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Overheard at a forge-in that changed how I harden springs
I was at a weekend hammer-in over near Springfield last month, and this older smith named Carl was talking to his apprentice. He said something like 'you gotta quench springs in oil that's been warmed up, not cold oil, or they'll always crack.' I always just used whatever oil was sitting around at shop temp, and I've had springs snap on me more times than I can count. He explained that cold oil shocks the steel too fast and creates stress fractures in thin sections. I tried it two days later with some 1095 leaf spring stock, heating the oil to about 130 degrees, and not a single crack. Now I'm rethinking everything I thought I knew about heat treating. Has anyone else noticed a big difference from warming their quench oil?
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felixlee1mo ago
Read somewhere that old-timers even tested oil temp with their bare elbow.
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Warmed my oil to 120F after a buddy's tip and haven't cracked a spring since.
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max4151mo ago
Nah, I've had fine results with cold oil for years, maybe your overheating is the real issue.
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