[ATalley]

Im not sure how others feel about this, but Ive been taught to put the knife in the oven at room temp and then run up to your target temp. Ive not heard of placing a cold knife blank in a hot oven thats at temp and letting it catch up during 'soak time', seems as if that would invite warpage and other problems. The steel isn't having enough time to get into solution and that could result in problems like what you are experiencing.

Its been explained to me that a soak time is when the environment inside the oven reaches the target temp and you the oven to stay at that temp for an amount of time to allow the carbon, iron and any other alloys in the steel to flow into solution and create solid bonds between the atoms. (10** series steels are only carbon and iron= so a long soak time isn't required) the equation Ive heard is 1 hour per inch. So if you have a 1/4" thick piece of steel the ideal soak time is 15 minutes.

Cant say as I've seen the embedded/etched/engraved circles before. Im sure there is a wise guru on here who may be able to advise.

The third photo looks like a boil youd get during the quench. if you are not moving the knife, or circulation the oil enough during the quench, the fluid near the knife takes too much heat and boils which create a bubble of gas and that part of the knife its touching doesn't get cooled properly resulting in that little circle in the steel.

Jut $.02 from this guy...good luck!

And Happy New Year! Auld Lang Syne!