HT and hardness of Survive! Cru Forge V? Toughness relative to other steels?

timichango

timichango

Joined
Apr 26, 2013
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771
Hey all!

Having just ordered a factory second CFV 4.7, I've been doing some reading about CFV, and I'm curious if there's any information around about the hardness that the GSO blades are heat-treated and tempered to, and/or anything about the kind of heat treat being used? Or is the latter info proprietary?

From the admittedly limited reading I've done, CFV seems to get compared to 52100 a bunch (ie. more or less the same stuff as Busse SR-101), but with some added vanadium. Due to vanadium and very high carbon, it's supposed to have pretty insane wear resistance with a good heat treat. What I'm mostly wondering about is what kind of toughness we can expect from the CFV GSOs, relative to 3V, and the other materials — and compared to other knife steels in general.

I can't seem to find many direct comparisons between CFV and other contemporary 'heavy use' steels, so I'm curious to know generally what to expect from CFV — aside from wear resistance —*and consequently how to treat mine when it gets here... including how folks are finding sharpening it when it does eventually dull, given all those carbides.
 
I would assume that the hardness would be in the range of Guy's other knives, 59.5-60.5, but that's just a guess.
 
timichango said:
Hey all!

Having just ordered a factory second CFV 4.7, I've been doing some reading about CFV, and I'm curious if there's any information around about the hardness that the GSO blades are heat-treated and tempered to, and/or anything about the kind of heat treat being used? Or is the latter info proprietary?

From the admittedly limited reading I've done, CFV seems to get compared to 52100 a bunch (ie. more or less the same stuff as Busse SR-101), but with some added vanadium. Due to vanadium and very high carbon, it's supposed to have pretty insane wear resistance with a good heat treat. What I'm mostly wondering about is what kind of toughness we can expect from the CFV GSOs, relative to 3V, and the other materials — and compared to other knife steels in general.

I can't seem to find many direct comparisons between CFV and other contemporary 'heavy use' steels, so I'm curious to know generally what to expect from CFV — aside from wear resistance —*and consequently how to treat mine when it gets here... including how folks are finding sharpening it when it does eventually dull, given all those carbides.
Click to expand...

Guy mentioned on Instagram when they revealed the choice:
The steel data sheet is pretty easy to find. We should have one listed on our site soon. The hardness is 59-60HRC on these.
Click to expand...

He also said this, regarding S7 steel that was previously used in the SK-4s and was a suspect for the "mystery" carbon steel:
I doubt that I'll be using much S7 steel in the future. We only used it once in the past. It works well, just not quite what I was looking for in a regularly carried steel.
Click to expand...

Cruforge V was developed to be very similar to 52100 but easier to forge (hence the name) and trades in chromium for vanadium to aid abrasion resistance. However, that's only 0.75% vanadium by weight, it should still be very easy to sharpen on basic hones, the carbide content is quite low (<5%). This is NOT in the league of high-carbide steel like S30V (14.5%) and 154CM (17.5%). Wear resistance will be better than 52100 (when properly HT'd) but not as good as those others, including CPM-3V which also has <5% carbide but has 2.75% vanadium to bolster edge-retention.

Regarding toughness, Cruforge V sports similar toughness to 52100 which will be in the range of 40-50 J Charpy C-notch. That compares to 90-100 J for CPM-3V and 25-30J for S30V/S35VN etc. How does that translate to real-world use? Well, I tested my CfV blade against a new S!K 5.1 in the same tasks, including pounding through thin sheet metal (steel gutter/roofing) - the 3V blade took NO perceivable damage, while the CfV blade rolled/flattened/tore at the apex. Each features the same hardness, one can surmise that the tougher CPM-3V was more resilient to the stresses and so required less maintenance afterward. I will also note that CPM-3V is more corrosion-resistant, particularly with the new HT methods utilized by Survive! as developed by Nathan Carothers and Dan Keffeler with Peter's HT, dubbing it Delta-3V (though the 3V blade shown below was NOT delta). In my tests, the CruforgeV actually performed much better than Becker 1095CV and Busse SR101, but not as well as CPM-3V or INFI. Perhaps in my next comparisons, I will include some 420HC and another stainless...

[video=youtube;SMmiBGMXU6o]https://www.youtube.com/watch?v=SMmiBGMXU6o[/video]
[video=youtube;TbHKydzeHJo]https://www.youtube.com/watch?v=TbHKydzeHJo[/video]
[video=youtube;gYWafo6EoTM]https://www.youtube.com/watch?v=gYWafo6EoTM[/video]
 
chiral.grolim said:
Guy mentioned on Instagram when they revealed the choice:


He also said this, regarding S7 steel that was previously used in the SK-4s and was a suspect for the "mystery" carbon steel:


Cruforge V was developed to be very similar to 52100 but easier to forge (hence the name) and trades in chromium for vanadium to aid abrasion resistance. However, that's only 0.75% vanadium by weight, it should still be very easy to sharpen on basic hones, the carbide content is quite low (<5%). This is NOT in the league of high-carbide steel like S30V (14.5%) and 154CM (17.5%). Wear resistance will be better than 52100 (when properly HT'd) but not as good as those others, including CPM-3V which also has <5% carbide but has 2.75% vanadium to bolster edge-retention.

Regarding toughness, Cruforge V sports similar toughness to 52100 which will be in the range of 40-50 J Charpy C-notch. That compares to 90-100 J for CPM-3V and 25-30J for S30V/S35VN etc. How does that translate to real-world use? Well, I tested my CfV blade against a new S!K 5.1 in the same tasks, including pounding through thin sheet metal (steel gutter/roofing) - the 3V blade took NO perceivable damage, while the CfV blade rolled/flattened/tore at the apex. Each features the same hardness, one can surmise that the tougher CPM-3V was more resilient to the stresses and so required less maintenance afterward. I will also note that CPM-3V is more corrosion-resistant, particularly with the new HT methods utilized by Survive! as developed by Nathan Carothers and Dan Keffeler with Peter's HT, dubbing it Delta-3V (though the 3V blade shown below was NOT delta). In my tests, the CruforgeV actually performed much better than Becker 1095CV and Busse SR101, but not as well as CPM-3V or INFI. Perhaps in my next comparisons, I will include some 420HC and another stainless...

[video=youtube;SMmiBGMXU6o]https://www.youtube.com/watch?v=SMmiBGMXU6o[/video]
[video=youtube;TbHKydzeHJo]https://www.youtube.com/watch?v=TbHKydzeHJo[/video]
[video=youtube;gYWafo6EoTM]https://www.youtube.com/watch?v=gYWafo6EoTM[/video]
Click to expand...

Chiral in your experience how does the gerber strongarm compare ?
I have used it hard and it held up extremely well. I am pretty impressed with 420hc
420hc makes me rething my steelsnob views
 
Isnt it funny when some "crappy steel" surprises the heck out of you??? I have a strongarm too. Its a pretty amazing knife for its price.
 
Riz! said:
Isnt it funny when some "crappy steel" surprises the heck out of you??? I have a strongarm too. Its a pretty amazing knife for its price.
Click to expand...

I've never been able to get into Gerber stuff at all — their design aesthetics always seems ostentatious and unnecessary (kinda like Oakley stuff), and the Gerber knives/multitools I've had have been pretty clumsy and underwhelming. That said, for the price, if I can find one on sale, it might be a good 'throw it in the glovebox' knife. Then again, so might be a Becker BK15/BK16, for the same or less money.

Cool to know, in general, though, that 420HC isn't junk.
 
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Is this 420HC you guys are bantering about the same formula as what Buck has been using for over 30 years? Did Gerber find something new to do with it? Because, while it wasn't crap by any means, the Buck 420HC was, IMO, quite underwhelming.
 
dogboye said:
Is this 420HC you guys are bantering about the same formula as what Buck has been using for over 30 years? Did Gerber find something new to do with it? Because, while it wasn't crap by any means, the Buck 420HC was, IMO, quite underwhelming.
Click to expand...
I don't know about what Gerber is doing with 420HC, but the Buck HT on 420HC improves the industry?/datasheet hardness by 2pts (58 vs 56) if I remember correctly and was formulated by Paul Boss. I would say that Buck's 420HC is a good steel, and probably better than the typical 420HC that's out there, but I too have never been excited about it, so if theirs is on the higher end of the 420HC out there, I don't think of it (420HC) in general that highly. Again, I don't know what Gerber has.
 
I can test the Gerber 420HC too... I did a run through the sheet metal with my Buck 140 Paklite skinner... but I may have thinned the edge a bit too much, need to re-test after I restore the apex and a definite angle. It took some serious damage.

By the way, a curiousity from the sheet-metal cutting: so the INFI and S!K 3V tested passed with flying colors, other steels took damage, but certain knives seem to collect scrapings of steel off the sheet-metal as they go through... Theories on why this might be? The 2.7 pass-around got tested (just needs to be restored, then I'll be sending it along, sorry for the delay) and had this issue, as did the Buck, as did the RMD i tested before, but it didn't happen to the Izula or BK16 of CfV 4.7 or GSO-5.1...

And by the way, DON'T replace your tin-snips with a GSO-2.7 for cutting sheet metal :o The edge geometry is the same as the 3V 5.1 and CfV 4.7, but this 20CV did NOT like to be used this way.
 
chiral.grolim said:
by the way, DON'T replace your tin-snips with a GSO-2.7 for cutting sheet metal :o The edge geometry is the same as the 3V 5.1 and CfV 4.7, but this 20CV did NOT like to be used this way.
Click to expand...

Good to know. Especially since the 20CV 5.1 is all I have. For now. My CruV is supposed to be delivered tomorrow. &#128556;&#128526;
 
Chiral, what you are describing sounds like galling (metal surfaces sticking together instead of sliding past each other).
It relates to alloy composition, hardness and surface finish and is one of the factors in designing threaded parts.
I can't see a pattern between the different knives you mention but it could be something like sulfur content that we don't have data for.
 
Fancier said:
Chiral, what you are describing sounds like galling (metal surfaces sticking together instead of sliding past each other).
It relates to alloy composition, hardness and surface finish and is one of the factors in designing threaded parts.
I can't see a pattern between the different knives you mention but it could be something like sulfur content that we don't have data for.
Click to expand...

HA! It's ME, I AM the pattern! Each of the knives presenting the "galling" (thank you very much for that) required more thorough bevel-work than those that did not gall. It must be something I am doing (or not doing)... I'll work on this, thank you again, Fancier.
 
Fancier said:
Chiral, what you are describing sounds like galling (metal surfaces sticking together instead of sliding past each other).
It relates to alloy composition, hardness and surface finish and is one of the factors in designing threaded parts.
I can't see a pattern between the different knives you mention but it could be something like sulfur content that we don't have data for.
Click to expand...

I'd say almost 100% in this case from edge finish. The addition of cobalt prevents galling and helps with hot hardness, but is usually realized when used in applications such as steam valve seats, etc.
 
I have heard people refer to Cru Forge as "52100 Lite" but it kind of started off as something more like W2 with a LOT more vanadium, like 4-5 times as much, and a manganese content more like 1084. From what I was told, the .5% chromium was added to the final version to make it easier to roll and even more deep hardening. It has a chrome content like 5160 or 50-100B. It does not have the pinch of moly and nickel like the 50-100B/0170-6/1095 CroVan. As best as I can tell, it was never intended for the chromium to be the major carbide former like in 52100. Limited feedback seems to indicate that the only downside of that moderate amount of chromium is that it causes the steel to etch a bit "gray" when when used in damascus as opposed to the more "black" look you would normally get with .75% manganese.
 
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