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440 or 1095?

Help,

I see these two listed on allot of knife blade write ups. I see a variety of different materials listed in knife write ups and not sure what is better or what to stay away from.

any help? The 1095 I see on many GEC knives.

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In MemoriamPermalink Reply by D ale on May 1, 2011 at 22:55

??? .. 440 .. what .. ???

imo ..

440A is not cutlery steel .. many manuf disagree with me. It's limited (.6~.75) carbon content also limits it's working hardness to a 51~52 Rc.

440B sees a greater use as cutlery steel .. it is cheap !!! But here again .. it's limited (.75~.95) C content puts it in the 55~56 range.

440 finally gets up to the .95~1.2 range and a working hardness of 57~58 Rc.

Newer tempering process incorporating cryogenic treatments can further improve their performance. Please note I stated working hardness .. the performance area where both tuffness 'n hardness are maximized. They can be hardened to a higher value .. but .. there's more to life than the Rockwell C scale !!!!

1095 .. specs here show it being hardened to a 62 Rc .. others suggest a lower value of 55 .. it's not known for it's corrosion resistance.

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In MemoriamPermalink Reply by D ale on May 1, 2011 at 23:21

???.. 440 .. what ..???

The last link was the 1095 one .. oops .. sincerely sorry !!!

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In MemoriamPermalink Reply by D ale on May 2, 2011 at 0:07

Donald .. there's a steel cross ref chart here you might find handy !!

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Permalink Reply by Bob Miskovic on May 2, 2011 at 4:06

simply put 1095 is carbon steel and 440 series is stainless steel. imo 1095 although common is very good if done properly. this is the same case as mentioned above with 440C. in general stay away from 440A and 440B.

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In MemoriamPermalink Reply by D ale on May 2, 2011 at 8:01

Indeed .. based on what I hear from our peers here @ iKC .. you'll be pleased with GEC's product. AISI 1095 performs admirably when properly tempered.

If a knife is marked stamped "440" or "440 Stainless" or any generic variation where only the "440" is used .. you can downright bet it is NOT 440C. IF 440C is being used .. the manuf will tell you .. 440C isn't cheap. If the "C" isn't included .. all the manuf wants you to see is the "440" .. meaning it is very very likely 440B !!!! ..........or worse.

Please consider the use .. the 440C really might be better in the tackle box .. it's chromium content does help resist the rust. The 1095 will form a patina that gives it some true character .. but I'd restrict it's use to a less humid environment.

imo .. decently tempered .. they'll both cut 'n hold an edge just fine !!!!!

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In MemoriamPermalink Reply by D ale on May 2, 2011 at 8:28

Here's something to think about !!!

If you've ever heard an ole-timer suggest his high carbon skinning knife justs keeps getting better w/ age .... there's something to it .. AISI 1095 "Work Hardens" .. there's a basis in science for the ole boy's statement of its ... " just gettin' better w/ age"

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Permalink Reply by Halicon on May 2, 2011 at 8:45

That's called age hardening my friend.

In any type of martensitic steel leftover austentite, cementite and so on will with time turn into martensite as the steel "ages", a refined form of oxidation which is the basis of the chemical reaction in the steel, basically you let the elements do the job for you.

Work hardening is repeatedly cold steel struck over and over again, or used for so long that this process occurs forcefully as in old anvils reaching crazy HRC values.

Hence why I prefer to work with old woodworking tools or oil in the cutting surface and then let the fresh steel age for half a year or so before I use them.

There's a clear distinction between the two in that the age hardening comes through father time and the second is when you actually use the steel and force the chemical reaction to occur.

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In MemoriamPermalink Reply by Robert Burris on May 2, 2011 at 10:48

We should be having this discussion in the Carbon Steel Group. lol

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In MemoriamPermalink Reply by D ale on May 2, 2011 at 11:12

Hal .. @ the molecular level ......... we're talking about the same thing.

!!! .. it's the viewpoint .. !!!

work-harden

(Engineering / Metallurgy) (tr) to increase the strength or hardness of (a metal) by a mechanical process, such as tension, compression, or torsion.

... by definition .. a mechanical process is involved .. the steel is being actively used !!!

I was trained to consider all forces acting on the steel .. tension .. compression .. torsion .. that occur all the time .. during active use ...and... while just sitting there on the table.

In the steel fab industry .. only compression (hammering . beating ..repeated .. hammering . beating ) were considered. Most only consider compression.

The steel .. if left to it's own devices .. age hardens by the same process .. there exists movement & activity on the molecular level .. they're running into ea other & changes occur to .martensite.austenite. crystals @ the molecular level ....... it just takes longer !!!!

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In MemoriamPermalink Reply by Robert Burris on May 2, 2011 at 11:26

D ale, I can see that work hardening probably works good on a hand knife but probably runs into trouble in machinery knives?

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In MemoriamPermalink Reply by D ale on May 2, 2011 at 12:05

.... hence the further development & improvements to steel. And there is some very specialized steel out there. Some amazing schtuff.

.... and what I personally like .. is that it has driven the cost of D2 low enough that we're seeing it in std production knives. :D

Robert Burris said:

D ale, I can see that work hardening probably works good on a hand knife but probably runs into trouble in machinery knives?

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Permalink Reply by Halicon on May 2, 2011 at 13:06

Dale, I am well aware of that, there's a rather significant difference however.

One can work cold-forge -and- age harden but you can't cold-forge and work harden, if you forge at vital temperatures where the steel crystallizes and creates the desired elements one can produce a greater amount of desired molecules compared to inferior ones that will decline steel performance.

I'm surprised that since you're bringing up the dictionary for the word, you aren't mentioning all elements that are produced in the reaction, forgot your training eh? ;)

So like you say Dale, let's have some fun!

At 700 degrees celsius, ferrite, cementite and pearlite is formed, depending on your chosen carbon percentage the amount differs, less than 0.8% and you get mostly ferrite and pearlite and above you get cementite and pearlite.

Raise the temperature to 727 degrees and you get ferrite and austenite below 0.8% carbon (a normal Jap sword has 0.7% carbon) and above austenite and cementite.

Go above 750 degrees (the most optimal temperature depends on purity but it's roughly at 720-730 degrees with a few exceptions) and you basically only get austenite, now here comes the tricky part; depending on how fast you cool the steel, slowly and austenite reverts to ferrite and pearlite. Cooled rapidly (this is Jap traditional forging, cold forging) you instead get martensite.

Only martensite will make the steel brittle though which is why we don't want to fire the steel too hot but if we combine this method with age-hardening you can achieve a higer percentage of martensite in the steel while keeping the equally important elements of ferrite and pearlite which are vital to a steels life.

So what I'm getting at is that a combination of cold forging and age hardening is superior to just work hardening a blade that has been tempered equally throughout (western blade).

Since you protect the cutting surface you can safely form the martensite from leftover cementite without affecting the ferrite and pearlite (pearlite is a layered mix of ferrite and cementite) which keeps it from being too brittle, something that is impossible with work-hardening which requires what you say, compression. Compression will have an effect on all these elements as well as posing a direct risk of breaking the craft entirely.

The difference hence is that you have a greater control of the molecular activity when age hardening compared to work hardening which requires compression (also becomes rather problematic on finished crafts).

A western steel will thus never reach the same balance of the crystallized structure compared to one forged with cold forging since the cold forging process is many, many times more accurate but in turn also requires that much more from the smith (go more than 2-3 degrees celsius off and you produce something else entirely).