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How important is the heat treat?

Jul 22, 2000
This is a question best answered by our resident steel experts. How important is the heat treat OVER the steel type. Is there a balancing act required? Do we consumer level knife knuts ignore this factor too often by going strictly with steel type?

There there seems to be a generalization that AUS-8 is better than 440A, and ATS-34 is better than AUS-8,...

I would think that how the steel is heat treated would be a critical factor. That a properly heat-treated AUS-8 would be preferable to a brittle, poorly heat treated ATS-34.

Are the steel suppliers, and heat treat methods of most commercially made knives pretty similar? I.E. is Benchmade's 154CM, similar to Microtech's 154CM?

There just seems to be a generalization that a knife is good because it's blade is made of ATS-34, CPM 440V, D2, or whatever. Many manufacturers use this as a selling point. Obviously there are other factors.

[This message has been edited by Full Tang Clan (edited 02-03-2001).]
Without proper heat treating the best steel can be junk. Most high allow steels are not well heat treated in large batches so you can probably answer your own question about whose 154CM is best.

IMHO if Paul Bos heat treats it, it's as good as a steel can get. He has heat treated CPM-3V for me that has performed magnificently, while the same steel heat treated by others has not measured up.

Good question, and your perception of the fact that this is not black and white is right on.

Jerry Hossom
The New Tom & Jerry Show
Yes, you could say that the heat-treatment is more important than the alloy. That is because the heat-treatment controls the physical properties of the steel over a very large range. Obviously some steels have superior properties compared to others for use as a knife blade. But a good heat-treatment in a blade made from relatively poor steel may well outperform a badly heat-treated blade of 'superior' steel. Heat treatment is the most important part of blade making for optimizing edge-holding and toughness in any steel.

I'm lazy so I will refer you to This thread for more info on this topic.


[This message has been edited by Paracelsus (edited 02-03-2001).]
Uh, I suspect you know the answer to this already.

Heat treat is, say, 60% of any knife's performance.

20% is the actual steel selection.

20% is the blade shape/grind, depending on what purpose the knife was designed for.

They all synergize into a performance blade.

And yes, and mediocre steel with an optimized heat treat can outperform a great steel with a cruddy heat treat.

With Talonite/Stellite the only real exceptions, ultimate working hardness of a blade is proportional to edge holding. Then the balancing act of hardness vs. toughness (resistance to chipping). I.e., you can get great slicing ability out of O1 at Rc64, but it will be brittle. CPM440V is somewhat of an exception (it performs well at Rc56-58), but is overshadowed by CPM420V in every category anyway.

All else equal, the harder steel holds a better edge. Anything below Rc56 is generally either not going to hold an edge for long (slicing, push cutting) or is designed for chopping (toughness is byword).

And given equally optimized heat treats, ATS-34 will always outperform AUS-8 when slicing and push cutting are the issue. It's the molybdenum carbides in ATS-34 that give the edge, no pun intended.

ATS-34 has 0.35% more carbon (providing carbon for both carbides and hardness of iron matrix) and also has 4.0% moly vs. 0.35% moly, and moly makes molybdenum carbides that are 72-77 Rc.

[This message has been edited by rdangerer (edited 02-03-2001).]
Is heat-treating the only thing done to a steel after it's smelted? Maybe there's more to it besides alloy and heat treat. How is steel actually made?
I don't think heat treatment is either good or bad, like a light switch is either on or off. There is a continuous scale from completely useless to best possible, that covers every point in between.

Hey Mike, far out. I am not sure I understand what the heck you are trying to say. Sorry if I sound confused. Maybe you could enlighted me and explain your post a wee bit more laddie.
IMO heat treatment is by far the most important part of making a great blade.


Sorry about that. . . I agree that a good steel that is poorly treated will be worse than a lesser steel that is well treated, however, the heat treatment on the same steel can range from poor to excellent to anywhere in between.

I believe the heat treat is the singlr most important element in the performance of the blade. As stated by others in previous posts an otherwise excellent steel with a poor heat treat will not perform as well as a mediocre steel with an excellent heat treat. Because of this steel performance will vary from maker to maker and manufacturer to manufacturer.

Dennis Bible

I never liked ATS-34

Then I tried a Benchmade 855 in it.

It holds an edge better than my Gerber ATS-34 blades, by about 30% On a smaller knife!

I think it has a higher Rc
Gerber is 59-61 I bet mine were in the high 50's, while the Benchmade was in the low60's.

I was often puzzled how most claimed that M2 only gave similar performance to ATS-34, but was tougher. I found it 200% better than ATS-34. Now I know why! The heat treat was not as good I bet!


"To strive to seek to find and not to yield"
Ranger motto

A few useful details on UK laws and some nice reviews!
Certified steel snob!
As a kid I was a pyromaniac (ok--so I'm still a pyromaniac). Anyway, I liked to heat things up on our gas range till they would glow and get soft. Commonly I was playing with coat hanger wire, but anything I could get my hands on was fair game. This included some of mom's kitchen knives.

The knives would glow in a satisfying way and when they cooled they'd have bluish rainbow tints. (Uh-oh, mom's going to notice that.) I also noticed that the steel became soft as copper--totally useless as a knife. Hmmmm? I learned about annealing.

To cover my tracks I asked my dad about how these things worked. He said you could heat steel up and quench it in water to make it hard. I'll be darned if it didn't work! The trouble was now the tip broke off the blade when I tried to sharpen it. My uncle suggested oil quenching which worked a bit better. Then I read about tempering in a book. I couldn't get it right and kept getting blades that were too hard or too soft.

The bottom line was that without skillfull heat treatment I couldn't get those knives back to decent performance. They had started out ok before I ruined the heat treatment. They were still made from a nice cutlery alloy and even had some vanadium in the mix, but proper heat treatment was everything.

Thanks to all the replies for the little lesson on the importance of heat treat, and that not all ATS-34 (or other steel) is created equal. I'm the first to admit that I've really overlooked this.


If heat treating is arguably as important as the steel (within reason of course), how do we -- at the consumer level -- know which manufacturers have good heat-treats?

I mean, I rather have a good AUS-8 knife from manufacturer A, than a crappy 154 CM knife from manufacturer B.

The only information (or misinformation) we are given are often the steel type and a standard Rockwell hardness straight off a chart. It really doesn't say how rigid the blade from that particular manufacturer is and how well it is heat treated.

Okay, let's me be blunt: Which manufacturers have excellent heat treats, and which are bad?

[This message has been edited by Full Tang Clan (edited 02-05-2001).]
Congratulations! Wonderful discussion.
You are on the verge of finding the difference between performance and marketing.
Use your knives and you'll know.
Happy sharpening