Heat treating High speed steels

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Storm W

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Im doing a large batch at least for me of M4 and M2 knives. Since my dewer lost vacuum im going to use high temper. Since I am going to heat treat a couple of other knives while the oven is hot i will at least have dry ice at the same time and was planning on adding in a cold treatment as well. When looking at the directions on AKS it talks about using cryo after the first temper and says it should be tempered after. Would i stay with a high temper. I assume that I would but thought I would ask.

These are by far my favorite types of steel and Im finally getting around to using them myself. I have a number of blades that @willie71did fir me at 66Rc with a low temper and am looking forward to comparing the difference. I was just starting to work with them a few years ago and a move interrupted me. I remember mt test chef knife blade out of M2 to resist rust very well but these high temper blades seem to pick up a fair bit of rust. Does anyone have advice to offer about using these steels especially in the kitchen? Larrin Larrin are you interested in doing more testing of these steels? I can provide samples of what @willie71heat treated with a low temper as well as mine if there is anything that might be gained by a cold treatment combined with a high temper. I can't offer more than the coupons though. Sorry I don't have a surface grinder.
 
The low temperature DI treatment is sufficient.
After hardening and cooling to ambient, place in the DI bath to cool to the DI temp (a 10-minute hold is plenty) and remove. Allow to warm to ambient and immediately temper at 1000°F. Cool to ambient and temper again. 2-hour tempers are recommended.
 
If you going to the high tempering route I don't think any freeze treatment is necessary. High tempering will get you noticable lower corrosion resistance in any steel tho.
 
Larrin said:
We tested some M2 toughness specimens with both a low and high temper that Warren heat treated. Here were the results:
1975-cryo-400 = 62.8 Rc, 6.6 ft-lbs
1975-no cryo-1000 = 61.8 Rc, 6.6 ft-lbs
2050-cryo-400 = 64.0 Rc, 6.4 ft-lbs
2050-no cryo-1000 = 63.6 Rc, 5.9 ft-lbs
Click to expand...
I was planning on going for around 66Rc the same as the cold treatment. I wasn't sure if you interested in more data points for high speed steels. Assuming its thick enough stock I don't mind donating some of what he did for me. I thought it might be interesting to see if cold treatment after high temper does anything. I suppose i could see if i could get a small quantity of LN if that was important. Im interested in seeing how low and high compare in the kitchen and holding a fine edge. My early testing with Warren's low temper had it hold a super thin fine edge. I'm interested in this range of steels since they still take fine edges and have the hardness to hold onto a lower edge bevel. I'm really interested in your MagnaCut because i have noticed that M4 looses that ultra fine edge when cutting acidic foods like citrus. Im hoping to try to find the end of where steels top out for that fine edge holding with general use in the kitchen. Does that end with M4 or could something like T15 hold up. I know both my knifes and Warren's are holding up at 66Rc I'm interested in seeing where that hardness component breaks down. My knives are in the 0.001"-0.003 at the edge and from what I understand hardness is important for holding up to that lower bevel angle. Lol my personal grial project. Once I get a new dewer I am eager to try both of your steels. That new one sounds near perfect for the type of edge i like although it won't have the retention.
 
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