in college, anyway. and the foglight brackets i made from stainless for my old car rusted where i ground the edges round.

rash

unless they are vaccum sealed in a air tight bag it will rust

The heat/cool cycles from season to season will cause condensation. Drier climates will not be as bad, but it still happens.