Ss scorching and heat corrosion

[Alchemist75]

So I've noticed that the bottom of my ss boiler has gotten a bit scorched from repeated heating which has only occurred on the inside and isn't a big deal but I have noticed also the appearance of what might be heat corrosion spots on both the inside and outside of the bottom of the boiler. They look like darker, greyish spots and only occur where the direct heating happens. How much of a problem is this really? There's no apparent rust or major pitting. Is there a way to protect the steel from this or is it just the nature of the material?