What happend.

JTknives

JTknives

Joined
Jun 11, 2006
Messages
8,651
well saterday i was working with my 5160 from burton. got the blade done and went to heat treat. fired up the forge and brought blade up to temp. tested with magnet was good no stick so put it back in for few more sec and quenched. then cleaned and tempered to 400. but today i was testing the blade and it looks like just the back half will skate a file and the frount of the blade seames soft. i did not remove very much material but it did not seam to get harder. this is the first time working with 5160.
 
The Currie Point (Non-magnetic ) is only about 1414 degrees F. The Heat Treater's Guide shows that 5160 is supposed to be Austenitized at 1525 degrees F before quenching in oil. Sounds like you may have underheated your steel by more than 100 degrees. If the spine is harder than the edge, I would guess that either the blade wasn't heated evenly, or you have decarb on the edge.
 
Just a swag, but I think uneven heat, not enough heat, it may have cooled too much before you got it in the quench, since it sounds like it wasn't hot enough to start with, and 5160 needs some soak time to reach it's best potential.
 
Before you go back and redo the HT, sand the edge down completely. It may have a good layer of decarb. Most folks who HT by "a little more than non-magnetic" overshoot by a lot,but it is possible that the temp was too low. I'd bet that there is hard steel under the soft stuff.
Stacy
 
its funny because the back half is hard but shows no heat but the frount half looks like i could have over heated it and thats the section thats not hard. what is the quenching speed of 5160. i just got a gallon of minerial oil and im going to try that as i have not picked up my Type A oil yet. but when i do i want to keep it in good condition as i am onley getting 1gal. i did the quench with veg oil as thats all i had at the time. i know i know use good oil, but i was facing north :D. thanks
 
JT, Didn't look it up, but I'm pretty sure the quenching speed of 5160 is pretty slow....pretty much like 52100, somewhere around 3-4 secs. Doesn't sound like a quenchant problem....sounds like uneven heat and not enough of it.
- Mitch
 
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