Tried quenching a railroad spike knife in used motor oil. The result was not what I expected.

I was out of my usual quench oil last week and, in a pinch, grabbed some old 10W-40 from a jug in the garage. Figured it was just oil, right? Heated the spike to a bright orange, maybe 1500 degrees, and plunged it in. It didn't make that sharp hiss, it just sort of bubbled and smoked weirdly. After tempering, the blade was softer than butter. I could bend it with my hands. I think the additives in the motor oil, the detergents and stuff, messed up the carbon uptake completely. It was a total waste of a good afternoon. Has anyone else tried a weird quench medium and had it totally backfire? What did you use?

3 comments

3 Comments

kevin_schmidt971mo ago

Bend it with your hands" sounds like my first attempt at hardening a nail, which ended up as a fancy paperclip.

evan_dixon671mo ago

My buddy tried that once and ended up with a weirdly shaped coat hanger.

campbell.evan19d ago

So you actually tried to harden a nail by hand? What was the plan there, just heat it up with a lighter and hope for the best? I'm picturing you holding a red hot nail with pliers and trying to bend it into something useful. Did you even quench it in water or just let it cool on the counter? That paperclip result is honestly better than I'd expect.