O1 heat treat problem

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spareparts

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May 12, 2010
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I'm a stock removal guy. I've been using Aldo's 1084 with good success. I decided to try some O1 because I can pick it up locally. Using 1/8" O1 I made 6 small utility/paring knives and a couple of 10" and a 6" chef knives from O1 with no problems and all pass the file test. I normalize once or twice, then raise to non-magnetic, let soak for about a min. and quench in heated canola oil with a little motor oil used just to top off my quench tank.

I used the same procedure over the weekend on 6 more O1 1/8" steel chef knives ranging from 6" to 10". One warped and all failed the file test. I went ahead and tempered them at 400 F for two 2 hour cycles just to see if that would effect anything. Which it didn't

So tonight I decided to re-normalize them three times, raise to non-magnetic, soak for a min or two, then quench. Sill can't pass the file test. And now at this point I have several blades showing noticeable warppage. Since the forge was hot I figured one more try on another blade and still failed. At this point I sacrificed one of them and broke the blade to see what was going on inside; creamy dull grey is the best way I can describe it, no sparkly crystals visible to the naked eye at all.

I don't think I changed anything in my procedure from the O1 knives that I already made that came out fine. I'll go back to Aldo's for 1084 for future projects but can anyone help me save these knives? Let me know what I'm not doing right? Quenching too hot or too cold?

Thanks for the help.
 
Are you 100% sure that its O1?

The supplier you got it from didnt sell you something different?

Just an idea

Matt
 
Non-magnetic is not hot enough for 01, or any other steel if you want a good HT. Non-magnetic is only 1414°, and your target heat should be around 1475°. 01 also requires a lengthy soak at this temp in order to form a good austenite solution with well dispersed carbon. I soak mine for 20 to 30 minutes before quench. There is no need to normalize precision ground 01 if you are doing stock removal. The grain is already as good as it needs to be. It does need a stress reliveing pre-heating soak before raising the the temp to the quench heat though. 01 is a great steel, but is not HT friendly if you lack a temp controled method of heating it. At the proper heat range, you may find canola oil a little too fast in cooling. 01 works best with a medium speed quench. Using canola oil may cause cracking. It may not, but the risk is there.
 
O-1 needs a longer soak than 1-2 minutes, and higher temps than non-magnetic..
Austenitize at 1450-1500F and soak for 10 minutes.

Avoid rapid pre-heat and warpage will be less likely. Best scenario is to use an electric HT oven and pre-heat slowly to 1200F, then ramp to 1455F and hold for 10 minutes, then quench.

If an O-1 blade warps in the quench, just take it directly to a wooden anvil and straighten it. You have about one minute before the Ms makes the blade brittle.


Here is a handy "Wooden Anvil" to make. Oak or maple is great, pine will work:

Cut two 16" long piece of 2X6 or 2X8, and screw/glue them together from one side only...leaving one face just wood ( or use a 4X6). Screw a piece of 4X4 to the bottom. The 4X4 will get clamped in the vise ( which I know you have near the forge).
In one end of the top, saw a 1/4" wide slot in the board , about 6" deep. This slot will be used to take care of any twisting and simple bends.
With this "wooden anvil" and a wooden mallet strategically placed near the quench tank, there isn't much of a warp or twist that can't be dealt with quickly and easily.

This can be made as a dedicated post anvil with the use of a 30" tall piece of oak or maple tree trunk or a section of 12X6 ( or larger) beam. A wooden post anvil is good to hammer the curve out of hot blades when forging, as it won't flatten the edge as badly as steel does. The top will get nice and black and have plenty of "character" marks.
 
Aside from the above, did the blades that failed to harden come from the same bar as the others? Steel is bound to get mixed up now and then, even with good suppliers. The info above is quite correct, but if some hardened and others didn't under the same procedure, it's worth asking why.
 
This is what im thinking.Ive had good sucess with the same procedure you're using although i do go past a bit through non magnetic.Obviously im not doing it 100% correctly,but the half dozen or so knives i made finished out nicely and hard.
mattbrook said:
Are you 100% sure that its O1?

The supplier you got it from didnt sell you something different?

Just an idea

Matt
Click to expand...
 
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Without a reasonably reliable heat control of some kind, one can expect variations from one batch to another. Especially if soaking for any time at all using guesstimation. Stick with the eutectoid, or hypoeutectoid 10XX steels for simple to heat treat steels.
 
mattbrook said:
Are you 100% sure that its O1?

The supplier you got it from didnt sell you something different?

Just an idea

Matt
Click to expand...

Now I'm not so sure. This particular shop only carries O1 and A2. They stock them in cubby hole shelves and unlike other steels I've purchased they don't spraypaing the ends for easy ID. It's very possible that some punk in the stock room put the wrong point of sale stickers on them.
 
LRB said:
Non-magnetic is not hot enough for 01, or any other steel if you want a good HT. Non-magnetic is only 1414°, and your target heat should be around 1475°. 01 also requires a lengthy soak at this temp in order to form a good austenite solution with well dispersed carbon. I soak mine for 20 to 30 minutes before quench. There is no need to normalize precision ground 01 if you are doing stock removal. The grain is already as good as it needs to be. It does need a stress reliveing pre-heating soak before raising the the temp to the quench heat though. 01 is a great steel, but is not HT friendly if you lack a temp controled method of heating it. At the proper heat range, you may find canola oil a little too fast in cooling. 01 works best with a medium speed quench. Using canola oil may cause cracking. It may not, but the risk is there.
Click to expand...

Would I at least get a heat treat that would pass the file test on O1 with my method above? I accomplished it with other pieces using the O1 from the same supplier. Maybe not optimum but they passed the file test and the file still doesn't bite after two temper cycles at 400F for 2 hours.

Were I actually using A2 by mistake would any of my issues fit in to improperly heat treating A2? When I intentionally broke a piece it would not shatter with a hammer right out of the quench, post cooling to ambient temp. I had to put it in a vice and bend it to about 10-12 degrees before it snaped. No noticeable grain inside the fracture, just looks creamy grey and when I run my finger nail along it it feels smooth, not like fine sand paper as I've felt in the past.
 
You very likely got the edge hotter than you think on the previous HTs. Stacy is a little incorrect about the time window to straighten warped 01. It is closer to 5 minutes or even more, so that might explain some of the why the blade didn't break with a hammer blow, but might also be an indication that it didn't deep harden, or harden enough. I have never tried to break one that soon out of quench. One thing for sure, is that you must lose that magnet, or use it just to show you that you need more heat after it stops attracting. I don't think you should continue to worry about the issue. You will never get a good HT on 01 without strict temp control. One thing to understand, is that hardness is'nt everything. At least not when using a file to test by. The file can slide right over soft spots while riding on the hard spots, and never tell you there are soft spots. The file test is all many of us have easy access to, but it is not a conclusive test of the overall blade. The fine grain you saw is expected, especially since you never went much over non-magnetic, but 01 requires more heat to reach a good austentitic solution, and time at that temp. 01 will not grow any significant increase in grain size, until you get a ways over 1500°, so you have about 60° more to go after non-magnetic, and about 25°+ of room for error. Common table salt melts at 1474°, if you can put that fact to use, but it would need to melt as a result of conduction though the steel, rather than from a direct heat source. When I remove an 01 blade from my oven, set at 1475°, it is bright orange-red in my lighted shop. To my eyes, but color intensity varies among different people.
 
Thanks for the input, LRB. I think I'll try to make something useful out of these if I can. Maybe if I can straighten the warps and do a little regrind I'll send them off for pro heat treat. I'll stick with Aldo's 1084 for now.
 
spareparts said:
Were I actually using A2 by mistake would any of my issues fit in to improperly heat treating A2?
Click to expand...

A2 requires a still longer soak (20-40 minutes) at around 1750F. If you did get A2 by mistake you would have
been far short of minimum HT requirements so *maybe* what you experienced would fit. Also note that A2 is
an air hardening steel so it will get hard without any quench if you get it hot enough for long enough.
 
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