Hi guys, a knife enthusiast here! I find the present pocket knife market exciting and stupid in that so-called “sprint runs” for existing models abound, featuring blades made from a new-fangled steel that promises greater rc hardness, wear resistance, edge retention, the usual pitch. People ruin themselves to get in the pre-ordering bandwagon, only to keep the knives in their safes for later re-sale on the bay. I’m looking for dope on the following:
Why is powder steel so expensive?
What aspect of it gives greater hardness, wear resistance, retention compared with the usual “ingot” tool steel?
Is there no end to the features this technology promises? Will knives with edge hardness of rockwell 70 be common place in the future?
The powder steels - eg VG10, S30V, S90V are sintered powders. They are vastly more expensive to make as they start with very fine powders of the constituent metal components, mix them together and then sinter them in a mould. This process allows alloys to be made with metals that cannot be mixed in a simple melt. The metals are never actually fully molten during the sintering process, but rather they diffuse. The process takes a long time. For instance you can alloy two metals one of which has a vaporisation point lower then the melting point of the other. Thus you can make alloys that are simply not possible otherwise, greatly increasing the possibilities in better metals. Control of the powder size and crystallisation progress is also possible, leading to control of structure not possible with molten metals. Compared to pouring a billet of high carbon steel this is orders of magnitude more expensive.
I believe sintering (at least for objects like this that require structural strength) usually involves compressing the powder mix in a die, inside a big-ass press - resulting in a crumbly, yet somewhat solid blank that can then be heated to fuse the particles.
Non-compressed items can be sintered (for example, 3D-printed metal objects), but usually only for decorative or non-functional prototype purposes.
Thanks FV! I hope you don’t mind a second brace of questions. I’m strictly at the user level:
What component/feature of PS gives greater wear resistance? Knife forumers say it’s the vanadium carbide content.
What role does chromium carbide play?
Last, I’m wondering if you’re familiar with the monster PS in the horizon: CPM rex 121. Whereas the hardest PS available have edge hardnesses from 63 to 65, rex boasts rc 70 at the edge. It’s main component after steel is tungsten (10%) and cobalt (5%.) That’s mind-boggling. My zdp 189 spyderco at rc 64 is already harder than a file. Sharpening it is like sharpening a diamond. Now how would one sharpen the rex? Estimated price for a top folding knife in cpm rex is $500, compared with the already eye-popping price range of $300 to $375 for those in s90v or m-4. Thanks again.
Does one really notice a boost of 3 Rockwell hardness points? I have one of the original Böker Leopard III Damascus knives with an HRC of 65-67 and that just uses ordinary steel (from WW II Panzer tank barrels IIRC). OK, it’s folded into 300 layers, but it’s still steel.
Comparing the vg-10 (rc 59) to the zdp 189 (64) it’s easy. But I admit the difference is most noticeable during sharpening :facepalm: some say they can’t tell the difference between s30v (60) and s90v (63). And remember that the rockwell scale is not linear. An increase from 60 to 66 is not just 10%. Then again, toughness and edge-holding capacity don’t automatically favor the harder steel.