Update: I've been quenching my leaf springs wrong for years

I was making a set of kitchen knives from old truck springs and kept getting hairline cracks along the edge. A guy at the local guild meet in Springfield watched me quench one and just said, 'You're putting it in the oil too hot, you can see the steam flash.' I never let the steel cool enough after forging before the quench. Has anyone else had this happen with 5160? What's your soak time before the oil bath?

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the_lee5mo ago

Yeah that steam flash is a dead giveaway. I had the same problem with 5160 until I started letting it cool to black heat, like you can't see any glow at all. My soak time is usually just a couple minutes once it hits critical, but getting the temp right before the quench is way more important.

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grace_stone5mo ago

That steam flash is the worst. Letting it go to black heat is the only thing that worked for me too. A cheap infrared thermometer helps a ton for checking the actual temp before the quench. Getting that wrong just ruins the whole piece.

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