s30v woes

[JoHnYKwSt]

The steel has been out now for 4 years. I really wish someone who knows would inform us as to why this steel causing so many problems. Its like a great big secret or mystery.

 

[EDCeeker]

It doesn't look to me like there's any "great big secret or mystery." It looks to me like perhaps S30V is a bit more difficult to heat treat and temper properly for good performance, is all.

 

[SteelDriver]

The steel has been out now for 4 years. I really wish someone who knows would inform us as to why this steel causing so many problems. Its like a great big secret or mystery.

Crucible might have shipped bad batches of S30V, but the most likely cause for these problems is poor heat treating and overheating the edge by manufacturers. Read some of the relevant threads on S30V chipping and you'll find this to be the general consensus. Better yet, search for posts by Dick Barber, the Crucible metallurgist who developed S30V (his forum handle is Crompal). He addresses this issue directly in more than one post IIRC.

Reading Bladeforums alone might lead you to believe that this is a widespread problem, but you find a scant number of complaints on other boards in comparison. Custom knifemakers using S30V aren't complaining either, and for every complaint of chipping you'll read many more reports of S30V performing well.

 

[Cliff Stamp]

Crucible might have shipped bad batches of S30V, but the most likely cause for these problems is poor heat treating and overheating the edge by manufacturers.

There have been lots of claims made about the source of the problems which make little sense and are contradictory. S30V was promoted for ease of grinding and heat treating over 440C and now both of those are claimed to be the source of the problems even though the exact same asepcts were used to sell the material in the first place. And now we have another from a Crucible rep in that apparently S30V is extremely sensitive to double tempering even after cold treatments. Try to find actual materials data to support that claim.

In general, do you really look to the people who sell you a material for an unbaised perspective on its problems? Why not ask for actual materials data on the defective blades and exactly how they were less than optimal. Was the grain size blown, was there too much secondary carbide precipitation, was there untempered martensite, was there in fact auto-cracks in the martensite from too aggressive a quench, was there a problem with voids in the steel, carbide aggregates, etc. . It can't simply be a batch issue either considering the problem continues to this day and has been widespread over many types of knives.

You would also never expect to see anything near the actual defect rate in reported failures for a number of obvious reasons. How many S30V knives made are actually sold. How many sold are actually used. How many which are used are used enough to determine a problem if it existed. How many people who see a problem are forum posters. How many of those people feel welcome in posting a harsh complaint. Basically every fraction reduction there has an inverse magnification on the reported defect rate. It becomes apparent quickly that the reported defect rate would be small even if the population defect rate is high.

This also doesn't include people who post support simply out of a bias to "help" makers and of course the people who sell the steel directly. Would you really go to the CEO of Coke and ask him for an unbiased opinon on if you should you go with Coke or Pepsi for a major soft drink market. Instead of asking a metallurgist who works for Crucible, ask one who works for Carpenter or one who works for the Japanese cutlery steel manufacturers who are very much anti-vanadium. Also ask one who doesn't work for any steel company which has a significant cutlery interest for an actual unbiased perspective.

-Cliff

 

[SteelDriver]

There have been lots of claims made about the source of the problems which make little sense and are contradictory. S30V was promoted for ease of grinding and heat treating over 440C and now both of those are claimed to be the source of the problems even though the exact same asepcts were used to sell the material in the first place. And now we have another from a Crucible rep in that apparently S30V is extremely sensitive to double tempering even after cold treatments. Try to find actual materials data to support that claim.

First of all, Crucible says S30V "grinds about the same as 440C." This refers to grinding before hardening because S30V is clearly harder to grind than 440C afterwards. Any maker will tell you that it's easier to overheat the edge of a highly wear-resistant steel compared to steels with low wear resistance. Given the same equipment, you have to hold the edge against your belt/wheel longer to get the same amount of metal removal. S30V is one of the most wear-resistant steels that manufacturers use, if not the most.

Ease of heat treating is one thing, getting it wrong is another. O1 is far easier to HT than these stainless steels, you could do it with a torch and eyeball the temps, but if you forget to temper it after quenching and it breaks like glass, are you going to accuse the steel company of false advertising?

Actual materials data on S30V . . . that would be nice. Personally I'd like to see data on 3V, INFI, VG-10, and ZDP-189 as well. But let's be realistic, we're never going to see that from the steel companies. It wouldn't be hard to test the difference between a single vs. double temper. Just ask a knifemaker to grind two identical "mules" and HT them accordingly. Leon and Crucible's observations can thus be independently verified.

It can't simply be a batch issue either considering the problem continues to this day and has been widespread over many types of knives.

The two explanations given are entirely reasonable; knifemakers who don't use S30V and metallurgists from other steel companies would agree that these could cause the problems we're seeing with S30V. Feel free to ask them and let us know specifically what they think. Is there some inherent weakness with the S30V formula or how it's made? The scores of well-performing S30V reports speak for themselves.

 

[bbcmat]

The S30V blade that I have will only go from being extremely sharp (finishing with either 320 or 600 edgePro stone, or green DMT diamond hone) to "big eyes" sharp (cut 1.5"+ out from pinch grip on newspaper,anywhere on the blade) if I use 3 to 5 alternating light passes on my edgepro 1200 grit 10" ceramic steel at an elevated angle. I define "light pass" as only enough pressure to insure the blade tracks the stone and does not lift/skip with my natural hand tremble.

I was able to (inconsistantly) achieve a higher paper press cutting ability using a strop to finish - but never developed a technique to have that edge consistant across the entire cutting surface, or have that edge last under mild abrasion (clean cardboard cutting) as did with the ceramic rod.

Maybe a better stropping technique would change this, but I just have not found it - yet.

MAT

 

[HoB]

Well, I think it is time to finally drop the issue how a steel, S30V in particular, was advertised when it first came out. I think focussing on that is extremely unproductive. Even if the claims that were originally made are incorrect, personally I couldn't care less. Jerry Hossom recently just mentioned that S30V is still labled by Crucible as an air hardening steel, even though it can most certainly NOT be air hardened and produce resonable results.

So, if we finally let the old baggage go, all I want to know is: how to get the best out of S30V and were these problems, that are clearly by now statistically relevant, origin from. Someone, somewhere is doing something wrong and all I care about is to figure out what - not who, just what.

To me a steel is a steel, regardless of what it was advertised as. I want (and quite frankly even expect) a steel to be heat treated and ground in such a manner that it shows its "best properties" (whatever they might be for a given application), and I don't give a rat's a$$ whether that is difficult to do or not. That is not my problem - it is the problem of the person or company that choses to offer a product made from that steel. I don't care whether this steel causes heating elements to burn out, grinding belts to dissolve or mental fuses to blow. I solve that problem simply by paying a premium for it.

So, people let's focus: What is necessary to happen for S30V to perform?

 

[JoHnYKwSt]

I completely agree with everything Hob said. I have already read every thread on S30v. If the steel is more difficult to heat treat, then that somehow needs to be addressed. If the edge is being overheated by the factory then that sounds like a pretty easy fix. Again, this steel is 4 years old -- what's going on?

 

[rosconey2]

i have had or have s30v stuff from benchmade,bradley,strider, camillus and hinderer-
bought over the last year or so-

i do tile for a living,these cut open box's with marble granite and other rock hard stuff inside,once in a while they are used as a scraper-cut platic off skids and hard plastic tie straps-
these take a real beating-

i have yet to have a chip-
they are all edged with my lansky at 25

 

[HoB]

i have yet to have a chip-
they are all edged with my lansky at 25

Small wonder, that is a profile not even fit for an axe.

 

[Cliff Stamp]

Well, I think it is time to finally drop the issue how a steel, S30V in particular, was advertised when it first came out. I think focussing on that is extremely unproductive.

The claims indicate an issue of contradiction which is very relevant when you are citing references.

Jerry Hossom recently just mentioned that S30V is still labled by Crucible as an air hardening steel, even though it can most certainly NOT be air hardened and produce resonable results.

Air hardening means the alloying elements will act to prevent the diffusion based pearlite/bainite and thus allow martensite to form. Consider the TTT curves for 1095 vs D2/A2 for example. Note how 1095 will go into pearlite almost immedately while it is severely delayed in D2/A2 which will form martensite just with an air cool and are thus by defination air hardening. S30V, is very much an air hardening steel by defination, as is 3V.

The gains moving to a more aggressive quench is a higher hardness, usually 1-2 points, and an increase in toughness/corrosion resistance due to prevention of secondary carbide precipitation during cooling. The problem is time/money as well as the risk of direct martensite cracking if you go too aggresssive. The hardness gain is largely irrelevant to most cutlery because makers always draw back from maximum hardness to obtain the golden 60 HRC and the second effect is not so large to even begin to explain the problems seen.

Realize that yes even air hardening steels like A2 can benefit from more aggressive quenches but no this doesn't mean you say they are not air hardening because that isn't what the defination means. Hossom used Bos for years who tempered ATS-34 hot (secondary hardening) and Hossom directly supported this choice of temper. That temper induces significant secondary carbide precipitation (that is what causes the hardening) and thus has a significant negative effect on the toughness and corrosion resistance, see the Hitachi data for details. However, even this still would not explain the extent of problems with chipping in the S30V blades because the magnitude is so great with chipping during sharpening, cutting softer materials, etc. .

S30V is one of the most wear-resistant steels that manufacturers use, if not the most.

S30V is not significantly harder to grind after hardening than D2 and according to your sources they are using so high a temper than it would take a lot of heat to damage it. This also does not explain problems which don't go away with sharpening nor does it explain the problems I have seen with several S30V blades because they are not softened which happens when you significantly draw the temper. Note S30V is actually very temper resistant unlike say 1095 which will rapidly soften as it is overheated, to severely damage S30V, considering the temperatures you listed for tempering you actually have to exceed 650F for a significant amount of time.

Consider for example if someone who used a 650 temper, decided then for whatever reason to do another temper at 750F for one hour. Does the materials data support the claim that the perfomance should be drastically effected? Do you think it is reasonable that someone hand sharpening can generate that much heat or more and hold it for that length of time? When people speak of overheating steels they are generally talking about steels like 1095 which have no temper resistance and thus they soften very rapidly when heated and you only need to go past 325F to actually exceed the temper in some cases.

Ease of heat treating is one thing, getting it wrong is another. O1 is far easier to HT than these stainless steels, you could do it with a torch and eyeball the temps, but if you forget to temper it after quenching and it breaks like glass, are you going to accuse the steel company of false advertising?

The same companies are getting much more consistent results with other steels so that comparion doesn't hold because it implies they would have such systematic problems with all steels.

Feel free to ask them and let us know specifically what they think.

I have, that is why I suggested you do the same.

The scores of well-performing S30V reports speak for themselves.

It speaks for the optimal performance of the steel which was never in contention. It doesn't explain the very high defect rates.

-Cliff

 

[HoB]

The claims indicate an issue of contradiction which is very relevant when you are citing references.
-Cliff

I know it does, but I think it is still not very helpful to continue to lean on this. It is living in the past. What are references good for if they are obviously not relevant anymore. Science is about progress, how does it help progress to know how a steel was advertised as? The steel is out for years now, either the steel can offer some real performance or it will disappear. For anyone interested in performance cutlery should be concerned about how to make S30V perform, otherwise it is just a dead end.

Air hardening means the alloying elements will act to prevent the diffusion based pearlite/bainite and thus allow martensite to form. Martensite just with an air cool and are thus by defination air hardening. S30V, is very much an air hardening steel by defination, as is 3V.
-Cliff

I know and in case this came across wrong this is precisely how Hossom explained it as well. Still, apparently some people tried to air harden it (no forced air)...which didn't work. The procedure suggested by Crucible involves salt baths if I understand correctly.

 

[a223cat]

Has Crucible ever visited us to take on some of our concerns? We are a blade buying population after all.

It could be that the steel is great but not handled properly by heat treaters as they dont have adequate information from Crucible. Shouldnt that be easy enough to correct?

It would seem to me that chipping blades could ruin a makers reputation with the very population that lets him eat.

 

[rosconey2]

Small wonder, that is a profile not even fit for an axe.

hey it works for me,box's and such arent impressed with a radical edge angle-
takes 2 minutes once a week to keep whatever one i use sharp(well i havent touched the hinderer)

 

[a223cat]

Hinderer! thats like saying DONUT to Homer Simpson!

 

[bladeprince]

The steel has been out now for 4 years. I really wish someone who knows would inform us as to why this steel causing so many problems. Its like a great big secret or mystery.

I had an email "converstation" with Darrel Ralph (designer of Camillus CUDA EDC and Maxx, etc.) and he thought it to be heat treatment. He does his own heat treatment and says he has never had a problem or any complaints with his S30V knives. I don't know but thought I'd pass that along.

Regards

 

[SteelDriver]

Do you think it is reasonable that someone hand sharpening can generate that much heat or more and hold it for that length of time?

The edge can heat up very quickly to hundreds of degrees hotter than the rest of the blade, and you don't have to hold it for an hour to affect the temper. If S30V is usually tempered at 400°F like you said, it would be even easier to overheat the edge. S30V also needs to be held for 2 hours minimum at the temper temp. An overheated edge gives the steel there a short and hot temper (no pun intended). Are you claiming that this doesn't affect the hardness or other properties?

The same companies are getting much more consistent results with other steels so that comparion doesn't hold because it implies they would have such systematic problems with all steels.

You missed my point. If they had an incorrect heat treating schedule, they would get consistently bad results. The question is not if companies can heat treat consistently, it's if they know how to heat treat S30V properly.

It speaks for the optimal performance of the steel which was never in contention. It doesn't explain the very high defect rates.

It's not meant to be an explanation of the "very high defect rates," something I don't agree with in the first place. If it's not the steel itself (as it comes from Crucible), then what is the cause? Poor heat treatment practices and post-HT processing (leaving a coarse finish on a notch-sensitive steel isn't a good idea either). Otherwise we'd be seeing the same "widespread" reports among S30V customs regardless of maker.

Has Crucible ever visited us to take on some of our concerns? We are a blade buying population after all.

Dick Barber (the developer of S30V), Ed Severson, and Scott Devanna have all posted at BF. They said Crucible is analyzing some of the chipped blades to figure out what went wrong.

 

[Cliff Stamp]

[overheating]

Are you claiming that this doesn't affect the hardness or other properties?

No, I am stating that those who used S30V and have had problems have used very hard to grind steels like D2 and thus they would be well familiar with how to grind such steels. I also noted that you have to exceed the tempering temperature significantly in order to soften a steel and that this will not have a dramatic effect if the steel has significant temper resistance, you are essentially just giving it a very short temper at that elevated temperature and you noted that S30V has a long temper time which again means it is temper resistant. Examine the temper responce of S30V to see what kind of temperatures would be required to produce a significant softening, the data is in the spec sheet.

You missed my point.

No, your point was illogical. You cited an example of a un realistic systematic defect, do you really think companies are deciding not to temper S30V but are for VG-10 - that is obviously absurd. You would need to argue that the same realistic process applied to both would produce drastically inferior results for S30V, i.e., it is much more demanding. However, P/M in general, not simply CPM's, but all P/M's are actually easier to heat treat and more forgiving because of the finer and more consistent structure. Note for example Wilson's rehardening of S30V blades without any annealing/normalization. Under a given protocol you would expect problems to arise in similar ingot steels long before P/M's, not the opposite.

Otherwise we'd be seeing the same "widespread" reports among S30V customs regardless of maker.

No it doesn't. This assumes that the same percentages I noted in the above hold for customs and production blades and this is obviously not the case. You would expect a massive increase in reported problems for production blades even if both populations had exactly the same defect rate.

It is living in the past. What are references good for if they are obviously not relevant anymore.

Those issues are not past HoB, many are in fact general properties of P/M's. As well those same documents still exist and have not been changed so it is still very much being promoted the same way.

Still, apparently some people tried to air harden it (no forced air)...which didn't work.

No metallurgist (publically) would ever say that forced air in front of a fan like Wilson does would have such a dramatic effect on the small cross sections seen in cutlery in regards to through hardening an air hardening steel. Ask for the TTT diagram for S30V and show that to an independent metallurgist and ask them if that is an air hardening steel. As Crucible notes for S30V, atmosphere cooling will induce a 1-2 HRC loss in hardness over oil. Thus for example 1950+air/cold+400 F would give 59 HRC for S30V. Few people are actually running it significantly harder.

The procedure suggested by Crucible involves salt baths if I understand correctly.

To maximize hardness yes, but again this is nothing particular to S30V or P/M's, and it is a small effect usually you are talking about 1-2 HRC points. It also doesn't seem to be sensible to be really adamant to mandate this and then draw the temper back to what you would get with air cooling. This is why Wilson doesn't use more aggressive quenches such as oil on S30V because he gets the hardness he desires with forced air, actually harder and he has to draw it back. Again, I am not saying that air hardening is optimal, but it is not the case that it "won't work" or explains the defects seen.

Note that if you really want an optimal blade you have to do more involved heat treatments which involve multiple cold/tempers + water quenching after the temper. This minimizes retained austenite and carbide precipitation, see Landes notes for details. These however are again small refinements and not really something you would expect in production blades. You are also not likely to notice the difference they would make unless your edge angles were both very low and your tolerance for sharpness was very high.

-Cliff

 

[searcher]

Multiple tempering is more critical for upper temperatures because there is significant transformation of the austensite to martensite because of carbide precipitation which effects the Ms point and thus induces martensite to form in the cooling after tempering. A single temper then leaves this martensite untempered. However S30V is usually tempered very low around 350F - 400F which doesn't have the same effect on the steel. Nor in general are the results so drastic to explain the performance seen such as steels chipping on carboard, plastic, vegetation, etc. . No one would argue that going from single to double temper, especially with low temperatures would induce such a change in the material properties of the steel.

-Cliff

What does this mean? What upper temperatures are you talking about? Carbide precipitation does not cause transformation of austenite to martensite. What are you trying to say effects the Ms (upper transformation temperature?) point, carbide precipitation? What about different Ms points induces martensite to form in the cooling after tempering?

I usually find that if the steel producer recommends multiple tempering it is prudent to follow their instructions.

The following is a quote from the Tool and Manufacturing Engineers Handbook third edition p23-26:
"Multiple tempering will often correct for poor hardening practices, which result in the presence of variable amounts of retained austenite. Multiple tempering is more effective than a single tempering operation for highly alloyed steels. Double or triple tempering is advisable for air-hardening, hot-work, and high speed steel tools. The first treatment tempers the martensite formed during quenching and conditions some of the retained austenite for transformation to martensite during cooling to room temperature from the tempering temperature. The second treatment is then necessary to temper the martensite formed during the first tempering operation. The third tempering, when used, further decreases the amount of untempered martensite still remaining, thereby improving mechanical properties"

 

[HoB]

[overheating]
Those issues are not past HoB, many are in fact general properties of P/M's. As well those same documents still exist and have not been changed so it is still very much being promoted the same way.
-Cliff

On this one I have to disagree. The reason why I think it is a past issue in so far as you can now, after however many years, advertise the steel anyway you like and you are not going to fool anybody in the trade. So my contention is that it is by now completely irrelevant how the steel is advertised as.

In the end I think it is important not to let the goal out of sight. From what I have seen, and from the positive reports I have read, I have to come to the conclusion that S30V is a pretty good product for many applications (knife wise). It would be a shame to have it disappear from the market, because the issues with it do not get solved and that because we fight a war over false claims that someone made somewhere about the steel.

As to the quenching. I have to defer to you on that as I don't know enough about it. From what I have read, my impression was that the differences between a piece that is allowed to cool slowly and one that is quenched/cooled with plates, is FAR greater, but my sources are only snippets off the internet. I don't remember which schedule Phil Wilson uses and he might be disprove my theory immediately, but I begin to wonder if this isn't the source (or one of the sources) of the problem: that makers are let to believe by the existing data sheets and the composition of the steel that an air quenched sample should be fine, while in fact it is not, and the differences are much greater than you just said. But I don't know. I am way out of my depth and this is pure speculation on my part. It is just that I have read on multiple forums by multiple people that they had problems with S30V and 3V before they employed cooling plates or other means of quickly pulling of heat.