Help with 5160 chopper

Revolverrodger

Revolverrodger

Joined
Jul 23, 2007
Messages
3,889
Hello Knifemakers,
I'm making my second knife (first was a small O1 camp knife)
This one is going to be a chopper made from stock removal (blade 9 inch 0.2 thickness)
I have looked online for HT protocols and have found this (from different sources):

1- Stress relieve by ramping to 1200ºF, hold 2 hours, furnace cool to 900ºF, cool in still air to room temperature
2- Preheat to 1200ºF for 7 minutes austenitize to 1525ºF for 10 min
3- Oil Edge Quench
4- Temper: twice at 425ºF / 2 hour

What is your opinion ?
Is this a good choice for a larger chopper ?
Thanks for the input !
 
I have not personally done this on a knife. However, from what I've read, which is a considerable amount, it's better to do a full quench and harden the whole blade. Then, after tempering in an oven, differentially temper the spine/tang with a torch and the edge sitting in water to keep it cool.
 
Change:
#3 to - Full quench in oil. (canola will work fine) Edge quenching for 5160 is improper.
#4 to - Temper at 425F twice for 1 hour each, water quench/cool between tempers.

Just for info purposes - there is no real need for the step#2 1200F pre-heat in 5160, and you can cool the blade from the stress relief in step #1 by water quenching from 900F. These are insignificant things, and what you have written will also work fine.
 
Thank you sir for the excellent info !

One problem I had with my previous knife was to put the final edge after I did the HT. It took hours with a lansky.
How do you guys do it ?

another question is: what kind of container do you use to quench a large chopper ? I have difficulty finding a large enough metal container for that.

I'm pretty excited to get this knife done.
 
For a large blade you want 2 or more gallons of quenchant.

These items can be had free if you check/look around, or bought for scrap from the junk yard:
Cut the top off an old oxygen/CO2/helium/etc tank
Cut the top off a 5 gallon soda tank
Cut the top off an old fire extinguisher
Tank from an old ice cream churn
Cut a hole in the top of an old beer keg
Cut the top off an old water 5 gallon heater tank
Note - welding tall and thin tanks to a car tire rim works very well. I keeps the tank from tipping over and raises up the tank a bit.


Other choices you might find at a flea market or surplus store:
4" shell casing from howitzer or ships gun
tall metal military storage/shipping canisters ( used for ammo, gun parts, mortar shells, and similar long things)


Best quench tank anyone could ask for:
Weld a 24" piece of 6" pipe to a 12X12" plate. If you don't trust the weld to be water tight, pour a 4 ounce bottle of thin CA in the tank and tilt the tank a bit while turning to let it seep into the joint. Stand up straight and let it sit for a few minutes and repeat the tilt and turn. Do that three or four times more over then next few hours. Let cure for a week. Fill with 2.5 gallons of Heatbath/Parks quench oil.
 
Why the 425 temper? Where are you getting the 5160? Forged or stock removal? Normally I forge any 5160 from large John Deere load control shafts, a very clean source of 5160 and after harding I temper to 350-365 deg.F. I've taken an edge quenched 6" hunter and bent to 90 deg. before the edge cracked heat treated this way. The hard edge went just above half way up the blade.

You can full quench and soft back draw and make a good knife. You can also edge quench and make a good knife. Both methods have there plusses and minuses, and I've done blades both ways. For me I like the control I get with an edge quench. Others may prefer a full quench with soft back draw. Try both and test and see which suits you and performs best for you.

My normal heat treat for 5160 is as follows.

Forging – Forge between 1625°F and 1400°F, and should not be forged in the lower red colors.
Post forging quenches – Heat to 1550°F and quench entire blade except for tang in room temperature Texaco type A quench. Hold the blade in the oil for at least 35 seconds. Repeat for a total of 3 quenches.
Normalize (stress relieve) - Heat to 1550°F and allow to cool below non magnetic and repeat twice more and allow to air cool to room temperature.
Low temp annealing – Set oven to heat blade to 988°F in one hour, hold 988°F for two hours, allow to cool in oven to room temperature, cycle twice more.
Hardening - Heat the steel to 1550°F and quench in 135-150 Deg.F. Texaco type A oil. Allow blade to cool to room temperature in oil, clean and repeat quench cycles twice more for a triple quench.
Tempering - Temper at 350-365°F for two hours, cool down slowly in oven, repeat twice more. Once done sharpen and test the edge with a brass rod, if the edge flexes your good, if it chips raise your tempering temps 25 deg. and temper again, repeat until the blade no longer chips.

This is what works for me in my shop. Best advice I can give is to try it and other heat treat recipes and test and see what works best for you and your methods.

As an aside, I use Texaco type A, it's a slow quench. A decent substitute is vet grade mineral oil, If I remember rite Ed Caffrey was using it at one time.
 
Will52100, can you explain why you anneal right before you harden? Are you grinding after normalizing?
Thanks.
 
I'm not doing a full anneal, just a low temp anneal that doesn't cause any grain growth and makes the blade very soft for grinding and drilling and filing and such.
 
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