M390 vs. M4 vs. s30v

[guitarhead1]

OK....are m4 and m390 that much more superior to s30v?? How?? Thanks. And let me throw Benchmade's 1095 steel into the mix. How does it compare to the other 3 steels? Many really good fixed blades come in 1095. Why? What does it offer. Chris Reeve has a good reputation. His fixed blades come in S30V. Why not one of the others if they are superior?

 

[Noctis3880]

First thing to note:
S30V is usually heat treated to Rc 57-59 range, and sometimes in the Rc 59-60 range. That is how hard the steel is and can affect edge holding and wear resistance.

M4 is somewhere in the Rc 63-65 range and is much harder than other steels. Stain resistance isn't that much higher than 1095 though.

M390 is said to have slightly better edge holding than M4, and is stainless on top of that. Hardness is said to be Rc 60-62, but I feel it's closer to Rc 60-61 unless it's custom heat treated.


1095 offers a level of toughness that most stainless steels simply aren't physically capable of. This is why you don't see stainless steels in any good katanas or swords. The ones that use them typically break easily and causes injuries because of it(if you haven't already seen that video). However, most stainless steels would be tough enough for much smaller fixed blade knives. Though you won't see 1095 used in swords either since the high carbon content would make it more brittle than something like 1060 with a lower carbon content. In a knife, it offers excellent toughness, hardness is typically Rc 58-60, and it's easy to sharpen without a lot of carbides.

I can't really say why Chris Reeve runs S30V so soft in his knives. Some say it's a cost saving measure. Some say it's to make it easier to sharpen. The more wear resistant a steel is, the harder it is to sharpen.

As for why Chris Reeve doesn't use a "better" steel... One reason might be domestic availability. Some makers want to support people at home, and so buy steels from the U.S. I believe that to be the case with Rick Hinderer as well. Another reason is that it would take time and money to figure out how to consistently heat treat a brand new steel type. And while it seems obvious that the "better" steel should be used, again more wear resistance means more difficulty sharpening.

Though my personal opinion is that someone should take a run of their flagship knives and offer a variation of it using "higher-end" materials, all the while keeping the regular version in production. I could see the Sebenza being much improved with a full-anodized finish on their titanium handles and CPM154 blade steel at Rc62.

 

[DennisStrickland]

thanks noctis for all the great info plus the patience to reply to such an involved question. my experience certainly supports your summations. new guys are'nt generally aware of all the ups & downs of the atomic alloys. in addition some makers can tweak the simpler alloys to very high rockwells w/o brittleness. sniper blades is one of those. also fowlers work with 52100 is classic.---dennis

 

[Buffalohump]

Bottom line: a tool steel will take an edge easily and cut like the dickens. However it will also stain and rust if neglected.

A stainless steel will take an edge less easily and cut like the dickens. It wont stain or rust if neglected as easily as tool steel.

So pick your poison. Many prefer stainless on folders and tool steel on fixed blades. I concur.

However, if you are meticulous with your knives and clean them religiously after use, there is no reason you cant enjoy the wonderful edge holding and ease of sharpening offered by a steel like CPM-M4 for example. Or ZDP-189 which I happen to like very much.

Or even a 'lesser' steel like 1095. If you are prepared to live with staining or patina on your blade that is...

My take on S30V is that it is a middle ground steel that works across a broad spectrum. Its stainless, is 'relatively' easy to sharpen and it takes a reasonably good edge. There's nothing wrong with it, but like a lot of things that tries to be all things to all men, it compromises in certain areas, like edge holding.

Perhaps S35VN will be a better solution. However, from what I have seen, we should be looking closely at CPM154 as well...

As for M390 my experience with it is limited. From what I have seen so far it is good and hard... however, the company that uses it the most - Benchmade - tends to put a bit of a crap edge on their knives, so unless you are prepared to reprofile, its a bit of a non-starter. Otherwise I think diamond sharpeners may be in order.

Now if Spyderco were to start using it..... boy, then we'd really see something.

So far I like CPM-M4 the best. Especially if coated with a good rust inhibitor...

 

[Big Mike]

Talking carbon steels:

CPM M4 offers great edge retention (one of the best) but is not that tough.

I also like other tool steels (like A2 and D2) for their balance of toughness and edge retention.

The 10XX steels also offer a good balance, 1095 being the top of the class for a long wearing edge; but they offer less stain resistant then their tool steel counterparts.



When it comes to Stainless:


CPM S30V is a good steel, I'd rate it better then most of the other Stainless steels, with a properly supported edge it can offer a good balance of toughness and edge retention...

Perhaps S35VN will be a better solution. However, from what I have seen, we should be looking closely at CPM154 as well...

...but I agree with BH, CPM S35VN and CPM 154 look to be new top dogs for those demanding stainless knife blades.




Big Mike

 

[Ankerson]

OK....are m4 and m390 that much more superior to s30v?? How?? Thanks. And let me throw Benchmade's 1095 steel into the mix. How does it compare to the other 3 steels? Many really good fixed blades come in 1095. Why? What does it offer. Chris Reeve has a good reputation. His fixed blades come in S30V. Why not one of the others if they are superior?

S30V is an excellent general purpose steel and has served many for along time now. S30V seems to be at it's best at 60 HRC for edge holding, but most production companies get it hardened lower than that at 58-59 HRC.

M390 is new to the knife world so it hasn't had time to gain general acceptance yet with the production companies. It's very strong, stain resistant and hold an edge very well at 60-62 HRC. Production blades will be in the 60 HRC range, that is on the low side IMO, should be 61 HRC.

M4 isn't stainless, but will hold an edge well and it's strong, it's usually around 62 - 64 HRC in production blades.

Not really sure why Chris Reeve does what he does, but I am sure he has his reasons.

 

[dsmegst]

OK....are m4 and m390 that much more superior to s30v?? How?? Thanks.

CPM-S30V:
Carbon (C) 1.45
Chromium (Cr) 14.00
Molybdenum (Mo) 2.00
Vanadium (V) 4.00

CPM-M4:
Carbon (C) 1.40
Chromium (Cr) 4.00
Manganese (Mn) 0.30
Molybdenum (Mo) 5.25
Silicon (Si) 0.55
Sulphur (S) 0.06
Tungsten (W) 5.50
Vanadium (V) 4.00

M390:
Carbon (C) 1.90
Chromium (Cr) 20.00
Manganese (Mn) 0.30
Molybdenum (Mo) 1.00
Silicon (Si) 0.70
Tungsten (W) 0.60
Vanadium (V) 4.00

Carbon (C)
• Increases edge retention and raises tensile strength.
• Increases hardness and improves resistance to wear and abrasion.
Chromium (Cr)
• Increases hardness, tensile strength, and toughness.
• Provides resistance to wear and corrosion.
Manganese (Mn)
• Increases hardenability, wear resistance, and tensile strength.
• Deoxidizes and degasifies to remove oxygen from molten metal.
• In larger quantities, increases hardness and brittleness.
Molybdenum (Mo)
• Increases strength, hardness, hardenability, and toughness.
• Improves machinability and resistance to corrosion.
Silicon (Si)
• Increases strength.
• Deoxidizes and degasifies to remove oxygen from molten metal.
Sulfur (S)
• Improves machinability when added in minute quantities.
Tungsten (W)
• Adds strength, toughness, and improves hardenability.
Vanadium (V)
• Increases strength, wear resistance, and increases toughness.

(Above information is taken from the Spyderco website: http://www.spyderco.com/edge-u-cation/index.php

And let me throw Benchmade's 1095 steel into the mix. How does it compare to the other 3 steels? Many really good fixed blades come in 1095. Why? What does it offer.

1095:
Carbon (C) 0.90-1.03
Manganese (Mn) 0.30-0.50
Phosphorus (P) 0.04
Sulphur (S) 0.05

Non-stainless carbon steel like 1095 is very strong and tough, can take an awesome edge, and is easy to sharpen. It sacrifices corrosion resistance for toughness and sharpness.

Chris Reeve has a good reputation. His fixed blades come in S30V. Why not one of the others if they are superior?

To quote Chris Reeve from his sub-forum: (He was answering questions primarily regarding the blade steel choice for the Sebenza but I think it's still relevant.)
"· My choice to change our folding knife blade steel to S30V was thoroughly thought through, as was the selection of RC hardness 58-59. I was privileged to be involved in the development of S30V with the metallurgists at Crucible Steel – they asked what attributes I wanted in a steel and they delivered. At RC 58-59, the blade will hold a good edge and will be easy enough to sharpen. One of our tests resulted in S30V cutting 14,000 linear inches of e-flute cardboard before notable edge wear against 12,000 for BG42. I have been completely satisfied with the performance of S30V."


The problem with comparing one steel to another is that you don't know how they are heat treated and ground. Even a small difference in heat treat can make or break a knife blade. The physical shape like blade profile, grind type and edge angles can add even more variety to the mix. Still, the information posted above should give you a place to start as a reference point.

 

[kreole]

Talking carbon steels:

CPM M4 offers great edge retention (one of the best) but is not that tough.

I also like other tool steels (like A2 and D2) for their balance of toughness and edge retention.

The 10XX steels also offer a good balance, 1095 being the top of the class for a long wearing edge; but they offer less stain resistant then their tool steel counterparts.



When it comes to Stainless:


CPM S30V is a good steel, I'd rate it better then most of the other Stainless steels, with a properly supported edge it can offer a good balance of toughness and edge retention...





...but I agree with BH, CPM S35VN and CPM 154 look to be new top dogs for those demanding stainless knife blades.




Big Mike

It's pretty tough, better than D2 and almost at A2 levels according to Crucible:

Considering it's tougher than D2 and has much better edge holding, I'm surprised you don't like it. I like D2 a lot (more than S30v, for example), but not as much as M4.

 

[hardheart]

That toughness is also at a hardness about 3-4 points higher than the A2. CPM M4 has an excellent set of properties.

 

[Big Mike]

It's pretty tough, better than D2 and almost at A2 levels according to Crucible:

Considering it's tougher than D2 and has much better edge holding, I'm surprised you don't like it. I like D2 a lot (more than S30v, for example), but not as much as M4.

Don't get me wrong, I love and use all three, in fact my M4 Mule is my most used knife lately, that thing just keeps on cutting.





They're all plenty tough for me. :thumbup:




Big Mike

 

[Toyz]

I like them all - I just don't use knives hard enough to be able to clearly see a lot of the differences. I'm also not great at sharpening, so I constantly try to touch up my blades so they do not get dull.

I like CRK S30V - I have an Umnumzaan and Sebenza and the steel holds up well for what I use my knives for.

CRK is switching over to S35V over the next 12 months - and it is reported that it might offer 15-20% more toughness that S30V - but I probably wouldn't notice the difference with my usage.

Some argue that the steel type is only one part of the equation - grind, shape and heat treat also seem to play a role in the overall performance of a knife blade.

I use the new steels as part of the justification to myself as to why I need to buy another knife.

 

[Ankerson]

CRK is switching over to S35V over the next 12 months - and it is reported that it might offer 15-20% more toughness that S30V - but I probably wouldn't notice the difference with my usage.

Not sure who is saying it's 15 to 20% tougher, but they are dead wrong on that.

Link to the S35VN data sheet, notice the toughness chart.

http://www.crucibleservice.com/PDFs/\DataSheets2010\dsS35VNrev12010.pdf

Some reports are coming in that edge retention is a little better, but that's from custom makers so I doubt we will see much of a real difference in production knives over S30V.

If they are putting out S35VN soft like some seem to be then I don't see the reason to even bother changing over as I doubt that most end users will see any difference.

 

[dwarthog]

Not sure who is saying it's 15 to 20% tougher, but they are dead wrong on that.

Link to the S35VN data sheet, notice the toughness chart.

http://www.crucibleservice.com/PDFs/\DataSheets2010\dsS35VNrev12010.pdf

Hmmm, I must be missing something when reading that data sheet.

From the first page.

Substituting niobium carbides for some of the
vanadium carbides makes CPM S35VN about 15-20% tougher
than CPM S30V without any loss of wear resistance. CPM S35VN’s
improved toughness gives it better resistance to edge chipping.

 

[hardheart]

the increase on the chart from 10 to 12 is a 20% increase, plus it was Crucible themselves who mentioned it.

 

[Ankerson]

the increase on the chart from 10 to 12 is a 20% increase, plus it was Crucible themselves who mentioned it.

Yeah I read that, but their own chart doesn't show that difference when compared to S30V, more like maybe 5%.

So I am not buying it at this point as it's way too early to tell.

 

[Tostig]

My MPR is M390, yea BM puts WAY too much of an obtuse edge on some of their offerings.
After a hand/stone reprofile it cuts very well and a cardboard strop brings the edge back some until I get home to my stones. but still cant fully test is slicer abilities until I get it reground by Mr. Southard.

I think time will tell M390 to a top class steel along with the others.

Tostig

 

[hardheart]

Yeah I read that, but their own chart doesn't show that difference when compared to S30V, more like maybe 5%.

I just checked with GIMP, 45 pixel height for S35VN, and 37 pixel height for S30V. So no worries, that's still a 21.6% difference in the bar graph as well.

 

[RandomAyes]

.......

 

[Ankerson]

I just checked with GIMP, 45 pixel height for S35VN, and 37 pixel height for S30V. So no worries, that's still a 21.6% difference in the bar graph as well.

I am not seeing that.....

Not really worth debating it though when there aren't any real numbers there.

Even if it might be 10-15% difference from S30V it won't matter one bit if the production manufactors aren't going to take advantage of the added toughness.

S30V is already very tough when run at around 58 HRC so running S35VN at the same hardness won't really make any noticable difference for most of the users. So the point of changing makes no since at all unless they are going to make choppers out of it. For folders I don't see the point at all unless they are going to raise the HRC to take advanage of it, they might as well stick with S30V if that is what they are going to do.

The steels are just too close to each other and if the advange of S35VN is that they solved the chipping issues of S30V when run around 60 HRC then they could run it at a higher HRC than S30V, if they don't then it's a waste.

They would be better off using CPM-154 and running it at 61 HRC....

That's the real point I am trying to make.

 

[Buffalohump]

Jim I'm guessing here but my feeling is that they are changing over purely to eliminate concerns about S30V chipping. I have personally not experienced this chipping but I guess if the rumours are persistent enough it can become a real problem.... so I guess with that 10 - 20% increase in toughness, or whatever it is, they can say presumably kiss any chipping issues (real or imagined) goodbye and put that boogeyman to bed.