I was in a surplus store and saw some huge drill bits for pennies. Has anyone ever forged a drill bit into a knife? What steel would they most likely be?

I would bet as hard as steel drill bits need to be that it would not be ideal for sharpening.

depending what the bit was made for could be a high carbon steel with Rockwell hardness up in the high 60-70 range. I guess you could Anneal it to soften it where it could be worked. but you would still wind up with a high carbon knife & they tend to rust easy. Plus you would have to beat the twist out of it , might make some interesting patterns like when they do cable Damascus. One of our knife makers that do there own forging would have a better answer