Consensus appears to be that it's actually a 440A equivalent
I asked Gerber about the blade steel in the Mini Swagger, a new framelock with a street price of about $20. The catalogue describes the blade only as "stainless steel."
I got this response:
"Thank you for contacting Gerber Blades. The Mini Swagger is comprised of 7Cr17MoV (Chinese version of the 440C) Stainless Steel with a black Titanium Nitride PVD Coating. It is most comparable to 440C Stainless Steel."
I have some inexpensive Chinese blades, including Spydercos, Sanrenmus and Kershaws, but I am unfamiliar with this particular steel.
Does anyone have any experience with it?
Consensus appears to be that it's actually a 440A equivalent
Definitely not comparable to 440C, I'd agree with kreole in saying it is pretty comparable to 440A
The 9cr18mov sounds pretty decent, but this stuff, not so much.
For what it is worth, when Spyderco started the Byrd line, 440C was the specified steel. When the first batch of knives was analyzed, the steel chemistry didn't quite match. It turned out they had used 8Cr13MoV as their equivalent to 440C. I'd say 440A would be close for this 7Cr17MoV.
7cr17mov isnt to bad it has a higher chromium content then 8cr13mov but less carbon so it makes a pretty decent dive knife around 57-59rc
i have a dajo hiker in it, sharpens up pretty well too
Anything from Gerber, not so much... Don't know what they do to their steel or who they get it from, but in the last three years the edges on my Gerbers seem to fall apart faster than I can sharpen them. Their 'mistake' in quoting 7Cr17 as a 440C equivalent and their lack of advertising their steel type is proof that their business model is less than ideal.
I have some Gerbers that are over 25 to 35 years old and they do not list the Steel on them either ~~ but the few of them that I have used ~ hold a pretty good edge.* Bad thing is they are for the most part NIB's and would be doing if I sold them to get what they are selling for at today's prices ~~ so I just keep moving them from Safe to Safe****guess I need to have a sale. lol
- The one from the 90's measured 59.
- The more recent one measured 55.
Either they changed the heat treat schedule or their control of their heat treat ovens sucks little green toads.
To go back to the original question. It's roughly equivalent to 440A.
After digging Chinese steel standards, I can't say the picture is any clearer.
As others pointed out, 7Cr17MoV is equivalent of 440A, not 440C.
However, the interesting part is that, there is no 7Cr17MoV steel neither in GB/T 20878(Stainless and heat resisting steels) nor in GT/T 1220(Stainless steel bars) standard specifications. Only 7Cr17 steel is.
While both standard list up to 0.75% Molybdenum in the 7Cr17 composition, Vanadium is not mentioned at all. There are some sources, listing it with 0.04% Vanadium, but that's very little to seriously affect steel performance. Considering that CPM 154 contains 0.40% Vanadium and maker says it's "residual", I suspect, 10 times less Vanadium is not gonna be anything significant.
There is a trio of 9Cr18xx which matches naming pattern with composition more precisely:
9Cr18 - Doesn't have neither Mo nor V;
9Cr18Mo - 0.40-0.70% Mo;
9Cr18MoV - 1.00-1.30% Mo and 0.07-0.12% V;
If anyone has more precise info on 7Cr17MoV, please let me know.
Actually, the Vanadium content in 7Cr17MoV makes it a closer steel to 440B or 440C than 440A. The carbon content more closely resembles that of 440A, but the added Vanadium apparently increases the heat treating and/or hardness capabilities.
STAINLESS Steels - http://www.agrussell.com/Steel_Guide/a/73/
Carbon (C) Manganese (Mn) Chromium (Cr) Nickel (Ni) Vanadium (V) Molybdenum (Mo) Tungsten (W) Cobalt (Co) Typical Hardness
1.4116 0.45-.050 0.40 14.50-14.80 — 0.10 0.60 — — 55-57
13C26 0.65 0.65 13.00 — — — — — 58-60
14-4CrMo 1.05 0.50 14.00 — — 4.00 — — 60-62
154CM 1.05 0.5 14.0 — — 4.0 — — 58-62
19C27 0.95 0.70 13.50 — — — — — 61-62
20CV 1.90 .30 20.00 — 4.00 1.00 .60 — 60
3Cr13 0.32 1.00 12.00-14.00 — — — — — 54-56
4034 0.42-0.5 1.00 12.50-14.50 — — — — — 54-55
420J2 0.15 1.0 12.00-14.00 — — — — — 49-53
420HC 0.40-0.50 0.8 12.00-14.00 — 0.18 0.6 — — 56-58
425 Modified 0.40-0.54 0.50 13.50-15.00 — 0.10 0.60-1.00 — — 57-59
440XH 1.60 .50 16.00 0.35 0.45 0.80 — — 60-62
440A 0.65-0.75 1.0 16.00-18.00 — — 0.75 — — 55-57
440B 0.75-0.95 1.00 16.00-18.00 — — 0.75 — — 57-59
440C 0.95-1.20 1.0 16.00-18.00 — — 0.75 — — 57-59
7Cr17 0.60-0.75 ≤1.00 16.00-18.00 ≤0.60 — ≤0.75 — — 54-56
8Cr13MoV 0.80 0.40 13.00 0.20 0.10 0.15 — — 58-59
As you can see, the makeup of regular 7Cr17 without the Vanadium is virtually identical to that of the 440A, except for the addition of some nickel in the 7Cr17; and its typical hardness rating of 54-56 is also quite similar to the typical 55-57 hardness rating for 440A. But there are quite a few knives out there now made of 7Cr17MoV with HRC of 58, like the Tekut knives getting issued to some police departments and military. A HRC of 58 would make the 7Cr17MoV more similar to 440B, 440C, or even 8Cr13MoV, which all typically rate 57-59. Since the Vanadium content is the only component differentiating regular 7Cr17 from 7Cr17MoV, I can only conclude it must be responsible for the rather significant increase in hardness properties.
Edit: A little chemical and elemental homework on Vanadium confirms that even a very small amount of Vanadium strengthens steel alloys considerably.
Last edited by G8R8U2; 06-29-2011 at 12:38 AM.
well vanadium does help control the grain structure of the steel during HT so that doesnt surprise me. that being said id still prefer a tougher steel at the HRC then 7cr17 unless they are willing to bump it to 59+/-
Carbon content is more important than Vanadium content when it comes to hardness.
Adding Vanadium to an alloy while maintaining the Carbon content will improve the performance. But adding Vanadium while dropping the Carbon content will make the performance poorer.
I've tried 8Cr14MoV. The performance is considerably less than that of 440C.
This is 7Cr14MoV. You do the math.
0.15% in V increase or even decrease can be easily attributed to production "tolerances"... At any rate, it's simply not enough atoms to account for considerable increase in hardness, and besides, for hardness C, Mo, W, Co are far more important.
It's 7Cr17MoV, and it has 3% more Chromium than the 8Cr14MoV that you've used, which I'm sure you realize also contributes greatly to hardness and edge-holding. In fact, A.G. Russell site I linked suggests that it takes more than 14% Chromium to produce high-carbon stainless steels.
Produces hardness and better edge holding when combined with other alloying materials. Used in fairly large amounts, it produces a blade that resists rust. Takes over 14% to produce high-carbon stainless steels. Expressed as Cr. http://www.agrussell.com/Knife-Encylopedia/a/110/
Seems like some folks believe carbon to be the end-all element in steel, and that formulas with less of it can't make a good or great steel... which is, of course, absurd. H1 steel has .15% carbon (1 tenth that of 440C), and typically has a HRC of 65-68. Sandvik 12C27 has less carbon (about half of what 440C has) than the 7Cr17MoV too, yet readily produces HRC 57-59. Each element alters the properties of the resulting steel, and ignoring their qualities or their quantity in a formula means a less than accurate assumption or opinion about its "grade".
I enjoy the debate, because it forces me to do a lot of homework, and I love research. As is often the case with steel, makeup is only half the story... the treatment seems every bit as important as the content.
In any event, the point was that even with one eighth as much carbon as a 440C blade, an H1 blade with a different makeup, with additional elements in its alloy, and a different treatment, still reached a superior hardness than the 440C blade. The illustration was only meant to show that carbon content is far from the only pertinent characteristic to hardness, toughness, or edge retention.
Even if the Spydercos only attained a rating of 60, which is far below the ratings they've achieved and published, it's still greater than the 57-59 one can expect from a 440C blade with nearly 8 times the carbon content of the H1 blade.
Last edited by G8R8U2; 07-04-2011 at 02:38 AM.
Another example is 420HC. Not generally thought of as that tough a steel, and often viewed as "inferior" with less than half the carbon content of 440C, it can attain the same level of hardness as the 440C if properly heat-treated, as some of the Bucks and Gerbers have proven. Carbon content is not the end-all, be-all of knife blades... far from it.
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