Re:MARCO'S TRUCK BUILD
Hello Dr. All SS has the ability to attract a magnet, it all depends on how it has handled or processed. I have a 6.00 scratch awl with a rare earth magnet on one end and it will stick to most SS. If the SS sheet was burned out with a Plasma cutter the burnt edge will most likely attract a magnet, the same with a SS wire weld, it will most likely attract a magnet. 304L is what I would use on most applications. If you will be doing work with chlorides " SALT " you would want to use 316L or H, 316 L is chloride resistant.
I built a SS Wet scrubber, 120 inches I.D. When the Code inspector was talking to me I dropped my $6.00 scratch awl and it stuck to my weld and he took a picture of it and showed it to the customer and the engineers who gave me the job, I almost lost my job because they said 316L cant attract a magnet but it did.
If your SS rusts it was probably in contact with Black Iron either in the mill, transportation S&H press brake or even a shear.
De-Rustit is a sulfuric acid paste or liquid that will stop the rust.