Looking for some steel advice

S

skiracer218

Joined
Jul 27, 2014
Messages
11
I've decided I want to go big for my next knife. I'm thinking in the range of 10-11" blade, a little over 2" wide, probably .25 thick at the spine. The steel needs to have a high degree of toughness as it's going to be used, and used hard. 3V was my first choice, but I cant seem to find any with the dimensions I'm looking for (for a reasonable price). I've also looked at A2, O1, and S7. The more I get into it the better S7 sounds, but I know very little about it as a knife steel. I know it's really tough, but how rust resistant is it, and more importantly, how is the edge retention? How easy is it to work with? How hard should it be? Stuff about A2 was pretty easy to find, but I'm still looking for a direct comparison between 3V, O1, and A2, especially in edge retention. All these steels seem like great candidates, but there seem to be very few knives out there made in them. Is there any good reason?

In a more general sense, is there anything extra tricky about working with a piece of steel this big? This knife will probably be almost 16" long, almost double anything I've done in the past. Also, if anyone has a really high toughness steel that works well for them, feel free to recommend, I'm really new at this and if there's something I'm missing I'd love to hear about it.

Thanks,
Jon
 
So pretty much any of the steels you mentioned should be fine for a chopper like you're planning on making. 1095, 1084, 5160 and so on would work well too.

S7 is the toughest of the medium alloy steels, by at least 3-4x according to the datasheets from crucible. 3V is next, then A2, then O1. Part of this also depends on how high you want to take the hardness, I know there are several makers of practical swords that recommend hardening 3V to 61HRC and don't have issues.

From reading through the datasheet for S7, my take is that it will likely hold an edge in a similar fashion to other lower carbon alloy steels like AEB-L. It will likely hold a fine keen edge for a reasonable amount of time, but because it doesn't have enough carbon to form many carbides it likely won't do so well in terms of holding an edge when cutting abrasive materials like cardboard. At a guess I'd say edge stability should be pretty decent at high hardnesses, but I'd love to hear more from people who've actually used the steel. Please note that all of the above constitutes a WAG (wild-ass guess) from reading the datasheets, and before you spend the money on the steel you should definitely track down someone that uses it and have a good chat with them.

I don't know of many people who use S7 in their knives (only one comes to mind actually), I'd certainly love to hear more about it!
 
Last edited:
A .250X2X36" bar of CPM-D-2 will run about $106. CPM-3V will run about $110. Both will be really tough. The D-2 will be more corrosion resistant. Go with CPM steel for such a big knife.
 
I know Daniel Fairly has used used S7 "at least" a few times, probably quite a bit actually. I wonder what he thinks about it, you could pm him or etc. He has his own sub-forum in the hosted knifemakers forums section in case ya don't know who he is :)

-Paul
My Channel Lsubslimed
 
Frank Niro said:
Just a note, AREB-L is not a low carbon steel. Frank
Click to expand...

Right you are! I should have said 'relatively low carbon' or perhaps 'hypoeutectoid', I know it only has 0.67% carbon specifically so that it doesn't form carbides, which was the main thing I was driving at with my comment as S7 is also a hypoeutectoid steel, which is something that's relatively rare in a cutlery steel (as far as I know!). I will fix the wording!
 
3V keeps sounding better and better, but I cant seem to find a good source for something that thick, it seems to be sold out everywhere...any advice on where to pick it up? Anyway, Ive heard that 3V is more corrosion resistant than D2, and many times more tough, is that actually not the case?
 
skiracer218 said:
3V keeps sounding better and better, but I cant seem to find a good source for something that thick, it seems to be sold out everywhere...any advice on where to pick it up? Anyway, Ive heard that 3V is more corrosion resistant than D2, and many times more tough, is that actually not the case?
Click to expand...

3V is really good stuff! You can get it direct from the mill, but it won't be cheap as they price so as to not undercut their distributors: http://nsm-ny.com/

I'll let people who've used both 3V and CPM-D2 answer your questions about them, I've only used 3V.
 
bladsmth said:
A .250X2X36" bar of CPM-D-2 will run about $106. CPM-3V will run about $110. Both will be really tough. The D-2 will be more corrosion resistant.
Click to expand...

I disagree. It may look that way on paper due to chromium content, but in practice, I've found CPM-3V to be noticeably better than D2 and CPM-D2 as regards corrosion-resistance. All three are frankly pretty good; they will bloom and pit a little if neglected, but not nearly as much as simpler steels. In really neglectful "testing" in my shop*, D2 eventually turns into a horrible flaky mess; CPM-D2 is clearly more resistant than the "regular" version; CPM-3V takes a helluva lot longer to reach that state.

3V is much tougher than D2, with pretty much the same wear-resistance and edge-holding at the same hardness/geometry... that's why it was developed in the first place. CPM-D2 in my opinion is a half-measure that never lived up to the hype. I've said it before and I'll say it again... if you like D2, you're gonna love 3V and never look back.

* fully-hardened and finished blades purposely left to languish without any coating or oil in the same conditions over a period of years, not weeks or months (several humid summers in Central WI and East TN)... D2/CPM-D2 rusts more readily and more deeply than 3V.
 
That's more like what I've heard about D2 vs 3V. I have a source for S7 that's so cheap it's going to be hard to pass up...but I'm still looking for more info about how it performs practically as a blade steel. I know lots of guys really like A2 as well, I know it's fairly tough and wear resistant, but how does it do against rust?
 
skiracer218 said:
That's more like what I've heard about D2 vs 3V. I have a source for S7 that's so cheap it's going to be hard to pass up...but I'm still looking for more info about how it performs practically as a blade steel. I know lots of guys really like A2 as well, I know it's fairly tough and wear resistant, but how does it do against rust?
Click to expand...

Gavko has used S7 in his chopping blades for some time with no issues.

[video=youtube;5EswohLOh3w]https://www.youtube.com/watch?v=5EswohLOh3w[/video]

Straight from Crucible:

http://www.crucibleservice.com/eselector/general/generalpart1.html

For better impact toughness than D2 tools (20 ft-lbs)

• GOOD
&n— A2 - 45 ft-lbs
• BETTER
&n— CPM 3V - 55/80 ft-lbs
&n— CPM 9V (if lower hardness OK) - 50/70 ft-lbs
• BEST
&n— A9 (coated or nitrided for wear) - 80/100 ft-lbs
&n— S7 ( low wear resistance) - 100/125 ft-lbs

In short. It works great as a blade steel.
 
Jantz may have some CPM 3-V in stock.
 
I wish you wouldn't take impact strength data as an absolute .Approximate yes , absolute no !! In my experiance as a metallurgist it doesn't always work as the tables suggest ! CPM will be tougher than standard grades especially in the tranverse mode. Design , HT are big infuences. How many knives have you seen with sharp corners at the blade -tang intersection ? And how many breaks ? Sharp corners = bad design ! You'd be surprized at how many engineers dont know that !!
 
skiracer218 said:
I've decided I want to go big for my next knife. I'm thinking in the range of 10-11" blade, a little over 2" wide, probably .25 thick at the spine. The steel needs to have a high degree of toughness as it's going to be used, and used hard. 3V was my first choice, but I cant seem to find any with the dimensions I'm looking for (for a reasonable price). I've also looked at A2, O1, and S7. The more I get into it the better S7 sounds, but I know very little about it as a knife steel. I know it's really tough, but how rust resistant is it, and more importantly, how is the edge retention? How easy is it to work with? How hard should it be? Stuff about A2 was pretty easy to find, but I'm still looking for a direct comparison between 3V, O1, and A2, especially in edge retention. All these steels seem like great candidates, but there seem to be very few knives out there made in them. Is there any good reason?

In a more general sense, is there anything extra tricky about working with a piece of steel this big? This knife will probably be almost 16" long, almost double anything I've done in the past. Also, if anyone has a really high toughness steel that works well for them, feel free to recommend, I'm really new at this and if there's something I'm missing I'd love to hear about it.

Thanks,
Jon
Click to expand...

For your first big knife, why not start with something tough and simple like 5160? I garuntee you won't easily break 1/4" of it. You might need to modify your work rest for working with a large piece, but otherwise its business as usual
 
I'd go with S7 or 5160, either way you really can't go wrong. 5160 costs less but has scale to deal with... S7 comes a bit cleaner and precision ground. 5160 can hit a high RC and still be strong, it's something you don't see done a lot but my testing has shown it to be quite impressive.

just for fun...
 
You must log in or register to reply here.
Back
Top