Dave, I know all about martensite and other phases of steels. I am a mechanical engineer and my specialisation was in materials. Albeit a little while ago now.
I don't know what phase of steel is employed in bicycle chains. Sure, martensite is very hard but it is also very brittle. Surely tempering as you have described by the straw colour appearance would actually be desirable (and would have already been done?)
In any case, surely in the case of at least more expensive chains the hardness is supplied not by bulk properties but by nitriding?
Having said all the above, I know next to nothing about chain manufacture.