Just Another O1 Field Testing Observation -

R

rlinger

Joined
Mar 29, 2002
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4,591
Being a fan of O1, and many others, I did a little Thanksgiving field test on a O1 blade that is in its finishing stages. I can take a pic or two if requested. Before doing the annual turkey carving chores that only the head of house hold by tradition is qualified to perform - or most often is pressed into doing I washed the blade. Upon drying it was so-so as to what I would expect O1 to look like after being touched by water. Upon completion of carving and then immediately washing and drying it was full of those tarnish blues and other hues we are so fondly accustomed to seeing O1 blades look like. Why is that? To describe a little better: After before hand cleaning with detergent and rinse water and then drying with a towel the blade did have some dark hues however after the actual carving and cleaning and immediate drying the blade was emmensly tarnished with various hues. Why is that?

RL
 
The "colors" are essentially a result of surface oxidation of the steel. In the case of cutting the turkey the colors are "amplified" by the metals reaction with the acids/chemicals in the meat and or whatever other food it comes in contact with (heat can also be a contributor). When just washing it in water/soap there are enough chemicals to react with the blade which caused the initial coloring.

Oxidation is not necessarily bad - in fact metal oxidation processes (bluing and browning are just two commonly used on steel) are extensively used for protection of steel against corrosion. On the other hand oxidation when allowed to go to too far results in the corrosion of the steel - i.e. rust -and if left uncared for it will eventually destroy it.

In comparison "Stainless" steel, which contains significant amounts of chromium, resists corrosion because when exposed to the atmosphere the surface oxidizes slightly and a thin film of chromium oxide forms, preventing any further oxidation. But stainless steel can corrode via a process known as crevice corrosion, also known as oxygen starvation. When exposed to water, salt or fresh, without the presence of air, the "protective chromium oxide" film will not form and the metal will corrode. If the water in question is salt water, the process is accelerated.

Bottomline: If not cared for properly steel rusts. Stainless steel just rusts more slowly....
 
Chuck,

Thank you for that. I can always depend on you for a researched and concise explanation. It still does not forgive O1 for being apparently more notorious for this than other favored simple high carbons seem to be. The fact that you mentioned amount of heat as being a variable was well taken too. I remember Dad cubing cold deer with a O1 blade and though the blade turned as badly it took longer for it to.

RL
 
It's a give and take Rodger. Remember that if 5160 is the king of steel for it's forgiving nature, 01 is certainly the reigning monarch because of it's cutting ability.
Besides, a little oxidation gives it character. Can't make fishing lures out of it but it does have character! :D
 
As stated, it appears that O1 is the "benchmark" when talking about cutting ability. Everything seems to be compared to it.

We always hear, "It cuts about like O1" or "Its not as good as O1"

~or~

"It cuts better than O1!"

(The latter is seldom heard by the way)

Craig
 
Thanks Don. I am not complaining. Its just a matter of curiousity to me and, primarily, I just wanted to share this particular observation of this particular blade. Not forgetting of course that I did ask the question 'WHY'. That Chuck is a real source of good info. I love reading his stuff.

So 5160 is the king of steels uh.

RL
 
CL,

Good point there and well taken even though I am not old enough, experience wise, to relate to those sayings. I do see the point you express though. Is it me (again) or did we stray off the O1 tarnish deal? I even went back to Chuck's post and re-read it just to be sure. Now I may well still have missed it and he no doubt educated me more but I still can't see anything particular to O1 relative to tarnishing. I'm probably misusing that word - tarnish. Whatever it is that O1 loves; that's what I mean (tarnish, oxydation, oxydization).
 
OK then,

We always hear, "It discolors about like O1" or "Its not as bad as O1"

~or~

"It discolors worse than O1"!

:D :D :D

Craig
 
CL,

You nailed it that time.

I keep thinking the answer is rooted in what Chuck was explaining. From all that, not knowing enough yet, I did not come to an answer why the reason O1 is or appears to be particularly keen to tarnishing. Once again though I wonder if the answer is rooted in what Chuck explained. I think of other steels I have some experience with that are similar to O1 in type of steel. What types are they and what chemical composition, I ask. Well D2 is air hardening and is of plenty different analysis to not be relative. 5160 is spring steel. So are the 10XX steels of shallow hardening. What is an oil hardening tool steel of simple high carbon analysis we like to use besides O1, I ask myself. Maybe that is the answer if combined with what Chuck was saying and then comparing O1 to another steel most closely related in type and composition that we like using for our purposes. So, to be fair to O1 what is another oil quenching tool steel of simple high carbon analysys we like to use? Would L6 be one? It has to be a tool steel, medium hardening, simple composition. Off hand I think of none we generally prefer for knife making. If possibly correct then O1 is unique not only for its love of tarnish but also its special place in type of favored knife steel. I can not be correct on that though. There has got to be another medium hardening tool steel of simple analysis we like using other than O1.

RL
 
RL,
I recall reading that tungsten makes steel a bit more prone to
oxidize ( decarb ), and wonder if it has similar effect, though lessend,
at room tamp.
Few non-high speed steels, other than O1, have tungsten in them.

Russ
 
Roger - again basically it's all in the alloy. (and thanks for your confidence - I try and check all my facts but I do make mistakes so it's always best to double check them "just in case" ;) - my Dad was a master machinist/tool and die maker and he taught me early on even the "experts' didn't have all the facts - good advice IMO)

Look up each of the various steels to see what they're make up is: for instance 5160 - Peter's "the King of steel" (I kind of like KC's Duke of steel nom de plume myself - just has a ring to it) has a fairly high chrome content which for it's main intended use, car springs, helps prevent corrosion. (BTW-the term spring steel is really more of a salesman's term IMO than a scientific one - although in the case of 5160 IIRC it was specifically developed as a "spring" steel. But for years when making muzzleloading gunlocks I used 1065-1084 for making all my flat springs and the 10xx series has never been specifically marketed as a "spring" steel - again IIRC - it's been a looooong week!).
Here are some Nominal Chemical analysese(sp?) of various "knife" steels mentioned for comparison:

1084 AISI
Carbon 0.80 to 0.93
Manganese 0.60 to 0.90
Phosphorus 0.040 Max
Sulfur 0.050 Max

5160RH AISI
Carbon 0.56 to 0.64
Manganese 0.75 to 1.00
Silicon 0.15 to 0.35
Chromium 0.70 to 0.90

AISI O1
Carbon .95
Chromium .50
Manganese 1.20
Silicon .35
Tungsten .50

AISI D2
Carbon 1.50
Manganese .40
Silicon .30
Chromium 12.00
Molybdenum .80
Vanadium .90

A note: Wrought Iron. although less "strong" (a relative term best used for comparison) than steel, was long used in structural building because of it's corrosion resistance due to it's high silicate content. Again IIRC carbon content has an effect on the rate/speed of oxidation, but as seen in D2, the chromium content can offset the rate and make it a stainless steel "light".
 
With the list of steels, seeing the make up of them, here's a question off the main topic. What causes one steel to hold an edge longer then another steel? Let's say O1 and 5160. If they are heat treated to the same hardness would the higher amount of carbon in O1 make it better at edge holding? What ingredient makes a knife stay sharper longer?
Scott
 
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