ericw93•2mo agoProlific Poster

Shoutout to the old guy at the scrap yard who told me to try quenching a piece of rebar in old motor oil.

I figured it would just smoke and stink, but it actually put a decent, tough skin on the metal, way better than my usual water quench for that junk steel. Has anyone else messed with weird quenchants like that and gotten a surprise?

4 comments

4 Comments

allen.anthony2mo ago

Honestly, the real surprise is that guy didn't also tell you to season it with bacon grease.

casey8182mo agoMost Upvoted

Yeah, old motor oil works shockingly well for high carbon stuff too, in my experience. The smoke is brutal, do it outside. I've had good luck with used transmission fluid for springs, it seems to cool a bit slower and cracks less.

lee182mo ago

My buddy swears by quenching in used ATF mixed with a little bit of brake fluid. Says it gives a crazy hard finish on tool steel without being brittle.

mark_chen6228d ago

Man, that combo is wild but it kinda makes sense... the ATF has detergents and the brake fluid is crazy hygroscopic, so it probably pulls heat out in a weird two-stage way. I've heard of guys adding a splash of acetone to old oil for the same reason, it changes the vapor phase. You get that hard shell but the core stays a bit tougher. The smell must be absolutely unholy though.

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