Comparing O1 and 1084

Willie71

Willie71

Warren J. Krywko
Joined
Feb 23, 2013
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I just finished up 2 knives (a little more polishing on the handles, but basically done) and I note the O1 knife holds a keener edge. Both get shaving sharp quite easily, and the edge geometry is pretty much identical (the O1 is little wider under the edge but only .002" or so.) Now I understand 1084 makes a perfectly fine knife, so I want to make sure I didn't mess anything up in HT. I aimed for Rc61 on the O1, and Rc 59/60 on the 1084. I have no way to test, so these numbers are assuming the HT went as planned. Both are bird and trout knives. What do the more experienced makers note between the two steels?
 
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01 will hold an edge longer than 1084.

Get ya a hardness tester. I just got one, wish I'd have done it 20 years ago!
 
But will O1 get sharper than 1084? I sharpened them both at the same time with the same equipment, and the same technique. The 1084 seems courser, or less refined at the edge than the O1. I plan to get a tester, but its a big startup expense, and lean towards a 2x72 first, then the tester.
 
Sharp is mostly dependent on grain size. 01 contains vanadium which promotes fine grain, while also adding carbides. PG 01 usually comes ready to go as is. 1084 may need heat cycling to refine it's grain.
 
What LRB said, sharpness has a whole lot to do with grain size. Your 01 probably started with finer grain when you heat treated both. But 1084 can be cycled to refine the grain as such.

I just paid $250 for a tester, deals are out there. ;)
 
I've been using 1084 for a couple of years now and only used O1 for the past year. So far I have had much better results from the O1 than 1084 with sharpness and edge holding.

My typical test is 500 cuts on cardboard. O1 will easily shave after but the 1084 stopped shaving after 400 cuts. It could be my heat treat method on 1084, but since everyone brags about how easily it is to heat treat, I'm thinking it has more to do with the steel than the HT process.
 
Thank you. I will keep my eye out for a tester. I previously priced them out at about $1100.00 shipped to Canada. Both steels were normalized prior to heat treat, but nothing special like a triple normalizing or 1200f subcritical anneal. I followed the temp guide at Kevin Cashen's site. (propane forge, used a flux on the O1 to prevent massive decarb with the soak.) I was originally worried the O1 was too cool going into quench, but the steel is performing beautifully. I am using a Maxima fast oil for quenching. I don't know the specific number off hand, but from what I understand, its a step faster than parks 50. I was worried with the O1 as it was a bit thin going into HT, .020" at the edge, and the edge rolled right out of tempering. Once I ground past the decarb, no more rolling, and amazing slicing. After watching Nick's video, I sliced some 9oz leather. The O1 was like butter through the leather. The 1084 cut without sawing, but not as easily. I stropped both blades, and the O1 shaves effortlessly. The 1084 is now as sharp as the O1 was before stropping. I may have just fluked out and got a near perfect HT with the O1.

In future, I will do a series of grain refining cycles on the 1084. This is the most likely difference in the steel performance.
 
O1 does not always, or even typically as far as I know, contain vanadium. Even if/when it does, the relatively small amount of V (as "much" as .30%, according to some reports) is there for its grain-refining characteristics and probably forms very few carbides. Similarly, the small amounts of chromium and manganese are there mainly to improve its deep-hardening.

1084 reportedly has a similar amount of manganese, and if you're buying it from Aldo it also has a touch of vanadium. The main difference between the two chemically is the addition of chrome, and perhaps carbon levels (around .8-.9 % for 1084, nominally .95% for O1).

It is certainly interesting how two alloys that are so very similar have actual notable differences in edge-holding and corrosion-resistance. (O1 will rust if you glance at it funny... you have to actually stare at 1084 for a while ;) )
 
I got the O1 from metal superstore (the only knife appropriate steel they have. I went in there after I decided scrap steel was too much of a crap shoot.) The rest of the steel I have comes from Canadian Knifemeker.
 
jawilder said:
I've been using 1084 for a couple of years now and only used O1 for the past year. So far I have had much better results from the O1 than 1084 with sharpness and edge holding.

My typical test is 500 cuts on cardboard. O1 will easily shave after but the 1084 stopped shaving after 400 cuts. It could be my heat treat method on 1084, but since everyone brags about how easily it is to heat treat, I'm thinking it has more to do with the steel than the HT process.
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Ease of Heat treatment is a relative thing. 1084 being a eutechtoid steel, everything important that needs to goes into solution pretty much when you hit the austentizing temperature, soak time is not necessary (you do not want to solution the vanadium carbides because if you do you unpin your grain boundaries) so 1084 is recommended for heat treating with primitive equipment. As long as you bring it up to decoalescence and quench in fast oil you will harden it. You can really fine tune it (especially Aldo's with the vanadium) with more sophisticated equipment and process control you can significantly improve your results. OTOH O-1 with all the goodies in it requires good temp control and a soak time at temperature. It is much more forgiving about quench oil speed but has some interesting properties that can trip up the unwary. One of the biggest issues seems to be precipitating lamellar pearlite if cooled too slowly or heated then worked at or around the pearlite nose. O-1 is designed for making industrial cutting tools so it can keep an edge really well and is moderately abrasion resistant but my opinion is that with the carbide formers in the mix it will not get quite as microscopically fine an edge as optimized 1084v or 1095 but what you put there will last longer.

-Page
 
james terrio said:
O1 does not always, or even typically as far as I know, contain vanadium. Even if/when it does, the relatively small amount of V (as "much" as .30%, according to some reports) is there for its grain-refining characteristics and probably forms very few carbides. Similarly, the small amounts of chromium and manganese are there mainly to improve its deep-hardening. ;) )
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Yes, 01 does typically contain vanadium. It is unusual to find 01 without it, if at all.
 
I have only run across two suppliers that did not list vanadium, and I suspect an oversight in both cases. Although, if not listed, I buy elsewhere.
 
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