Clockwork,
Most of these questions can be answered by reading the stickies and researching other posts on the site. This is likely why you have not received a reply. The "what steel should I use?" question gets asked too often....
The experienced guys get tired of responding to it.
This is the near blind leading the blind, I have not yet played with stainless, but here is what I know from my reading and limited experience with carbon heat treat. I too am getting ready to use stainless, so here goes.
I would be very reluctant to use that pyrometer to heat treat stainless. Maybe someone with experience will chime in. You will be working right at its maximum. As you pointed out, most stainless requires temps in the 1900 to 1950 range. One small overshoot in your manual temp control and you risk overheating the thermocouple, especially with the long soak times required. An overshoot would probably ruin the TC and/or it may give false readings that you would be unaware of. $50 would get you a PID controller from eBay and a 2300 degree thermocouple from Auberins. You may even be able to use the PID to control your kiln. Holding within 10 to 15 manually seems difficult to me but I am using propane.
FYI, 10 to 15 degrees of variance is fine. Even the best ovens and forges vary by that much. There are always hot and cool spots that will vary that much even if the temp at the thermo remains constant. You need to go with high temp salts to get better control. That said we may get a reply contesting these statements.
Steel choice is up to you. 440c is the old standby and the one with the most heat treat knowledge in these forums. 154cm, and the CPM 30/35 series would also be good. Depends on your use. A kitchen knife would be better in 154cm or 440c since they are more stain resistant (with less edge retention?). I plan on using AEB-L for my first round of stainless chef knives and CPM 35sv for hunters/EDC's. The heat treats on all these steals are similar, but not the same. Pick one, research the heat treat and get experience with that before moving on to others.
Tempering should happen immediately after quench on any steal. It is possible for a blade to crack while it sits on the bench overnight after heat treat. Although I assume air hardening stainless steels are more forgiving than oil/water quenched steels. Either way, quenching stresses need to be removed as soon as possible so temper asap. For SS, if you are using cryo you want it in cryo as soon as possible. I do not remember if the temper should occur before the first cryo quench or between cryo 1 & 2. I do know that if you wait a few days, you've missed the window where cryo does much good. Ignore the last 3 sentences if you are not planning a cryo quench. My research shows cryo is not required but helps to get the most out of the steel. IE maximized hardness and better edge retention. Not sure yet if I will cryo my first rounds of stainless......
Looks like you are in Chicago, you should have lots of local metal suppliers for alum plate. Call a machine shop if you can't find a supplier who will talk to a hobbiest. If that fails, onlinemetals.com takes small orders and will have the plate in stock. That is where I got mine. Twas costly but I got tired of looking for scrap material.
Barry
