Tried quenching a leaf spring in used motor oil and it came out way too soft

I was working on a big cleaver last week and ran out of my usual quench oil. I had a gallon of old 10W-30 from my truck sitting in the garage and figured, why not? Heated the steel to a bright orange, maybe 1500 degrees, and dunked it in the used oil. The sizzle was normal but when I went to file test it, the edge just gouged. It was softer than mild steel. I think the problem was all the carbon and gunk in the dirty oil acted like an insulator, slowing the cool way down. My buddy Mike said he uses only new canola oil for his blades now. Has anyone else had a weird result with a substitute quenchant? What do you use when you're in a pinch?

2 comments

2 Comments

xena8864d ago

Man, used motor oil? That's a new one. I've heard of guys using old transmission fluid in a real pinch, but dirty oil is full of junk that'll mess with the heat pull for sure. Canola oil works because it's clean and consistent, but even then you gotta watch the flash point on bigger pieces. Next time maybe try preheating whatever oil you use to around 130 degrees, it helps a bit when you're stuck without the good stuff.

wren_walker624d ago

Tried that preheat trick @xena886 and it actually made a real difference last winter. My old peanut oil got too thick in the cold and warming it up first saved a batch of fries. Just gotta watch it doesn't get too hot before the food goes in.