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High-Performance Blades Sharing ideas for getting the most out of our steel.

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  #1  
Old 09-26-2004, 01:09 AM
Ssj2 Ssj2 is offline
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whats the toughest stainless steel?

I have read about alot of stainless steels and from what I see there are 3 toughness champs ats34/154cm, bg-42 and s30v. I wanted to know out of these 3 at the same hardness whats the toughest? Also if theres a tougher stainless steel out there then these I would like to know. I know theres 420, 440abc, s60v and s90v but from what I read they are lacking in the tough department with the excepion of maybe 420 but it lacks in every thing els wear resistance, edge retenion etc

Last edited by Ssj2; 09-26-2004 at 05:13 PM.
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  #2  
Old 09-26-2004, 12:24 PM
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mete mete is offline
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154-cm and S30V are made by www.crucibleservice.com and you can find the info there. BG-42 is made by www.timken.com but they don't list toughness figures[ it's a bearing steel. They are all fine steels for knives and they require careful heat treatment and picking the right HT will maximize the toughness.
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Old 09-26-2004, 03:22 PM
mdagley mdagley is offline
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At the same hardness it's been my experience that S30V is considerably tougher than either ATS34/154CM and BG42.


Mike
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  #4  
Old 09-26-2004, 05:22 PM
Ssj2 Ssj2 is offline
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Thanks for your replys guys. I just recently read that s30v is as tough as a2 tool steel. I'm not sure how tough that is but most people say it's tougher then most stainless, except this one web site http://www.specialtyblades.com/mater...ol_steels.html. They say ats34 is a little bit tougher so I'm a little confused here.
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Old 09-26-2004, 06:42 PM
mdagley mdagley is offline
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It's been my experience that ATS34 is not nearly as tough a steel as S30V. I have made a few of each (as close to identicle as I can) all of the same Rc ~60. In every case it took a heck of a lot more effort/abuse to damage the S30V blades. S30V also takes an equal or better edge and in my chopping and cutting tests holds it far better.

The only negative thing I can say about S30V is that it takes more time/effort to reach an equal level of finish as ATS34/154CM, BG42---and I, for one, do not ever wish to have to try to mirror polish S30V again. There may be someone out there that has developed a better method of polishing, but the ways I know just take far to long to get there.

If my aging memory is correct, Blade magazine ran an article where the late Rob Simonich torture tested an S30V blade to destruction. It was amazing what it took for him to break the blade.

Mike
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  #6  
Old 09-27-2004, 05:27 PM
Ssj2 Ssj2 is offline
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Thanks Mike I appreciate your ansers, it sounds like s30v is the toughest stainless steel there is.

I wonder just what makes one steel tougher then another. I thought it had to do with the alloying elements that are within the steel, for example ats34 is tougher then 440c because it has molybdenum in it and less cronium. If this is the case tho then ats34 should be tougher then s30v because it has the same amount of cronium but has more molybdenum. So this can't be because s30v is tougher. Does carbon content have any thing to do with toughness? can any one shed some light on this subject?
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Old 09-27-2004, 06:59 PM
mdagley mdagley is offline
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I'm not real sure about how all the different elements may effect toughness myself. I do know (at least I think I do) that the higher the carbon content is the more brittle the steel can be.
One of the things S30V has going for it it it's super fine grain structure which does make a big difference in toughness.
Others will be able to answer the finer points of this far better than I can. Perhaps Crucible Service Center customer service people can give you a better understanding of this. Just my thoughts.............

Mike
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  #8  
Old 09-28-2004, 12:05 AM
Ssj2 Ssj2 is offline
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If higher carbon content means less toughness then shouldn't ats34 along with a lot of other stainless steels be tougher then s30v? S30v has 1.45C while ats34 only has 1.05.

I went to crucibles data sheet on s30v and its wierd because they have two seperate charts stating its toughness. The first chart is a bar graph saying s30v is the same toughness as d2 tool steel and 154cm the second chart says its 4 times tougher then 154cm and 440c. I'm still confused. Here's the web page www.crucibleservice.com/datash/dsS30Vv4b.pdf

Last edited by Ssj2; 09-28-2004 at 02:06 AM.
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  #9  
Old 09-28-2004, 06:51 PM
mdagley mdagley is offline
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Higher carbon content equaling less toughness is only a general rule of thumb. Where S30V cheats this rule is through it's extremely fine grain structure (at least that's the way it's been explained to me).
The charpy toughness graph on Crucible's web site shows S30V being significantly tougher than eithre 154CM or D2. This pretty well mirrors what I have seen in my own testing. The other graph I saw there is on edge rentention, again showing S30V as being much better than either 154CM or D2. This is also pretty much what I have seen in actual testing.
Remember that 154CM is essentially the same steel (chemicaly) as ATS34 so what is said for the toughness/edge retention for one is generally true for the other.
From what I have seen of S30V, it flat out beats 154CM/ATS34, D2, and BG42 for toughness and edge retention. Though BG42 is not far behind in edge retention.
Again, there is a lot to the chemical makeup and processing of steels that is way beyond my meager knowledge and experience, Crucible's customer service can probably answer your questions far better than I can.
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Old 09-28-2004, 08:29 PM
Ssj2 Ssj2 is offline
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Thanks again, I guess I'll go to Crucibles custumer service for the rest of my questions on toughness of there steels.

One more thing I was wondering about is just what good carbon is in a steel. I know carbon turns iron into steel so I guess it makes it stronger but if more carbon generally means more brittle, I don't understand why any one would put more then one percent carbon in there steel. The reason I say 1% is because with 1% you can get up to rc 62 in a steel and almost no body hardens there steel higher then that.
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  #11  
Old 09-28-2004, 08:46 PM
fitzo fitzo is offline
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The competition of alloy elements for carbon makes a difference. In plain carbon steel, approximately 0.84% Carbon is called eutectoid, just enough carbon for the iron for maximizing hardness. It's more complicated than that, even, but that's a start.

Last edited by fitzo; 09-28-2004 at 08:48 PM.
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Old 09-28-2004, 11:23 PM
Ssj2 Ssj2 is offline
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So in plain carbon steels you need .84% for maximum hardness but when you have alloying elements in the steel you need more carbon to get it to the same hardness because the elements take up some carbon?
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Old 09-29-2004, 03:18 PM
fitzo fitzo is offline
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One of the metallurgists will hopefully venture a more technical explanation. When you add in elements like chromium, molybdenum, tungsten, silicon, and vanadium, that can also form carbides, they compete for the available carbon. The carbon percentage has to be increased to supply all the necessary carbon to make the desired level of carbides of the various elements. I don't know what the proper metallurgical term is; in organic chemistry we call it "stoichiometry". When you add in these additional elements, they have much higher carbide hardnesses than plain steel, which further complicates the equation. The balancing of the various elements in the formulation control capabilities of final heat treat characteristics and performance. It is not as simple as only the carbon percentage, it becomes very complex.

Sorry I can't explain it better, but I'm sure we'd both prefer it that you don't get misinformation.
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Old 09-30-2004, 01:46 AM
Ssj2 Ssj2 is offline
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Thanks Fitzo.

I guess to wrap this up can every one tell me what they think the toughest stainless steels are based on there expirence starting from best to worst.

based on what I've seen and read this would be my line up.

1. s30v
2. bg-42
3. ats34/154cm
4. d2 (I include d2 just because it's almost stainless and I would like to know what yall think of its place in the world of stainless steel toughness.
5. 440a
6. 440b
7. 440c
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  #15  
Old 09-30-2004, 06:16 AM
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Mark Williams Mark Williams is offline
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