What is Cases CV steel?

[Sharpnessis]

I realize it's great, and it sharpens easily, and holds a razor sharp edge for a decent amount of time if you strop it frequently. But what is the actual steel name? How hard is it on a rockwell scale? What is the actual composition? Thanks for help.

C:0.86; V:0.22; Cr:0.65; Mn:0.68; P:0.07; S:0.012; Si:0.24. According to my "knife steel" app!

 

[Frotier76]

Being that this thread is a few years old and you have received an answer on Case's CV Steel sharpening ease and much better edge retention than Tru-Sharp lies in one word...purity.Let's say you took 440A Stainless and 1095 Carbon Steel and gave them the same heat treatment.A Rockwell test is done and the 440A tests at 57rc while the 1095 comes out at 59rc.Keep in mind though every manufacturer uses different time durations in heat treatment so this hardness isn't pointing fingers to anyone in particular.That's because stainless steels are generally soft and through alloying they generally take more work to get equally as hard.1095 is a snap to work with because aside from a high carbon content it's a very bare steel as far as other elements.That purity of carbon steel allows it to bring back a keener edge and in shorter time...even honing a new edge.Putting aside a lot of carbon that harder edge produced can take a lot more when cutting various kinds of materials.Case's CV steel and common carbon steels are very inexpensive as it's just basic tool steel.They aren't rust resistant they're just meant to be tough,hold an edge really well and sharpen up nicely.That gives a firmer perspective when you're using drill bits and try to imagine how often they'd wear down if they were made from 420HC Stainless.

 

[knarfeng]

Seeing as how this has already been resurrected from the dead, I might as well add a couple of items from information gathered since the last time I posted in this thread.

According to an email I received from Case in the time after I last posted in this thread, it is impossible to measure the Rockwell hardness on the tang because all the tangs are softened prior to the ID stamping. A standard Rockwell tester requires a flat area upon which to take a valid reading. On most knives the only flat area is the tang. Since Case softens the tangs, his means that I can't measure the actual hardness of the cutting blade.

However, Case also told me in that email that they harden the CV blades to ~59HRC. I have no reason to doubt them.

So, based on the cert from 1968 and the email from Case in May of 2013
Hardness is 59HRC.
Composition is
C = 0.85
V = 0.22
Cr = 0.63
Si = 0.24
Mn = 0.68

 

[jacktrades_nbk]

Good piece of information, thanks.
I thought the HRC was a bit lower.

 

[Obsessed with Edges]

Regarding the 'purity' of one steel type versus another, if you look & read around a bit on the web, you'll find lengthy discussions by well-regarded knifemakers on the topic. 1095, in particular, is known to vary all over the place in it's purity, and that can lead to some truly horrid results in performance. On paper, it SHOULD seem simpler with minimal alloying elements; but depending on whom manufactured it, there are often a lot of contaminants or inclusions that impact it's performance after heat-treat. This could apply to any non-proprietary steel recipe (such as AISI-spec'd steels like 1095, 420HC, 440A/C, etc), being manufactured widely by many different companies. It cannot be generically assumed that 1095 is always going to be more 'pure', because it's purity (in reality) is dependant on the quality of manufacture. Sometimes it's great in it's finished form, and other times it's absolutely terrible (I have examples of each in 1095 blades, the lesser of which could be put to shame by some decent 420HC blades).

The biggest obstacle to hardness or edge retention, with 420HC, is the lower carbon content at ~0.45-0.6%, which is barely more than half that of CV or 1095 (0.85-1.05% or so). Carbon is what makes steel hardenable by heat treat, and in amounts up to about ~2% or so, the more potential the steel has for greater hardenability. The higher carbon in CV or 1095, as compared to 420HC, is what will give it a built-in advantage in edge holding (assuming heat treat and everything else is competent). Lots of other factors play into it, but the carbon is fundametal to edge-holding, if heat treat or anything else is going to make much of a difference.

Over the years, Case's 420HC 'Tru-Sharp' has shown more variability in edge-taking or retention, as compared to what I've seen in their CV blades. But, I do have some of both in more recent vintage (post-2000), and edge retention between the two is essentially similar at the typically conservative hardness levels they set for them. I find myself touching up either one at essentially the same intervals, and to the same extent after using them in the same everyday tasks (I often carry at least one of each every day).


David

 

[StrayRound]

My father bought me my first Case in 1971 in CV and I've carried both the CV and Tru-Sharp off and on ever since.

I think the two steels are just about identical. The CV might be a tad easier to get scary sharp and the Tru-Sharp might hold an edge a tad longer but I'm not swearing to it.

 

[navihawk]

The thing I like about CV is that you can keep it looking like new with little care. Sure it will rust and patina but CV and D2 are more resistant than 1095 to stains. You still have to care for it, but I like the looks of it.

 

[wazu013]

Here's a link with some answers for you.
http://www.bladeforums.com/forums/showthread.php/396839-Carbon-V-Steel-vs-1095-Steel

 

[Obsessed with Edges]

Here's a link with some answers for you.
http://www.bladeforums.com/forums/showthread.php/396839-Carbon-V-Steel-vs-1095-Steel

Lots of very specific and GOOD info there. Thanks for linking that. :thumbup:

On this thread's general topic (Case CV), I was fiddling with a small SiC (silicon carbide) 3" pocket stone I picked up at ACE Hardware a couple days ago. In checking it out, I put a new edge on the clip blade of my Case 6375 CV stockman, and the steel absolutely LOVES this stone. The finish is likely something like ~320 grit or so; very toothy but hair-popping sharp, with just a little stropping on green compound to clean up any burrs. Might be the best edge I've seen on a CV blade of mine so far. If anyone's wondering what 'works' in sharpening CV, that stone is worth a look. They also carry the same type in 4", 6" and 8" sizes (and I have all of them, including two of the pocket stones ). These stones are the same exact abrasive (so far as I can tell) as the Norton 'Economy' stones found at Home Depot, but packaged and branded in ACE's own name. I suspect they might all be spec'd and/or manufactured by the same company, they're so consistent. The larger stones are all two-sided C/F, while the pocket stone is a single grit, likely equivalent to the 'Fine' on the others.


David

 

[knarfeng]

"Carbon V" is not the same as "CV".

They are similar, but have different compositions.

"Carbon V" had several compositions, depending on who was making the knives for Cold Steel.

 

[cilohaefink]

I read through the other thread and some very interesting info there. However; I am not sure about some of the dates/facts presented. Case's first documented use of CV steel that I can find is from a catalog circa 1933-1934. It is certainly possible that the mention of Sharon Steel developing it in the 1950's was that they perhaps developed a new formulation.

My guess is that Case began using CV steel for pocket knife blades circa 1930 when they opened their new manufacturing facility the Foster Brook Plant (aka the Russell Blvd. Plant). I believe at that time Case switched from the older method of forging pocket knife blades using trip hammers to stamping blades out of sheet steel. The new plant was designed around the new manufacturing process. That would be a logical time to move to a new steel formulation to get a leg up on the competition.View attachment 501752

 

[jacktrades_nbk]

I found out this "trick" with the silicon carbide stone when i worked to set a new bevel on my yellow peanut. It's a small stone, has about 300-400 grit. as you say David, and it put a very nice toothy edge on the CV steel.
Don't know how similar this little stone is to yours, but the result seems the same to me.

 

[cilohaefink]

Case CV steel order from 1957 from Crucible Steel Corp.

 

[cilohaefink]

Case CV steel order from 1968 from Crucible Steel Corp.

 

[knarfeng]

Yes. I have those. Note that they are not the same composition.