Apologies for re-awakening this debate, but I think it deserves it. I seem to be on a 1-person quest to reduce the amount of artistic rusting we see on armoured vehicle models.
Armour plate is a debate in itself, but is related. Armour plate alloys will contain substances such as manganese and nickel which inhibit - but not prevent - rusting. The accretion of carbon to the outer face from the heat treatment process also inhibits rusting. And it wears to a dull dark brown colour, not bright metal. I see too many "in service" models that are rusted like 30-year range wrecks.
Tracks are a similar situation. By the start of WW2 most track alloys for all-metal tracks contained manganese for durability. This also inhibits rust very well, but does not prevent it and the rust tends to have a greyish patina: certainly not orange. And the metal isn't a silvery colour, nor does it wear to a silvery or graphite colour. It is a goldy-brown colour for which I have yet to find an adequate match or mix. I'm not sure the Russians or French used much if any manganese in their tracks. The UK, US and Germany certainly did, although German use may have reduced or stopped later in the war.
Post-war, with the rise of rubber-padded tracks the metal parts of the links had less reason to contain much if any manganese and post-war tracks do seem to exhibit more conventional rusting. Russia has stuck with all-metal tracks, the manganese content of which is uncertain.
This is a British manganese track as fitted to Tortoise: big links so the effect is more visible. Note the colour of the contact areas on the spuds/cleats.
This is my attempt at depicting it.
This is an all-metal M4 track, T62 type. Also manganses steel, at least for the cleats.
This is an Elefant track, which appears to be hot oil blackened and does show some orangey rust, implying not manganese.
KV-1 track. Manganese - note wear point colour
A9 and A10 Cruiser track. Manganese
102 year old WW1 MkIV track. Not manganese, but not much rust either. These actually look like they've been subjected to face hardening like armour plate.
LVT-4 tracks
T-55 tracks. I would say low manganese, or none. Note orangey rust. But with no manganese they would only last a few hundred miles.