440c vs. ATS34

Milt

Milt

Joined
Nov 16, 2008
Messages
260
I posted a pix of a fillet knife I made from 1/16" 440C on Knife Dogs. A fellow suggested I try ATS34, so I did that. Both steels came from Admiral Steel, and I was quite satisfied with the products. The 440C was thicker than 1/16" as Admiral said could happen. The ATS34 was true to size and was very black and was heavily coated with a thick cosmoline type oil. The ATS 34 was annealed and seemed to grind easier than the 440C. I have not heat treated the ATS34 blade yet as I am relining my forge, so I cannot com pare the final product with the 440C blade.

Question 1- Why is ATS34 black?

Question 2- Why the heavy coating of oil? (rust?)

Question 3- Your opinion of the 2 steels.



Thanks,



Milt
 
Black is oxide from HT, oil for rust.
ATS-34 is an improvement over 440c due to the Mo addition.
Remember that ATS-34 = 154CM .The two powder steels are even better , CPM154 = RWL-34
 
ATS34 should outperform 440C by a wide margin. It has better wear resistance - better corrosion resistance and better through hardening than 440C. Having said that, ATS34 (the Japanese version of 154CM) sometimes (maybe 1 - 2%) has inclusions that have a habit of showing up on an almost finished blade. This is rare, but noteworthy.

It also bears mentioning that these steels require a long soak at specific temperature. I'm not a smith, but I understand this can be challenging with a forge. Colors and Curie point are not useful. To get the most out of them, it may be best to use a temperature controlled oven.

Rob!
 
If both steels are properly heat treated, they aren't that different. From personal experience with both, it takes a lot of continuous use to notice any difference in wear resistance, hough I've seen it written that ATS-34 will outperform 440C in that area by 5-10%. ATS-34 is not as stain resistent as 440C by a noticable margin, and 440C takes a better finish. I've used a good bit of Admiral ATS-34 lately on a set of kitchen knives, heat treated by Bos, and it has a very noticable "orange peel" look to the finish after hand rubbing to 800 grit. Never seen 440C do that.

Rob is correct that both need to be heat treated with really tight temperature controls at high temperatures. Sending it out is the way to go if you don't have access to a heat treat oven and cryo equipment.
 
Both are good steels, if properly heat treated, but 440C will be the one with better corrosion resistance.
 
As Mete pointed out ATS34 = 154CM. The following from Crucible's data sheet on 154CM

----------------------------------------
Crucible 154 CM is a modification of 440C
martensitic stainless steel to which molybdenum
has been added. 154 CM has better corrosion
resistance, better wear resistance and better
hot-hardness than 440C. For knifemakers, it
offers better edge retention than 440C. It also
has higher attainable hardness and better​
through hardening characteristics than 440C.
_______________________________________

I'm still a little uncomfortable defending ATS34 though. The alloy is a great blade steel!

Rob!
 
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