You must protect A2 steel from oxygen by wrapping it in stainless steel heat treating wrap.If you buy any,get the kind that's good for higher temp.think the usual stuff is good for 1800 deg.I hope you have a pyrometer.Put a small pc. of brown paper into the envelope to burn up the air in it.Put the envelope in a cold electric furnace.Preheat to 1200 F.Hold for abt.15 minutes.Set the heat up to1750 F.Let it reach the temp.,and soak for a max.of 1 hour if the steel is 1" thick.30 minutes if 1/8" thick.The A2 will have a soft skin on it if you don't put it in the envelope.Have another oven ready when you pull the A2 out of the furnace.Other oven can be just a toaster oven,but you need to know what temperature it really is.I've used a high temp.thermometer from Brownell's,with a long shank on it,inserted through a 1/8" hole in the back of the toaster oven.DON'T trust the dial on the oven.Now,take the A2 out of the furnace,and cut the envelope open with some old scissors.Get the metal out as soon as possible.Dump it gently onto some soft firebrick surface,NOT METAL SURFACE.If it is a flat piece of metal,stand it up against a brick.Don't let it lay flat on the brick,or it will not cool quickly enough on one side,and may mot harden.Let it cool until you can barely hold it in your hand,and put it into the preheated 400 degree toaster oven.You can lay it on the metal rack inside the oven because it is already hot.Temper 2 hours for even 1/4" thick.If you don't get it into the second oven as explained,and let the metal get fully cooled,it won't be as good if the application is critical as to tool life.Otherwise,send it out to be heat treated!