actually, rust is aided by various environmental catalysts, such as water or salt. When carbon steel is rubbed on stainless steel, the iron molecules will print on the surface like lead from a pencil, and it will iniciate rust. I have done the test with a stainless steel cats water bowl.
A friend who works in water purification, (reverse osmosis) works with large pumps and stainless pipes and they don't even lift machinery with the usual forklift blades, without wood buffers. the tools all have to be stainless. for this reason, it starts rust. once started, rust never sleeps.
