What temperature is needed for heat treating? My wife's glass kiln goes up to 1500F.
Sorry, I meant to answer that in our email last week. The 1084 steel needs to be brought to non-magnetic, then a little higher for a few minutes. Yeah, kind of vague but someone with a forge and a little experience can quickly learn just by the color of the heated steel. Of course, a heat controlled forge or electric kiln simplifies that somewhat.
1084 needs about 1500° for maybe 5 minutes then quenched. 1095 is a bit more critical needing 1475° and a "soak" at that temp for about 10 minutes. So you'd be at about the upper limits of your wife's kiln and if you burn it out she's going to be mad.
Some people "soak" 1095 for as much as 30 minutes. Some simply look at any steel when using a forge or a charcoal fire and think, "That looks about right". SWAG method you may say, but it has been a very effective way of judging temperatures for centuries. Some people heat treat in a grill with a hair dryer "stoking" the fire hotter. Any of it needs to be brought just above non-magnetic. So you get varying opinions. Probably the more anal among knifemakers can overthink and over complicate. I use an oven because I can at least be consistent, and I happen to have one.
So steel has been annealed or made softer for cutting and profiling the blade and has to be heat treated to be useable. My understanding is the carbon needs the right temperature to go into solution and bond with the iron molecules which is the austentite stage, then quenched. Too hot and you start getting molecules clumped together and you get a steel with a very course grain that is weak and will break easily. The steel after quench is very hard and brittle and can even shatter like glass if dropped. After quenching it has to be tempered so as to not be brittle but also not too soft. You want it to bend without breaking or staying bent. That way, you don't get an edge that chips or bends but is flexible, as is the whole blade.
So different steels, depending on the carbon content and other alloys, differ slightly in the best heat treatment, and even among different batches of the same type of steel. Ideally, with each batch of steel one would do a test to determine best heat treatment for that batch, even making a blade and intentionally breaking it but I think that's a bit of overkill myself.
Frankly, I really am not that interested in the metallurgy of it all. I just want to know what temperatures work best for different steels and think it best to learn one or two steels and their characteristics. And there is a fair amount of latitude, more in 1085 than 1095.
Stainless is a whole 'nuther story.
All that and all you needed was "1500°".