Heat Treating My First Blade. Questions.

[Tbonz]

Heat Treating my first Blade, 01 Tool Steel. 1. According to the info from Starrett,
Hardening 1450 - 1500 degrees.
To achieve an RC of 58/60 temper at 400 - 450 degrees, One hour.

1. How long should the knife soak at 1450 - 1500 degrees?

2. When I Quench the knife in 125 - 150 degrees oil, can I just submerge the blade and part of the tang? Or does the entire knife need to be submerged in the oil? How long should the blade be submerged in the oil?

3. After the quenching and the blade has cooled . I plan on putting it in a preheated Oven at 450 degrees for an hour. How should the blade be cooled after the first tempering, Let it sit till it reaches room tempature or does it get put in the oil again?

4. After the final tempering how could I test the hardness without an RC tester?

Thanks for any info on Heat Treating 01 Tool steel.

Tim

[mete]

You can't test hardnes [numbers] without a hardness tester but you can do a file test to make sure ,it shouldn't bite in. When you quench put the blade in but not the tang, when it has reached the temperature of the oil immediately temper. If you want temper a second time [recommended for O-1] just let it cool in air to room temperature then temper again. Soak for 10-15 minutes.

[Tbonz]

Thanks for the reply mete.

I Heat Treated my first knives yesterday.


My first attempt at heat treating a knife made of 01 Tool Steel did not come out. Can I Heat Treat it again?
My 2nd attempt was with a knife made of 154 CM and this time it worked. I
credit this to the information provided on another thread. I tempered it twice at 450 degrees for an hour each time. I'm hoping I ended up with a blade with an hardness of about 58 - 59 RC. I did the file test and it slid along the surface.

[JeridJohnson]

I believe you should be able to heat treat the O1 again with acceptable results.

[Rocket_Jason]

Tbonz-

Read this.

http://www.knifenetwork.com/forum/sh...9&postcount=11

[rlinger]

I am experiencing my best soak time for O1 at about 9 minutes. That is about 9 minutes after the blade has equalized - became the same temperature throughout its thickness. If your equipment permits bring your blade up moderately to 1200 F and hold there for about 7 minutes, then ramp as quickly as your equipment provides to about 1475 F and soak there for about 9 minutes. Quench IMMEDIATELY and for long enough that it barely smokes when pulled from quench oil. If still too warm return to quench for a few more seconds. Allow to still air cool to NO LESS than hand warm (125 to no greater than 150 F). Place IMMEDIATELY into PREHEATED tempering oven. Temper a minimum of 1 hour at 400 F. Allow to still air cool to room temperature. Repeat temper at 375 F / 1 hour. Edge the blade and test for chipping by chopping hardwood and twisting edge while in the hardwood. If a running of the finger nail detects chips temper again a few degrees higher and repeat testing. A maximum of about 425 - 440 F temper should be all that is required but be sure your tempers are a minimum of one hour per. If you find you can not get good edge retension without tempering at least as high as 400 F (the absolute minimum you should want for your primary temper) you have misperformed an earlier part of the heat treat. Upon raising temper as high as about 440 F and you continue to get edge chipping you may have either over soaked (that is the time at austenitizing temperature - the 1475 F mentioned above) or the soak temperature was too high. If no or little edge chipping but edge retension (sharpness) is poor you may have soaked at too low a temperature or for not long enough.

RL

[Messinger]

Tim,
I'm a newbie also, but I'll quote two of the fine members here who've been great help to me (whether they knew it or not!)

knifemaking - tempering O-1 pt2
(Frank Warner)

I'm sure Jason will reply soon but thought I'd give my take on tempering 01.

I've worked a lot of 01 and, for me, the best temper is a triple temper.

I put my blades in the wife's oven at 325? as soon as they're cool enough to handle from the oil quench. Don't worry about the scale at this point. Out of the oil and into the oven quickly. Leave them for an hour or so, although longer wouldn't hurt.

Remove from oven and let cool to room temp. Then you can remove the scale and re-polish to near-final finish. At the very least you want some bright steel before the next temper.

Temper a second time at 375?. Watch this one. Keep your eye on the steel and when you start to see a light straw color develop (might take 15-20 minutes for small blades, 30-45 mins for larger ones), pull it out and let it cool again.

Polish the straw color off before the third and final temper. More shiny steel.

The final temper is at 400?. You don't want to go any higher than that, and you want to watch this one, too. Let the straw color go a little darker than the second temper. When it starts to look brown instead of straw, you've gone a little too far. Purple or blue (not likely at 400?) means normalizing and starting over. You want a pronounced, noticeable brownish yellow straw color.

All the tempers should be done as close to each other as possible. The first one is rather important and should be done as soon as possible after the quench. Have the kitchen oven preheated when you quench and ignore any scale until later.

This will give you carbon steel that's real close to the 58-60 Rc ideal for most blades.

-Frank J Warner

Jeff, the way I am HT-ing my O-1 is :-

(usually) edge hardened, even on small knives (for the heck of it), go immediately to an oven temper at 375F for 1.5hours. Allow to cool to room temp (about 1hour) Into my deep freezer (about 14F) for up to 72hours. Then allow to warm to room temp and into the oven again for 1.5hours at 375F, cool to room temp over 1hour, temper again for 1.5hours at 375F.

The so-called "cryo" stage is less effective at that sort of temperature, but I reckon it still makes a difference. The more important stages are the multi-tempering cycles. Its important not to short cut the timing because the benefits of the thermal cycles require passage of time.

My technique seems to consistently produce 60, maybe up to 60.5 Rockwell at the edge, as tested by the guys who do my high-alloy blades.

I'm not sure why the spine on your blade has gone a purple. Generally, the longer the tempering time, the more oxidation occurs on the blade. This way the "tempering colours" could actually change. But it should be uniform across the steel. I suspect you may have some oil on the blade preventing the colour change on the rest of the blade. Please note - from what I know, this sort of "extra oxidation" because of a longer time in the oven DOES NOT MEAN that the hardness is lower.

I am definitely no metallurgy expert but so far so good, these methods seem to work. Jason Cutter.

Of late I've been using Jason's method with wonderful results. On the last few I have deviated by lengthening the temper cycles to from 2-4 hours. No chipping, but a couple have felt too hard so I did another temper at 385F and got what I was after. At 400+ they start to feel too soft for me - but like I said - I'm a newbie so take my words with a grain of salt.

-Ben

[rlinger]

As an example, here is one I most recently did. It is O1, 1/4 inch maximum spine thickness. Heat treated as I described above in my first posting except that it was given a cryogenic treatment after a snap temper of 320 F / 45 minutes and the tempering was twice with the first temper being at 410 F / 1 hour. The second or last temper was at 430 F / 1 hour. The resulting tested Rockwell hardness is 59.5 - 60 HRc.

Here is another, but with no cryogenic treatment: Same as described in my above posting except that it was triple tempered. First temper: 400 F / 1hour. Second temper: 420 F / 1 hour. - 60 HRc after second temper. Third temper: 400 F / 1 hour. Resulting tested Rockwell of 59 HRc. That blade was 6 1/4 inch long, 1/4 inch thick O1 with no distal taper.

Concentrate on proper soak temperature and proper time at your particular soak temperature and on quickness into quench, how long in quench, getting into preheated temper immediately upon acheiving hand warm, and at least one of your two or three tempers being at a minimum 400 F.

Colors are nice and I do like seeing that straw gold. Blues and purples out of tempering are nasty to us when tempering simple carbon steels. Rather than depending on color, depend on good oven thermometers and time in temper. Going by color alone can be misleading. If you see blues and/or purples though caused by tempering your thermometer is broke.

RL