Spheroidize anneal question

[jdm61]

I am taking my first crack at a JS performance test knife. I am using Aldo's big 1084 and it is a 10 x 1 3/4 full tang blade. I just finished forging it this morning and put it in the Paragon at 1275 to spheroidize anneal it. My question is does this sub-critical anneal leave the steel soft enough to pass the bend test or do I need to do a full blown critcal anneal/normalizing regimen? I was planning to run it through one more time at 1275 after I rough grind the blade. Also, as I am using Parks #50 and this stell has around .89 carbon, should I run the tempering cycle up to 450 instead of 400?
Some may ask why I am using the 1084 instead of 5160. Well, it is the right size, I know the quality and the big reason is that I am not comfortable edge quenching W2. Otherwise I would use it as it bends like playdough when you anneal it and gets scary sharp and pretty darn tough when hardened.

 

[Mike Krall]

Joe,

I don't know if this will help... hope so... I'll read to you out of Heat Treaters Guide:

1090

Forging: Heat to 2100F. Do not forge below 1500F.
Normalizing: Heat to 1570F. Cool in still air.
Annealing: As is generally true for all high carbon steels, bar stock supplied by mills is in spheroidized condition. Annealed with structure of fine spheroidal carbides in ferrite matrix. When parts are machined from bars in this condition, no normalizing or annealing required. Forgings should always be normaliized. Anneal by heating to 1475F. Furnace cool to 1200F, at a rate not to exceed 50F per hour. From 1200F to ambient, cooling rate is not critical. This relatively simple annealing process will provide predominantly spheroidized structure, desired for subsequent heat treating or machining.
Hardening: Heat to 1475F. Carbonitriding and austempering are suitable processes. Quench in water or brine. Rounds under 0.25" diam. may be oil quenched for full hardness.
Tempering: As-quenched hardness of as high as 66 HRC. Hardness can be reduced by proper tempering.
Austempering: Responds well to austempering (bainitic hardening). Austenitize at 1475F. Quench in agitated molten salt bath at 600F. Hold for 2 hours. Cool in still air.

Recommended Processing Sequence for Forgings

* Forge
*Normalize
*Anneal
*Rough machine
*Semifinish machine
*Austenitize
*Quench
*Temper

Tempering chart shows, from starting hardness of 66 HRC... 64 HRC @ 300F, 62 HRC @ 450F, 59 HRC @ 600F

Because you have an oven, the listed spheroidize anneal can be done. My understanding is spheroidize anneals are done on a quenched blade. So you know, my understanding of this stuff doesn't turn out to be exactly right sometimes, but I've been quenching after normalizing then doing a different method of spheroidizing in my forge.

Mike

 

[mete]

There are two types of 'annealing'. One is to austenitize then slowly cool [in furnace or ashes etc] .This gives a somewhat coarser spheroidize structure. The second way is to harden to martensite then temper at about 1200 F. This gives a finer spheroidized structure and is called "sub-critical anneal".

 

[Kevin R. Cashen]

If you want to pass the bend test, the spheroidal anneal will beat any other hands down. The bend test is all about ductility, and pearlite has nothing on spheroidal carbide for ductility, the lammelar structure of pearlite still has the posibility of fracture, spheroidized steel is virtually impossible to break without adding defects to facilitate it, it just bends like putty. To all of this you can also add that spheroidizing will not mess with any grain size you set up in the normalizing stage, so you can maintain your nice fine condition. I am not saying a putty like blade is good for a real knife, but it is great if you want it to bend

 

[jdm61]

If you want to pass the bend test, the spheroidal anneal will beat any other hands down. The bend test is all about ductility, and pearlite has nothing on spheroidal carbide for ductility, the lammelar structure of pearlite still has the posibility of fracture, spheroidized steel is virtually impossible to break without adding defects to facilitate it, it just bends like putty. To all of this you can also add that spheroidizing will not mess with any grain size you set up in the normalizing stage, so you can maintain your nice fine condition. I am not saying a putty like blade is good for a real knife, but it is great if you want it to bend

Thanks. Kevin. Follow up question. I did not quench before throwing the blade in the oven a 1275. I just run the oven at temp for two hours and then let it cool slowly. Is that incorrect?

 

[Larrin]

Martensite allows for much faster spheroidizing, I believe Kevin recommends quenching first.

 

[jdm61]

I spheroidize anealed one balde that I subsequnetly messed up, so it never got quenched. I did the old bend test on it and it was pretty darn soft. But thanks for the info. I have the first crack at the JS test blade rough ground and "rounded off" No plunge cuts, no sharp edges, etc.

 

[delbert ealy]

You will get a finer grain structure if you quench before you spheriodize.
When I spherodize O-1 or L-6, I normalize and allow to air cool unless I'm in a hurry in which case I quench. Then I set the oven for 1375 and hold for 1 hr, then I drop it 40 deg per hour until I hit 850 then the oven shuts off. Works great for both steels.
Thanks,
Del