The rust effect you have, which is good by the way, resembles that found on structures exposed to the sea or salt water. For normal corrosion I would suggest the colour Tin Bitz from Games Workshop, it's much darker and in keeping with the normal oxidation of iron/steel.
It's from my spares/bits box which probably pre-dates most people on this forum
It's back from a time when I was making a few 1/35 AFV kits (c1979) and came, iirc, from a M113 Command vehicle which had a table and a couple of these chairs. Might still have the other lurking around.