You are wasting your time on mild steel, you need something with a higher carbon content.
This^^^
Heat treating is a fine art at the best of time but to make much headway you need a steel with a higher carbon content and an oven that can control the temperature to within a degree or so.
This will sound daft (although it's been mentioned above) you need something soft to protect attack specifically against grinder attack. Aluminium would hold up longer than mild steel, stainless alloys also do well (nickel stainless alloys especially) and stainless alloys are very resistant to heat which is why they're used in high temp applications (you can't wash many stainless steels with an oxy propane set because you can't get them hot enough)
As for hard facing you'll do well to find something much better than stellite. We used to do a lot of hard facing for steam valve components. How you weld it is another question but but I've spent enough trying to machine it in the past, pot hard doesn't come close! We've used ultimet too which is similarly hard but any cobalt or tungsten based rod/filler wire would have the same effect.