Heat treating 01 tool steel

[Deni822]

Hi team,

Just wondering if anyone has a high temp oven or know someone who does, to harden 01 tool steel? It needs to get to critical temp of 1350-1400F for 15-20mins. I would greatly appreciate any leads. Its a one-of project for me, so don't really feel like building a forge or a home made oven.

Thanks.
Mark

 

[HuronMachinist]

I use torches. Quench it afterwards.

 

[PeterT]

I don't have a ton of experience but same here, use a torch on O1. These are relatively small pieces like maybe 2 cubic inches. The special heat insulation bricks from ceramic places bricks make a huge difference getting to temp quicker & using less gas to maintain. And generally safer. I just stack them to suit like a semi open pizza oven. Now the 15-20 minutes is a pretty long heat soak time to hold for this mode, at least I think I'd have trouble dancing the flame & maintain that shade of red for a long time. Is it a bigger piece? Ovens are luxury items but I sure would like one.

 

[Deni822]

Thanks guys. Yeah, the torches are always the way but I was hoping to finding someone with an oven for maximum control and hardness and maybe minimize warpage that can result from uneven heating. I'll probably make myself a tiny forge with the light white bricks and give it a go.

Cheers.

 

[Bofobo]

The small oven of bricks is a great way. That lazy machinist on youtube has great videos about heat treating

Its two part but here is the first

 

[HuronMachinist]

If you are really concerned about warpage I would make a treating fixture. But to be honest if you take your time with a rose bud torch and heat everything slowly you can get as good of results as an oven. Drawing it back after quenching is actually more important than the heat treating process. Wrapping the part in wire and boric acid also helps. Also doesn't hurt to leave it in a toaster oven at max temp for an hour before you start.

 

[Chris Cramer]

Depending on how you worked it, 01 steel I've read is usually normalized before hardening if hot worked to avoid warpage. What is the soaking temperature and the cooling rate to normalize 01 steel? 01 will air harden, so I've decided to try letting it cool with my forge after soaking it for 45 min at 700 - 800 degrees c; but would cooling the blade that slowly cause it to aneal rather than just normalize?

 

[PeterT]

Chris, to my understanding, I don't think O1 can be hardened by letting it cool in still air. The oil quench medium is to reduce the temperature at an accelerated rate. Water is faster yet. If that rate isn't met, then I believe what you have accomplished is annealing. For example taking a hardened file up to temperature & gradual cooling will bring it to a state you can once again machine like ordinary steel. This chart kind of illustrates whats going on with the slope curves & temperature rate on X-axis. If I'm missing something, let me know.

 

[Janger]

Download the phone app "Heat Treater's Guide Companion" which is published by the ASM Heat Treating Society. It details how to heat treat by alloy type. Temperature, soak time, annealing, etc. The instructions are brief but detailed. It's free too. O1 is in there.

 

[Janger]

I think I'm allowed to quote briefly "Hardening: heat slowly. Preheat at 1200F. Austenitize 1455 to 1500F to 10 to 30 minutes, then quench in oil. Quenched hardness 63 to 65 HRC." Prior to that it talks about how to normalize, how stress relieve, how to pre heat, harden, temper...

 

[Chris Cramer]

Thanks for that app. I usually use canola oil to quench my blades. For 1084 it was recommended to preheat the oil to 400 feg f. What temperature does the oil need to be preheated to when quenching 01 tool steel?

 

[Janger]

When we did this at sait we quenched in oil at room temperature. It was a petroleum oil. @kevin.decelles do you remember what the steel was? O1?

 

[PeterT]

This site has some HT details on tool steels.
http://www.astmsteel.com/product/aisi-o2-steel-tool/
Some of the blade forums I lurked on have all kinds of resources & Q&A forums. But some of the specs are pretty tight, meaning heat control ovens, salt baths, inert gas foils etc. You kindof have to work with the equipment you have, or at least appreciate he limitations,

 

[kevin.decelles]

When we did this at sait we quenched in oil at room temperature. It was a petroleum oil. @kevin.decelles do you remember what the steel was? O1?

I believe it was 01


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