S30v empressions

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Do you think that the actual toughness is less than CPM has tested? I've chopped with large D2 and 440C knives with no issues yet (I admit they are not the ideal steels for a chopper, but this is the old how tough is tough enough argument), and they are less tough than S30V. I think the failure is less about any inherent lack of toughness associated with S30V, and more about something else.
 
Broos said:
Do you think that the actual toughness is less than CPM has tested? I've chopped with large D2 and 440C knives with no issues yet (I admit they are not the ideal steels for a chopper, but this is the old how tough is tough enough argument), and they are less tough than S30V. I think the failure is less about any inherent lack of toughness associated with S30V, and more about something else.
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It could be the thinner than usual angle I used at 13 degrees per side. It might hold up just fine at 20 degrees per side, but still, my carbon/tool steels had no issue at the thinner angle. I'm pretty sure the S30V was heat treated correctly as it was done by a recognized professional heat treater.

According to Crucible, the toughness of S30V is the same as 440C and D2 (25-28 ft. lbs). S30V does have higher lateral toughness but each steel has its own lateral toughness peak at specific hardness points. It just so happened that they tested 58 rc. At 60 rc, D2 is tougher than S30V.
 
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What type of cutting is toughness much of a factor? I'm guessing it may effect knives with exstreme thinness and hardness.
 
db said:
What type of cutting is toughness much of a factor? I'm guessing it may effect knives with exstreme thinness and hardness.
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Cutting copper wires, coated Tylenol tablet, etc. Most stainless steel knives will have trouble with these with anything less than 13 degrees per side, regardless of the hardness. If you soften the steels to say... 55 rc, their "through the grain" impact toughness goes up yet they will still chip/dent in actual use.

The carbon steels are much tougher at the knife edge, despite what the numbers might say. That's why my dedicated pill cutter is 52100 @ 63 rc (10 degrees per side), because the edge can take all the pills I throw at it w/o chipping, and the thing just makes perfect smooth cuts forever.
 
I did think that hardness did have alot to do with how a edge would hold up, and the toughness of a steel wasn't much of a factor. Just as an exstreme exsample a very tough steel at a low hardness, say rc 40, will get a damaged edge fairly easily. Then lets say a low tough steel at a high hardness will have an edge that will take a fair amount to damage. Sure the damage will be different rolling for the softer and chipping for the harder one but the softer edge will damage easier. Does that sound correct?
 
db said:
I did think that hardness did have alot to do with how a edge would hold up, and the toughness of a steel wasn't much of a factor. Just as an exstreme exsample a very tough steel at a low hardness, say rc 40, will get a damaged edge fairly easily. Then lets say a low tough steel at a high hardness will have an edge that will take a fair amount to damage. Sure the damage will be different rolling for the softer and chipping for the harder one but the softer edge will damage easier. Does that sound correct?
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That matches my experiences as well. If hardness is the goal, a good knife steel would be able to obtain high hardness (62+ rc) without being brittle. 154CM becomes chippy at 62+ rc, and S30V same problem. VG-10 is actually good at 62 rc, Japanese kitchen knives use this, it may not be tough but it's not chippy so performance is very good.
 
CPM D2 at 62 RC has really impressed me compared to S30V at 59 RC when comparing my 2 Spyderco Militarys. The CPM D2 takes a sharper edge easier and holds it longer when cutting side by side. No real numbers to report, just greater ease of sharpening and holding a shaving edge longer than S30V in identical blades. Until recently I didn't realize how hard the CPM D2 Millie was, but it certainly explains a lot as to why I liked it's performance over S30V. For the cutting I did toughness wasn't a factor as neither steel chipped or rolled. It would be interesting to compare some 60.5-61 RC S30V (ive heard it gets chippy past 61 RC) to CPM D2 at 62 RC, as well as see some toughness charts on CPM D2. Maybe I can get my S30V Millie re heat treated to 61 RC to see if it is a better match. When I bought my CPM D2 Millie it cost the same as the S30V version and I consider it to be one of the best bargains in a knife that I have ever bought. I'll be the first to admit I'm not a huge fan of S30V, but it is no slouch in my Manix or Military. CPM D2 just performs that much better for me in all areas (though S30V should be better in corrosion resistance, but in northern Cali I've had no issues with corrosion).

Mike
 
gunmike1 said:
CPM D2 at 62 RC has really impressed me compared to S30V at 59 RC when comparing my 2 Spyderco Militarys. The CPM D2 takes a sharper edge easier and holds it longer when cutting side by side. No real numbers to report, just greater ease of sharpening and holding a shaving edge longer than S30V in identical blades. Until recently I didn't realize how hard the CPM D2 Millie was, but it certainly explains a lot as to why I liked it's performance over S30V. For the cutting I did toughness wasn't a factor as neither steel chipped or rolled. It would be interesting to compare some 60.5-61 RC S30V (ive heard it gets chippy past 61 RC) to CPM D2 at 62 RC, as well as see some toughness charts on CPM D2. Maybe I can get my S30V Millie re heat treated to 61 RC to see if it is a better match. When I bought my CPM D2 Millie it cost the same as the S30V version and I consider it to be one of the best bargains in a knife that I have ever bought. I'll be the first to admit I'm not a huge fan of S30V, but it is no slouch in my Manix or Military. CPM D2 just performs that much better for me in all areas (though S30V should be better in corrosion resistance, but in northern Cali I've had no issues with corrosion).

Mike
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It's too bad that CPM D2 has been discontinued in its short life. Crucible's website never even acknowledged its existance. They say that its corrosion resistance is better than D2's, making it basically a stainless steel.

S30V at 61 rc is a beast. Lone Wolf Knives uses it at this hardness. With the low temper, 61 rc is as hard as S30V gets without becoming chippy, according to my conversation with Mr. Wilson. However, 62+ rc should not be an issue if the high temper (975F) is used. You sacrifice some corrosion resistance, but I would highly recommend you try it rehardened to this (because I am interested in the results).
 
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