Tried quenching in warm oil instead of cold, got a surprise
Switched my quench oil to a preheated 130 degree tank last Thursday and my leaf springs came out tougher but with a weird scale pattern I've never seen before, has anyone else run into that with used oil?
Preheating to 130 instead of room temp changes the whole cooling curve, so that scale is probably your used oil oxidizing faster at that heat. My first attempt at warm oil quenching gave me a blade that looked like it survived a house fire, so you're already ahead of me.