Shoutout to the guy who told me to quench in warm oil instead of cold

I was out in my garage shop last month and cracked a blade right down the middle because I used cold oil from the can... switched to preheating it to 120° and haven't had a crack since. Has anyone else messed up a heat treat from skipping that step?

3 comments

3 Comments

phoenix_singh256d ago

Oh man, I gotta disagree a little! I've been quenching in cold oil for years and it works fine for me as long as I pull the blade out before it's totally cool to room temp. That extra thermal shock from cold oil (you know, the violent kind) can actually help with hardness in some steels, or so I've found.

logan_wood6d ago

Warm oil is the way. Cold quench is just asking for trouble with thicker blades.

phoenix_grant6d ago

135 degrees is actually my sweet spot for 1080 steel, I tested it with a thermometer last year. The problem with cold oil is you get that uneven cooling where the edge zips past the nose and the spine is still hot, that mismatch is what cracks blades. Preheating slows the quench just enough to let the whole blade transform at the same rate, especially on thicker stock like quarter inch. Plus warm oil flows a lot better so you don't get those vapor jackets that cause soft spots. I stopped guessing after I ruined a six hour damascus billet, never again.