Quote Originally Posted by DanCom View Post
Nick,

I work with stainless and it has a prescribed "soak" temperature and time to hold at to ensure the carbon is in solution. For 1084, I get it to critical temp, wait a couple of minutes and then quench. For O1, I hold at critical temp for 10 minutes, then quench. Each steel has its own recipe if you will. Steel manufacturers like Sandvik and Crucible prescribe soak times based in the thickness of the steel. E.g. hold at x temperature for y minutes per cm of of thickness. This is because the outside of the steel heats faster than the inside. Another step in the heat treatment process is "equalization." This is a rest period to ensure uniform temperature in the piece. As my oven ramps fairly slow, and 'am usually using thin steel (3mm or less), I often skip the equalization step as the steel is roughly the same temperature as the air in the oven. A fast heating oven will have the interior temperature rising faster than the steel. Fast ramping and thick steel will require longer equalization and soak periods.

There's plenty of room for experimentation as each oven will behave in a slightly different way. Placement of the thermocouple will impact the readings somewhat. I place my thermocouple through the bottom as close as possible to the blade rack. Really what I want is the temperature of the steel and not the temperature of the air in the top of the oven. Make sense?

Also, run the Autotune on the controller if you haven't already.

Cheers,

Dan
Thanks so much Dan. So i have worked out that my reading is about 100C out and realised that the tip of my probe was in perfect line with the elements which cant be good. Thanks so much for all the good advice and the best blog. I made your belt grinder by the way. Very grateful for your sharing so much know how.