PSF27, what do we know about it?

[Doc Dan]

Hi folks

What do we know about PSF27 steel in reality? Is it like CTS XHP or anything? What characteristics does it have?

The new Junction looks like a knife I have been waiting on from Spyderco and I want to understand a bit about the steel.

Thanks

Doc

[Ankerson]

More like CPM D2 actually.

Very nice steel, takes a good edge and holds it for a good time.

[bearfacedkiller]

I would agree. I passed on the mule in psf27 but I do have the Bradley Bowie. It is like CPMD2. For a woods knife it is a good steel. Not too hard to sharpen and holds a great edge. I will definitely be picking up the Junction. It is pretty light weight for having a 4+ inch blade. It should be a good hiking companion.

[Cujobob]

Quite a few respectable makers are using this in customs now. I've heard good things but yeah it's most similar to D2 as was mentioned.

[PayneTrain]

I know I like it! Even though it is very similar to D2, I'm finding I can treat my mule like it's fully stainless, unlike D2. Isn't there a drop of nitrogen in there? Could that be it? Or am I just getting lucky?

[bearfacedkiller]

I broke down half a pig with mine when I first got it and had some light but instant staining. I only use mineral oil as a protectant. It hasn't stained any since then though and it has seen some use in the woods as a camp/survival knife but it never really got wet during any of that. I live in a very arid climate though.

[Skywalker]

I know I like it! Even though it is very similar to D2, I'm finding I can treat my mule like it's fully stainless, unlike D2. Isn't there a drop of nitrogen in there? Could that be it? Or am I just getting lucky?

According to zknives, PSF27 and D2 are pretty much identical, though CPM D2 had very slightly tweaked molybdenum, vanadium, and manganese levels. Doesn't appear to be any nitrogen.

http://zknives.com/knives/steels/steelg ... d2%2CPSF27

[PayneTrain]

Ah but according to Spyderco, it does! .30%!
http://www.spyderco.com/edge-u-cation/index.php?item=3
I knew I saw it somewhere. I wonder what the truth is...

Edit: Alpha Knife Supply reports some too, though much less.
https://www.alphaknifesupply.com/zdata- ... elC-D2.htm
I'll keep googling for more answers.

[Doc Dan]

Thanks guys! I am really stoked about this knife. It meets my basic requirements for a general hiking and outdoor knife of 4x4 (4 inch blade at 4 oz) with a good steel. I am ready Spyderco, where's my knife!?

[bdblue]

The CHEMISTRY is similar to D2 but the production is different. Some custom makers have felt like the properties are enhanced due to the method of production so it may be unfair to compare it directly with D2.

[Doc Dan]

It is tougher than D2? More wear resistant? Or is it about the same?

[Ankerson]

I would say similar to CPM D2.

[bchan]

Is PSF27 stainless or not? Does anybody know?

[hoimin]

Is PSF27 stainless or not? Does anybody know?

It does not fully qualify as stainless; it also hasn't been very difficult to take care of for me.

[akaAK]

In limited kitchen use so far it has performed well, good edge retention (haven't needed anything more than the factory edge for now). Haven't seen any issues with staining or patina but that may be more a function of what I have cut.

I think the comparison to CPM D2 is a good one.

[bearfacedkiller]

I have found it to be more stainless than M4 but a little less stainless than Cruwear. I haven't got any staining with Cruwear after a lot of use. PSF27 seems to resist staining pretty well. It should be easy to care for with just a little effort.

[Skywalker]

Ah but according to Spyderco, it does! .30%!
http://www.spyderco.com/edge-u-cation/index.php?item=3
I knew I saw it somewhere. I wonder what the truth is...

Edit: Alpha Knife Supply reports some too, though much less.
https://www.alphaknifesupply.com/zdata- ... elC-D2.htm
I'll keep googling for more answers.

Huh. Well, that's interesting... Almost makes me want to set up a profile on Carpenter's site to see what they say, but they want an awful lot of info to do that.

[Doc Dan]

"PSF27 is made by a process called spray forming. Spray forming is different than particle metallurgy. To spray form steel is melted and sprayed to form a billet. The result is D2 with better edge holding and toughness than cast D2." (Alpha Knife Supply)

Better edge holding and toughness are good things.

[Zenith]

From what I could gather it appears to be. From Steel Heat Treatment Metallurgy and Technologies, George E. Totten the following table is published on page 678.


Comparison of Properties (Relative Values) of High-Speed Tool Steel Made
by Various Processes





He accredited: Source: From G. Roberts, G. Krauss, and R. Kennedy, Tool Steels, 5th ed., ASM International,
Materials Park, OH, 1998, p. 41.

One would have increased toughness, grindability, and bend strength over Ingot D2, but falls short on other categories vs PM process.

[PayneTrain]

Ah very nice, Zenith! Those figures make sense in my mind. Spray forming seems similar to powder metallurgy, if not identical, except that it results in slightly larger grains, and therefore carbides.

This reminds me of something I recall reading about M390, 204P, and 20CV. As I recall, they are made with 3rd, 2nd, and 1st generation powder processes, respectively. Knifeworks describes 20CV in the context of the Benchmade 551-1 as having more wear resistance, but less toughness than M390. I wonder if it's a similar comparison, 20CV being made with larger carbides due to a different (earlier?) powder process.