Thread: Looking for the best heat treatment for O1

Since the temperature already correlates directly to the temperature of the steel, isn't thermal paint a bit redundant?
It's O1 we're talking about here, which is very easy and forgiving in heat treatment.

I am just learning all this myself but this part of your post left me wondering exactly what is going on at this moment.

"" I use 1 l canola oil for quenching. I'm not sure that an appropriate period of time inside the steel. I tried 5-10s and 30s periods. I tried to reach 400F before the air cool to room temperature. How can I monitor this process? ""

Everything else sounds perfect. I did have a thought about how long you leave your blade at 1500 degrees. It was the only other piece of the puzzle you left out. In other words are you sure your blade is reaching that temp ?


""" When I use HT-foil should I deep into the oil with foil or not? Because of the short time. And during the tempering process? """
I would forget using the foil until you are successful with everything else. You have to grind more anyway and you can protect the tang with other methods later.

Originally Posted by 10Pups

Everything else sounds perfect. I did have a thought about how long you leave your blade at 1500 degrees. It was the only other piece of the puzzle you left out. In other words are you sure your blade is reaching that temp ?

Around 15 minutes. Yes I am sure.

Originally Posted by 10Pups

""" When I use HT-foil should I deep into the oil with foil or not? Because of the short time. And during the tempering process? """
I would forget using the foil until you are successful with everything else. You have to grind more anyway and you can protect the tang with other methods later.

OK, thanks!

Just another thought.... Maybe try a different steel supplier ? Other than that I am out of suggestions. Like Bruno says, O1 is very forgiving and many treat with less control than you have over the process.

Unfortunately, I can not really sorted out between the steel supplier in Hungary. Your comments on the basis of more and more I think the problem may still sharpening technique. But any other razor I honed has never been problem like this.

I would send&show my blade to one of more experienced custom razor maker or honing expert, quite a few exist in our very forum. I would also check the hardness of the blade with a file.

Good idea, thanks! The hardness is enough(sometimes to hard ), the sensitivity is my problem.

On the honing side you may be making deep scratches when starting the bevel that remain to the end of your progression. In other words if your using something like a DMT 325 to shape your bevel and then don't spend enough time at the 1k level the first stria may be causing problems later. The best way to eliminate that is changing the direction between stones and make sure you get all the previous marks out. A loupe is necessary of course.

Too hard will not hold an edge very well either.

Thank you for your help with my question. I understand what you are doing now...

First, the bars of O-1 are likely just fine from the steel mill, but that you have added the insurance of the normalizing routine will take care of any unusual heat history that might have happened to the bar when you did not have it under your control. Steel mills should not do much out of the ordinary but I have had "factory" bars that did not behave as they should. It helps to always be observant about such things.

Second, that you are grinding and not forging means you have probably avoided any large grain/particle problems already. Grain growth in O-1 requires temperatures that exceed 815C/1500F far longer than 15 minutes. I think your process is a good one. Very likely you could save yourself shop time by not having to normalize your blades (it's more for people who forge their own blades at uncontrolled temperatures). If you noticed any warping during the normalizing process, that is the place to correct it. And remember it (journal - notebook) about that batch of steel from that supplier for the next time.

Third, I don't think your oil temperature is too hot. I hardly ever heat my quench oil for O-1 (shop room temperature maybe 50F) and it will produce good hardness. I am not getting any feedback that the edges are crumbly. You can experiment by doing quenches at lower temperatures. But I am spoiled by better equipment and with good thermal controls I can predict hardness to a very fine degree just with time and temperature.

As has been said, O-1 is almost the perfect beginner's steel, very forgiving, and a highly under rated good performing blade steel for razors and knives.

Lastly, we're back to either edge geometry (spine width to blade width) or bevel setting/honing techniques and there are good comments here already about that.

Greg, you have some top notch guys here answering your questions & Mike has forgotten more than I will most likely know.

Do you have one of the razors in hand that does not meet your expectations? If so, would you consider breaking it and taking some good pictures of the particle grain? Even if you can't get pictures, it will show more than your guessing...besides, it's not performing to what you expect.

Only other thing I can think of is your quenchant temperature. I have found that cold oils don't quench seem (to me) as well as warmer oil.