CPM S30V for bush knife?

[jeffrice6]

Would S30V work well for a tough bush knife, say 5" x .180 thick ~ or should I be looking at another stainless?

 

[JasonSCarter]

that'll work just fine, however for ease of sharpening I'd switch to carbon steel. but if Stainless is a must 44c might be a lil easier sharpening

 

[cotdt]

Sure why not, but .180" is a bit thick. I assume you will use a Scandi grind and that will be tough to sharpen. Lots of steel to grind.

 

[Nathan the Machinist]

CPM S30V combines relatively poor edge stability with fairly bad sharpenability. It is good for an obtuse edge subjected to abrasive wear on a low maintenance knife such as an EDC used to break down cardboard etc.

My preference for an outdoor knife in stainless would be lower carbon, lower carbide for enhanced edge stability and toughness and faster sharpening. I think that CPM 154 would be better, or even perhaps something like Sandvic 13C26 which is fairly low on chrome and said to behave more like a carbon steel.

 

[wnease]

I'm having pretty good results with S30V scandi at about 22 degrees, RC 60, lower sustenitizing temps than crucible recommends plus LN cryo

Jerry Hossom says edge stability improves with the quality of edge finish in S30V, I use a 1200x diamond followed by 2 grits of hard strop

my 440c blades will not come close to this edge stability at RC 58

 

[Jerry Hossom]

CPM-154 and S30V have the same Chromium content and about the same levels of Carbon so the carbide content is about the same. The advantage of S30V is the Vanadium which are very small carbides and add a lot to edge holding. Generally speaking Edge Holding is inversely proportional to Ease of Sharpening. Using a small belt sander for sharpening makes getting a good edge on any and all steels the same - dead easy. (On that subject, I know many have expressed concern about heat being generated by sharpening on a belt. That only happens if you are entirely careless. I test the edge after every couple passes to see if it's getting hot. S30V is tempered at 600F and long before I get there the sound of my own screams will usually tell me I'm going too far. That happens at about 212F. I might point out that S30V actually gets harder above 600F, up to 900F, at the expense of some corrosion resistance. By contrast tool steels generally start losing their temper at 400F.)

If you look at photomicrographs of S30V, CPM-154, AEB-L and 13C26 you'll see that the carbide sizes aren't that much different. That's due to the particle metallurgy used for S30V and CPM-154. D2, 440C and 154CM have much larger carbides. S30V is a good steel, but must be heat treated properly and I think many of the first factory production batches weren't, so the steel got a bum rap at the beginning. Most have now learned how to handle it. In any case the problem was not the steel, but how it was treated. That's one thing that makes knife steel evaluations difficult. You never really know if problems are the result of the steel itself, how it's heat treated, edge geometry or any combination of these.

On the edge polishing issue, edges in any steel are more stable if they are polished. Rough edges are full of stress risers by definition. That's where cracks and chips form.

I've made large choppers of S30V and chopped through dry hickory without damage. IMO, that's sufficient toughness for most knives.