Cpm-m4

[knarfeng]

I sincerely doubt that Latrobe would do that and that Bohler would supply them with the steel if they knew it was used for that purpose. In any case, I cannot for the life of me figure out how Latrobe would remove 0.4% of the silicon content from the steel after it's already been melted.

Still, I feel the would be fairly different in terms of performance, again because IIRC only Bohler uses third generation powder metallurgy process as of yet.

21st century corporations sometimes do odd things because they are run by accountants, not engineers.

However, like I said earlier,
- I have heard it said that the alloys are the same. I do not know it to be true. Certainly the compositions are extremely close.
- I consider PM steel performance to be much harder to predict than that of melt alloys. More variables to control.

You asked, and I gave you the information I had.

 

[hkpokes_you]

ZDP-189 is in league with 440C for chippyness if both of them are run at typical hrc; 57-59 for 440c, 64-67 for ZDP189. Hitachi's ZDP-189 datasheet isn't hard to find if you google for it. CPM M4 is roughly five times tougher at 64-65 than either of them.

I have never had rust problems with my CPM M4 blades, and I'm not anal about maintaining them really. Just use some common sense.

In my opinion -- unless you're around salt water, or you're looking to make a sword, CPM M4 is one of the best steels to make blades out of.

It's a pain in the ass to grind and finish -- but that's my problem, not the customer's.

 

[Big Mike]

In any case, I cannot for the life of me figure out how Latrobe would remove 0.4% of the silicon content from the steel after it's already been melted.

:thumbup: :foot: :thumbup:



Yeah, ...what he said,


...getting that pesky silicon out might be a bit tricky.





Big Mike

 

[hkpokes_you]

Nobody is adding or removing silicon from someone else's steel. They're very similar steels -- but they are are not the same steel. And, to my knowledge, Bohler uses a superior PM process. I don't have any experience with the steels firsthand, and I don't know the details of the PM processes, save for the fact that Bohler says they're a generation ahead of the other companies. Maybe the silicon is in the Latrobe stuff to kill the alloy (remove oxygen from it), maybe Bohler kills it with trace amounts of Aluminum, Titanium, or Boron rather than easily detectable amounts of Silicon. All these elements, and a few others, are about a hundred times 'more potent' than Silicon, Chrome, or Carbon, as alloying elements; and typically you don't get good figures on them from mills. I suspect that the explanation for how or why Bohler didn't put in the silicon makes sense as part of a bigger, more complex, technical story.

Interesting side-note -- PM versions of M4 at 63HRC are 20% tougher than 420 steel is at 50 HRC. That's why people spend afternoons chopping up golfballs, soda cans, and 2X4's with CPM M4 blades.