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Old timer told me to quench in warmed oil, I didn't listen | Blacksmiths - Free To Speak

Old timer told me to quench in warmed oil, I didn't listen

Been forging for about 2 years now, mostly just hooks and brackets for local folks in Ohio. This guy Bill who's been smithing since the 70s kept telling me to warm my oil to at least 120 before quenching anything thicker than 1/4 inch. I figured it was just old man caution and cold-quenched a 3/8 inch leaf spring I was trying to make a knife out of. Cracked right down the middle on the second quench. Stupid waste of 4 hours of work. Anyone else learn this lesson the hard way or was I just being too stubborn?

2 comments

2 Comments

lily_torres311mo ago

...and of course I learned it the exact same way except with a railroad spike that I spent way too long on. My oil was room temp, maybe 65 degrees, and I figured "hey it's fine, Bill's just being dramatic." Nope. Cracked so loud I thought my anvil broke. Now I keep a thermometer in my oil bucket and warm it on a hot plate like a fancy chef. The science makes sense though, warm oil lets the heat transfer more evenly so the steel doesn't freak out and split. Wish I wasn't so hard headed about it, but hey at least Bill got to say "told you so" with a big grin.

davidkim1mo ago

That story about the thermometer and hot plate is exactly what I ended up doing after my own failure. It feels silly at first, treating a bucket of oil like you're cooking a steak, but honestly it saves so much headache. The way I see it now, cold oil creates that sudden shock on the surface while the inside is still hot, and that difference is what causes the crack. Warm oil slows things down just enough so the whole piece cools at a similar rate. I also learned to keep my oil a little warm even for smaller stuff, since it never hurts and makes the process more predictable. Bill probably got a good laugh out of watching me learn the hard way too, but now I just nod and say "yep, you were right.