What's up with this file's steel?

E

EatingSarma

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Jun 22, 2020
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Friend of mine has got an idea to make himself knife out of a file.
I also have an old file and I've been thinking about doing the same. So I remembered I have a friend who has spectrometre on her university. And I became curious about the steel used in that file.

I have to take her out for a lunch or dinner, but here's the composition:

Cr - 1.7%
C - 1.4%
W - 1.1%
Mo - 0.9%
Si - 0.6%
V - 0.5%
Mn - 0.4%
Ni - 0.4%
Cu - 0.1%
P - 0.1%

This up there looks like one hot mess and high carbon content makes me worried.
I'm curious to know if this could be a decent knife steel?
And how to bring this thing's hardness down once I shape it into a knife?
Or, should I temper it down before I start working on it?
 
Are you just planning on stock removal? Grind away!

You should be heating it in a forge pounding it into a knife shape then re hardening it.
 
eveled said:
Are you just planning on stock removal? Grind away!

You should be heating it in a forge pounding it into a knife shape then re hardening it.
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I don't have a forge unfortunatley.
My plan was to grind it into a knife shape while constantly spraying it with water and dunking it few times too, and then put it in my home oven for 2 cycles on 200°C, each cycle would be 1hr long.

But this thing looks to be different than plain carbon steel, and I have no idea what temperature should be used to bring this thing's hardness down, or how hard it currently is.
 
Well that steel looks kinda wild...
I did my best and spent some time looking into Zknives charts looking at various tool steels and I'm not finding anything that would match this.

It's basically as if they had lots of various stuff but not a lot of anything so they just decided to blend it all in.

It has slightly higher carbon content than A2, slightly lower carbon content than D2, more vanadium than A2 but less than D2. It also has significant ammount of tungsten but almost no chrome.

All stuff combined, it has way less added stuff than A2 so I would say that it's not wrong to treat it in similar way to plain carbon steels. It should however hold an edge better because of that V and W and carbon content itself.

My guess:
Better edge holding than 1095CV and A2, but less corrosion resistance.
Also, better toughness than D2 but way less corrosion resistance and I would assume less edge retention. I don't know for sure.

If I am wrong, someone please correct me, I just read some stuff and based on that I'm guessing here...
 
danbot said:
Just do it and see what happens! :thumbsup:
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I agree. My guess is that if I make small fixed blade it'll be OK.
abcdef said:
Yeah, just do it. And get her more than soup.
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Don't worry, I'll take her either to some fast food or to some Asian place, I'll let her choose.
Smiling said:
My guess:
Better edge holding than 1095CV and A2, but less corrosion resistance.
Also, better toughness than D2 but way less corrosion resistance and I would assume less edge retention. I don't know for sure.
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I guess, I mean this is a file, so I guess they just crammed in everything they had just to make it hard and wear resistant. Stain resistance was far from priorities here.
 
And now I have to add “mass spectrometer” to the list of tools I want to play with. I haven’t even found someone who will let me use their electron microscope, I wonder if there is a Mad Scientist lab somewhere I could rent.
 
BitingSarcasm said:
And now I have to add “mass spectrometer” to the list of tools I want to play with. I haven’t even found someone who will let me use their electron microscope, I wonder if there is a Mad Scientist lab somewhere I could rent.
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Maybe some universities have it like this one here?

I remembered her telling sories about checking purity of silver, and so on... so I asked her if it would work on steel and if she would test something for me?
She asked me where am I taking her if she does... I said "somewhere to eat" and we got a deal.
And I'm also obligated to show her the knife once I'm done, and she gave me tons of talk how she never thought she'd be carrying rusty old file to the university one day...

One more thing: Clean the rust and/or patina off of at least one part of it before testing.
 
I kind of wondered about possible filings stuck on the file that may have contaminated the results, but your acknowledgement of it in the previous post suggested that wasn't an issue.

There are people on these forums obsess over tiny little insignificant things, and they make it seem like anything less than the top 1% of choices is completely unusable and will be completely blunt if it touches a marshmallow. Don't worry about it, even if the steel was not designed for it, old files are known to make good home made knives. Most files aren't terribly large, so if you are not making a bigger knife that will be subjected to impact I would advise not even tempering it. You can put it in an oven later if you decide it's too hard.

I made a very basic one-piece scalpel sized knife from a small file, and it held an edge rather well without being chippy at the edge. I threw it at a big log many, many, many times and it did not break. I ultimately scrapped it due to rust issues, but if I had provided a minimal amount of oil and care it would have been fine. I took the grooves off completely and made it completely smooth sided. Took a while to grind and keep cool though, you have to go slow and dip it constantly. If the surface turns gold you're grinding too fast, dip it until cold and slow down. if it turns brown or blue the temper is gone and it'll need to be heated and quenched.

It'll work fine, just have fun with it.
 
A good place to start your inquiry would be Charlie Davis’s Anza Knives site. He has been making knives out of files for at least forty years. There is some very general info about his process for treating files to be turned into knives.

If I remember correctly, he starts by annealing the file to make it soft enough to work. He grinds to shape and then tempers the blade to get a usable hardness. I have not seen any detail about what temps he uses or what hardness he shoots for, but you could try asking him.
 
The good thing is, you know what's in it, most people don't have a clue what their old files or saw blades are made of;

That said, I'm not sure what it is, or where it was made, but it Looks to me like a modified version o7?

Without knowing exactly what it is, I would call it
o7 cro-mo
Has a nice ring to it...

Compared to o7 which has 1 - 2% allowable W,
It looks like o7 @ the 1% mark, but replaced the other 1% with double the Chromium and Triple the Moly added to it, as well as tiny +0.1% additions of Carbon, Vanadium, and Nickle...
(Without getting into molar or atomic%, it's essentially o7 at all the highest allowable specs:
-1% W
-0.15% Cu
-0.6% Mn
+1.75% combined across 5 other elements
As well as 0.07% more phosphorous)...

So all in all, while not an exact science, considering all the ingredients are in there, and it's all "relatively" close in specs., (the main differences being between the varying Tungsten/Chromium/Moly amounts, but even those are relatively small on the grand scale), it's certainly not identical by any stretch however it should react at least somewhat similarly to the heat treat process. So without having an exact chart, considering the similarities, I would go off of the o7's heat treat specs. and see what ya get. Should at least get it pretty close, and considering o7's general properties, the increased Chromium and Moly with the Tungsten, (yet all still in relatively low quanties as a whole), as well as the very minute increases of vanadium, nickel, and carbon, it should be decent carbide formation, hardenability, toughness, as well as resist corrosion and pitting better then standard o7, and as file knives go, it should actually make for a decent one...
 
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MarkN86 said:
I kind of wondered about possible filings stuck on the file that may have contaminated the results, but your acknowledgement of it in the previous post suggested that wasn't an issue.

There are people on these forums obsess over tiny little insignificant things, and they make it seem like anything less than the top 1% of choices is completely unusable and will be completely blunt if it touches a marshmallow.
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I cleared the tang of the file with vinegar, then steel wool, and after that sand paper and even diamond polishing paste.

And I'm even pretty happy with steel composition. Even plain old carbon would do it for me.

strategy9 said:
The good thing is, you know what's in it, most people don't have a clue what their old files or saw blades are made of;

That said, I'm not sure what it is, or where it was made, but it Looks to me like a modified version o7?

Without knowing exactly what it is, I would call it
o7 cro-mo
Has a nice ring to it...

Compared to o7 which has 1 - 2% allowable W,
It looks like o7 @ the 1% mark, but replaced the other 1% with double the Chromium and Triple the Moly added to it, as well as tiny +0.1% additions of Carbon, Vanadium, and Nickle...
(Without getting into molar or atomic%, it's essentially o7 at all the highest allowable specs:
-1% W
-0.15% Cu
-0.6% Mn
+1.75% combined across 5 other elements
As well as 0.07% more phosphorous)...

So all in all, while not an exact science, considering all the ingredients are in there, and it's all "relatively" close in specs., (the main differences being between the varying Tungsten/Chromium/Moly amounts, but even those are relatively small on the grand scale), it's certainly not identical by any stretch however it should react at least somewhat similarly to the heat treat process. So without having an exact chart, considering the similarities, I would go off of the o7's heat treat specs. and see what ya get. Should at least get it pretty close, and considering o7's general properties, the increased Chromium and Moly with the Tungsten, (yet all still in relatively low quanties as a whole), as well as the very minute increases of vanadium, nickel, and carbon, it should be decent carbide formation, hardenability, toughness, as well as resist corrosion and pitting better then standard o7, and as file knives go, it should actually make for a decent one...
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Thank you!
This is the kind of comment I was hoping to get. I didn't even know such thing as O7 exists.
File is already hardened, so I only need to bring it's hardness down a bit once I'm done shaping it (or before).
I wanted to know the temperature that's best to use tho, hence looking into it's composition.
But it is wear resistant for sure, I played a bit with sand paper and other abrasives. Tang seems to be bit softer tho.

Now, this file was made somewhere in former Yugoslavia, meaning it is at least 30 years old. It is possible they tried to make O7, but lacked enough W so they just tossed in what they had instead.

I found some charts on O7 and similar steels here:
https://knifesteelnerds.com/2018/03...uper-the-facts-about-tungsten-alloyed-steels/

Also when I looked at this chart:
http://www.zknives.com/knives/steels/steelgraph.php?nm=o7&ss=1

Here I can see it could be modified O7.
In O7 the W is usually between 1-2%, here it is 1.1% which is on lower end, but Cr, V, Mo and Ni should make up for it. In small quantities those increase toughness, and less Mn is also meaning less it is less brittle.

My wild guess:
They made it in such way to be hard and wear resistant but also decently tough, and they probably used this stuff for more things than just files. This file was probably made out of this because they simply had it, it can be hardened and is wear resistant so why not?
I can imagine they also made dies, shapes and other tools out of this stuff back in the day.
I would say it is a bit less wear resistant than standard O7 but it's also probably tougher.
 
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Indeed, there are just so many steels out there it's crazy... not to mention all the mods, manufacturers tweaking their proprietary versions of the same steels, it is a bit overwhelming.

That said, knowing it came from Yugoslavia, I used Zknives to search steels from that region, (assuming it was local steel, which it very well may not have been, it very well could have been sourced from afar),
But a standard in Slovenia called c.6441.9 exists, ow3 is the proprietary name by Metal Ravine in Slovenia, which compared to AISI o7 standard actually allows for up to 1.3% chromium, and allows for the lower Maganese threshold, CrWMn in China;
Davido in Japan has an identical proprietary called GO31 Crucibles version is called Tungsten Tap & Die, Germany has a standard 110xcrv5 which allows for less sulphur, silicone, and no copper
so again, being a slightly modified version of that steel isn't so unlikely, and substituting Moly for Tungsten to save $ is not completely unheard of...

Considering you say it's at least 30 yrs old, and Yugoslavia fell apart 38 years ago and the entire region was in turmoil for a long time during that period, my best guess would be that it was made between a combination of substituting materials to cut costs, coupled with simply being made hastily and without very tight production tolerances in place, leading to %'s being a tad bit off of their marks...
 
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My take on it is that you should just call it O7Cro-Mo and be happy with it.

Make smaller fixed blades and temper it down on pretty much same temperature to use on plain carbon steels, since this steel doesn't seem to be very high alloy. Even if it stays a bit on the hard side it won't really matter since it's acceptable for a small fixed blade, there won't be any chips since you won't really chop with it and it'll be thick behind the edge, plus at this thickness (6-7mm) I doubt it'll ever break on you. It can be a small sharpened pry bar, exactly the way you like, and I remember you complaining that there's no any small but thick carbon knives to buy.

In reality:
You can make the knife yourself to your liking
It's also made out of steel that's extremley uncommon in knives, I doubt you'll ever meet someone who has a knife in that same steel
This steel seems to be tough and wear resistant too

I don't see anything about this.
I'd personally temper it with that classic 2x 1hr cycle at 200C, even if it stays bit too hard - not a problem if it's a small blade.
 
EatingSarma said:
Friend of mine has got an idea to make himself knife out of a file.
I also have an old file and I've been thinking about doing the same. So I remembered I have a friend who has spectrometre on her university. And I became curious about the steel used in that file.

I have to take her out for a lunch or dinner, but here's the composition:

Cr - 1.7%
C - 1.4%
W - 1.1%
Mo - 0.9%
Si - 0.6%
V - 0.5%
Mn - 0.4%
Ni - 0.4%
Cu - 0.1%
P - 0.1%

This up there looks like one hot mess and high carbon content makes me worried.
I'm curious to know if this could be a decent knife steel?
And how to bring this thing's hardness down once I shape it into a knife?
Or, should I temper it down before I start working on it?
Click to expand...
From the looks of it it will make a more than decent knife, my only worry would be the 0,1% P...
And it will eat a lot of belts ;)
Good luck and have fun!
 
So I asked a bit more about that file and even asked local knife maker (ex Yu area) for tips.

So:
1. This file is even older than I initially thought. It is from the time of former Yugoslavia, I said it's definitley over 30 years old, but it's over 40 actually.
2. Everyone says tools were of much higher quality back then.

Then I went back to the file, and this file actually still has it's bite, especially at the edges and non corroded areas (rust is only on surface).

The knife maker gave me advice to anneal it first since this steel at this hardness will be a chore to grind and if I do something wrong I could still mess up the heat treat.
I also got advice how to quench and temper, but I don't have the forge or any place to heat it to the temperature where I can go into the quench.

So I'll try to do it like the way I originally planned, if I mess it up, then I'm going to anneal it and basically do everything I want to do, and once I'm done - take it to the company that heat treats stuff for you.
It will cost me, true, but they will quench and temper it either to HRC you want or HRC they see as appropriate if you didn't state anything. One thing they will ask you is - "What steel do you have?"
-I think saying it's similar to O7 would be fine, I did more research and either OW3 or c.6441.9 would be fine, they were both called Č6441. They were used a lot, especially for tools that required high hardness and wear resistance.
This steel was even used for dies and punches.

Slovenia and Macedonia mainly produced steels like that, these steels were mass produced and their composition varied a lot. Instead of using various steels like we see today, the guys back in the day would just tweak the composition of the steels they already produce instead and/or heat treat it to another hardness.
Another role was played by politics, as communist propaganda wanted to use their own materials and were against import.
So, in a nutshell, instead of using let's say D2 for dies and A2 for punches, you had two O7 modifications heat treated to different hardness.
With that being said, all consistency goes through window and you have the elements off the charts like we can see here with numbers all over the place.
But as long as it worked for them - it's all good.

At the other hand, when it comes to this file being a file, if it was new it'd actually be a really damn good file.

All tips are welcome tho.
 
Update:

I decided to try and give it a go this weekend. Just to see how it'll look like.

I clamped the file and as the sandpaper disc was already on it - I decided to try to smooth out the surface a little so I can draw on it better.

This steel does not want to be sanded. I was careful to keep it cool and I didn't overheat it but I gave up pretty fast, since I didn't had that much time and I wasn't really getting anywhere
This steel simply does not want to be ground. I will try #40 disc next.

Any ideas what can I use for grinding

Soon I plan to cut out the handle shape and smooth it a little, then grind the blade and finally cut it off the rest of the file once I'm done (it's easier to clamp it while it's long).
 
you're going to have a really hard time with this, as is.... I'm guessing the hardness is up around 63-65

aluminum oxide is a good place to start, if it doesn't work you'll need to get diamonds

honestly you'd be better off just getting a proper 1/8" (3.2mm) piece of bar stock from a knife supplier
I bet since you're in Europe you could get 14c28n sandvik easily without much shipping cost
 
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