Oil Quenchant for Heat Treating

[ApprenticeMan]

Originally Posted by TarAlderion

Sandpile is right A.M. If you quench 5160 in water you will crack it, unless you are extremly lucky, but in most cases it will crack. And if it doesnt crack it will be brittle beyond any use. You must use oil.

And, if you harden a blade and it does not need tempering afterwards that means it did not harden in the first place. You must always temper or your blade will not be of any service and will break with the least amount of stress.

When I get some more $$ I might check out that soybean oil, sounds good.

Tar Alderion

Originally Posted by sandpile

A.M. carbon steels irregardless of quenchant have to be drawn back to the hardness you want. If left completely hard, they will break like glass went dropped.

Chuck

P.S- Don't put 5160 in water for a quenchant.Grin.

I have never had a problem, I use water for most everything, and i still have a center punch that has been used and abused that I hardened and tempered in water, last year, it is 5160, and it shows no cracks, no nothing. If you want to know the trick to it let me know.

[ApprenticeMan]

And that punch has been abused, not abused abused, but let me just say i hot punch EVERYTHING, and use it as a drift as well too. I have flattened the tip more than once, re ground the tip and used it again, and like I said, it shows no cracks, no nothing. But it could also be my punching technique, I just drive the punch right through, then knock off the little slug.

[TarAlderion]

Well, A.M. as for your punch and water hardening. If your water quenchant was warm/hot that could have slowed the quench enough not to cause cracking, or if you quenched below the critical. Or you were just fortunate not to have a crack form. Plus you mentioned tempering, if you tempered enough (500 F + or when it starts to turn blue) the punch should work just fine. Plus you said you hot punch, everytime you punch you heat up the punch itself, and if it gets hot enough you temper it. If you have flattened the tip multiple times that indicates that the heat treatment has gone due to lots of heat (either in the initial tempering or through its life of punching.)

I have experimented with 5160 and water quenching a few times and the first time I quenched a section of it from the critical, I got a crack. The rest of it was brittle enough to break over the edge of the anvil. I also have tried heating the water and then quenching, this tended to reduce the tendency for cracking but it did not help the brittleness much, which means a good tempering is needed. But for the most part, I find its best just to use the oil and not have to worry.

Tar Alderion

[ApprenticeMan]

Oh cool. Yeah my water is pretty warm all the time, except if I get to the shop in the early morning. It's a small little bucket, so a few quenches heats it up pretty quick.