Grain direction on O-1 and A-2?

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KNIFE MAKER
Hey guys I'm wondering if there is any kind of grain direction to o1 and a2. I buy flat ground stock but would like to buy it 6" wide so I can make knives from it either direction. The 6" direction would be cross from the grind direction. I do not know how they make this stuff but my understanding is that it is fairly homogeneous.

Thank you

Ted
 
i have found with Starrett O1 that as you sand thru the first layer of 'grain' you find a second layer running 90 degrees to the first. also some tool steel is 'cross rolled' when the sheets are formed, first rolled top to bottom then right to left.
 
We should be very careful to distinguish between the anisotropic flow lines of the steel (like the wood had grain) any anything having to do with the crystalline (e.g. austenite) grain, which is much less directional and can be altered with basic heat treatment. If the steel was made in the traditional melting, pouring and casting methods then it will be anisotropic in nature. CPM and similar process can overcome anisotropy to some extent. Most O-1 I have dealt with is very anisotropic (directional). The anisotropy will only really show itself heavily in certain properties. Impact toughness, or tensile strength are two that will be heavily affected while abrasion resistance martensitic hardness and others may not even be noticeable.
 
Kevin,
would that mean that the rolling of the steel initially would follow the length? Then making a 6 inch blade from the width of a 6"x18" flat ground piece would not be the ideal way to utilize the material?
 
Scott,

Do the different MFGs mark when they cross roll the material? That would sound like the best way to produce?
 
When the steel ingot was cast the voids, segregations and inclusions were isotropic in nature, i.e. no direction differed much from any other. The rolling process mashed it all down and drew it out in the direction if rolling and made it anisotropic in nature. Properties that will measure differently across the width versus with the length are:


Impact toughness- the blade will have a lower impact toughness if it is cut out from across the width of the piece rather than along the length.

Minor edge stability- on very fine polished edges the anisotropic properties could lead to a toothier edge when cut from the width rather than the length. This may be fine for skinning or meat slicing, but will be miserable for very smooth fine cuts like razors, and the edge will tend to wear less evenly microscopically.

Tensile strength behavior- a sample cut across the width will enter shear based deformation mode differently and neck abruptly before ultimate strength limit is reached. One that is cut with the length will stretch with more subtle necking and probably elongate further from more movement into shear deformation before ultimate strength limit is reached.

If alloy banding is present that pattern will travel across the blade rather than along its length.


Off the top of my head, these are the properties that will show the most, it is up to you whether they are a deal breaker in the final knife and its use. Most require the destruction of the material to really be noticeable but to some that may be enough.
 
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Thank you for the clarification Kevin! I guess I was mistaken. Awesome info to have. Is there a way to tell the direction of the anisotropic flow before cutting into the steel, or even after for that matter?
 
Jess...my instinct was it didn't matter also...which is why I cut first and asked second...lol. Then I got to thinking about how "grainy" cold-rolled 1018 is and 12L14...and it started to bug me. With the knowledge level available on this site it is foolish for me not to ask when something starts niggling at my thinking.

Kevin...thank you very much for the feed back!

I will finish these few knives as two are camp knives and the other is a skinner. I need heat treating practice and grinding practice so these will fit the bill...the next batch will be running the right direction. I wonder how many blades have been sold without grain consideration...lol?
 
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I must admit when I first saw this thread I thought the subject was like the elusive left handed monkey wrench or the blue handled board stretcher!! You know blowing smoke up someones ...........! I have never thought of grain in steel!!

It was only when Kevin Cashen, mentioned that there is such a thing, that my mind entertained the idea! After reading his post again I am really not sure how big a roll grain in steel really plays but, it opens the mind to new ideas and concepts!

When the steel ingot was cast the voids, segregations and inclusions were isotropic in nature, i.e. no direction differed much from any other. The rolling process mashed it all down and drew it out in the direction if rolling and made it anisotropic in nature. Properties that will measure differently across the width versus with the length are:


Impact toughness- the blade will have a lower impact toughness if it is cut out from across the width of the piece rather than along the length.

Minor edge stability- on very fine polished edges the anisotropic properties could lead to a toothier edge when cut from the width rather than the length. This may be fine for skinning or meat slicing, but will be miserable for very smooth fine cuts like razors, and the edge will tend to wear less evenly microscopically.

Tensile strength behavior- a sample cut across the width will enter shear based deformation mode differently and neck abruptly before ultimate strength limit is reached. One that is cut with the length will stretch with more subtle necking and probably elongate further from more movement into shear deformation before ultimate strength limit is reached.

If alloy banding is present that pattern will travel across the blade rather than along its length.


Off the top of my head, these are the properties that will show the most, it is up to you whether they are a deal breaker in the final knife and its use. Most require the destruction of the material to really be noticeable but to some that may be enough.

However I must say this. When I first got started, a seasoned knife maker reached out to me. I like to call him my adopted mentor! He was trying to relate to me some truths and myths that some people have out there, in the knife making game.

He then told me if I saw anything from, two knife makers, to pay attention to that info! Kevin Cashen was one of those names!!

So when Kevin speaks he has my attention. That doesn't mean I may not have to go back and re-read what he said a couple of times to be sure I understand it!! :les:

I once posted a couple of questions I had about steel and quenching and why it worked that way. Kevin joined in on the the thread and posted a couple of comments and began to educate me on what I had asked and why it worked that way!
Kevin said, he usually tried to stay out of discussions and just moderate. He went on to further clarify the answers to my questions! He said, I asked some of the best questions! That to me was something that made me feel not like such a dummy!! I am one of those people who not only wants an answer but, I feel I have to know why it is that way! Once again he is educating me and others!!

This is an interesting subject!!
 
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I must admit when I first saw this thread I thought the subject was like the elusive left handed monkey wrench or the blue handled board stretcher!! You know blowing smoke up someones ...........! I have never thought of grain in steel!!

It was only when Kevin Cashen, mentioned that there is such a thing, that my mind entertained the idea! After reading his post again I am really not sure how big a roll grain in steel really plays but, it opens the mind to new ideas and concepts!



However I must say this. When I first got started, a seasoned knife maker reached out to me. I like to call him my adopted mentor! He was trying to relate to me some truths and myths that some people have out there, in the knife making game.

He then told me if I saw anything from, two knife makers, to pay attention to that info! Kevin Cashen was one of those names!!

So when Kevin speaks he has my attention. That doesn't mean I may not have to go back and re-read what he said a couple of times to be sure I understand it!! :les:

I once posted a couple of questions I had about steel and quenching and why it worked that way. Kevin joined in on the the thread and posted a couple of comments and began to educate me on what I had asked and why it worked that way!
Kevin said, he usually tried to stay out of discussions and just moderate. He went on to further clarify the answers to my questions! He said, I asked some of the best questions! That to me was something that made me feel not like such a dummy!! I am one of those people who not only wants an answer but, I feel I have to know why it is that way! Once again he is educating me and others!!

This is an interesting subject!!

Thank you for the kind words sir, it always registers strongly in my heart to hear that anything I have to offer has helped others in our journey; I also need to send out a warm thank you to your mentor, his confidence in my information is inspiring.

On the topic of the directional properties of steel, it is best observed in extreme cold working, which is very anisotropic. Wrought iron is like an exaggerated caricature of steel with directional issues and when you cold-work it frays almost like a cable; if you score it and bend it like you are going to break it, it will look like string cheese in the inside surface. If you cold-work steel until it fails the lines of failure will be lengthwise, in the direction of working, to a lesser degree but similar to the wrought iron.
Here is a clearer example:

flowlines.jpg
These are images of O-1 tool steel, and a good batch at that. The image on the left is an overall picture of how the material consists of line of flow that run in the direction of the mill rolling operation. This “grain” direction has nothing to do with the actual grains that make up the phases of the steel, which is illustrated by the image on the right. The image on the right is the same steel at over 400X where you can see that within the larger flow lines are the phases (martensite, carbide, ferrite, austenite, etc…) made of what the actual crystalline grains of the steel. The crystalline grains are more isotropic, in that with heat treatments we can remake them and alter their orientations. But you can also see how the larger anisotropic flow lines of the steel can have an influence on the directional properties of the phase grains as well. No matter how you look at it steel is really cool stuff with all it has going on.
 

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I'm pretty careful to not "blow smoke"...Lol. I have worked with tool steel, stainless steel, aluminum, etc for just over 40 years. Usually If I ask a question it is based upon something I know about something similar. ANYTHING cold or hot rolled has a direction. I was not sure how this steel is....produced rolled? Cast? powered?. The steels I have chosen to work with are A-2 and O-1...both a favorite of tool and die shops. Both of which I have had years of basic experience with. So, a good start for me in knife making. In fact A-2 is such a good steel I can't imagine needing anything different ever...except curing boredom with one material...lol. So in general I try to ask things I need to learn...my dilemma here was, while I knew about grain direction in rolled material I was lulled by the homogeneous grain structure of these two steels into thinking perhaps they are not rolled or it just didn't matter after heat treat. Not having the experience to make that call I hoped that Kevin would be the one to put it to rest...lol. And he did. (thank you Kevin)
So much to learn.....

...and You, Mr. Craft, are definitely no dummy....:1:

Kevin, I notice even at the 400 mag I can still see a somewhat linear direction to the gold and black (blurring my eyes a bit to ignore facets) That would be the "toothiness" you spoke of earlier? Anyways...you will all be pleased to know my blades now come from the stock the correct direction. Lol...

Thank you again for your excellent info!
 
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...Kevin, I notice even at the 400 mag I can still see a somewhat linear direction to the gold and black (blurring my eyes a bit to ignore facets) That would be the "toothiness" you spoke of earlier? ...

The directional properties tends to create zones if differential formation of the phases, often carbide precipitation. This will cause slightly different levels of abrasion resistance and even varying strength levels, that could wear just a little differently in sharpening, but even more so in use, so that you end up with a "toothy" effect. This is the same effect you get with Damascus on edge properties. It can be a plus on soft fibrous materials like meat, fine cloth, paper etc... but is not so great in really fine push cuts and harder materials.
 
Out of curiosity, would you be willing to share the second name you were given? I have a suspicion who it may be.

I must admit when I first saw this thread I thought the subject was like the elusive left handed monkey wrench or the blue handled board stretcher!! You know blowing smoke up someones ...........! I have never thought of grain in steel!!

It was only when Kevin Cashen, mentioned that there is such a thing, that my mind entertained the idea! After reading his post again I am really not sure how big a roll grain in steel really plays but, it opens the mind to new ideas and concepts!



However I must say this. When I first got started, a seasoned knife maker reached out to me. I like to call him my adopted mentor! He was trying to relate to me some truths and myths that some people have out there, in the knife making game.

He then told me if I saw anything from, two knife makers, to pay attention to that info! Kevin Cashen was one of those names!!

So when Kevin speaks he has my attention. That doesn't mean I may not have to go back and re-read what he said a couple of times to be sure I understand it!! :les:

I once posted a couple of questions I had about steel and quenching and why it worked that way. Kevin joined in on the the thread and posted a couple of comments and began to educate me on what I had asked and why it worked that way!
Kevin said, he usually tried to stay out of discussions and just moderate. He went on to further clarify the answers to my questions! He said, I asked some of the best questions! That to me was something that made me feel not like such a dummy!! I am one of those people who not only wants an answer but, I feel I have to know why it is that way! Once again he is educating me and others!!

This is an interesting subject!!
 
"So when Kevin speaks he has my attention. That doesn't mean I may not have to go back and re-read what he said a couple of times to be sure I understand it!!
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"

Me too C Craft....He puts things as simple as can be but the subject itself isn't always simple.....sometimes I make a print-out to read while I'm working...lol.
 
Could someone please explain what "cross rolling" is, and at what part of the process it is employed.

Thanks, John
 
Scott Livesey was the first one to put it on my radar...lol. One of the steel companies I was searching material from a couple days ago had a short explanation. basically it was something along the line as: when they are producing the stock (at the steel mill not knife maker's shop) instead of just rolling out the length to get to the thickness desired, they change direction of the rolling to minimize grain direction. so think of silly putty...if you put some dots on it with a sharpy and then began to stretch it in one direction you would end up with lines. if you stretched in in multiple direction the dot would most likely disappear...as there would be no direction to the material's grain....this is a crude analogy for visualization. I think Scott was able to see direction change as he went through the material (Starrett brand O-1 iirc) I think that could possibly be problematic...that makes me think of plywood rather than homogeneous material approaching powdered metal status.

...and rather than listening to my half baked theories...maybe Kevin Cashen could enlighten us on this one? Lol...
 
...and rather than listening to my half baked theories...maybe Kevin Cashen could enlighten us on this one? Lol...

No, it is all in the presentation, if I have learned anything from the knife business it is that when the cake comes out half baked you simply point out how much moister your cakes are:3:.
 
regardless of how much moister my cakes are than yours...I didn't want to lead the OP astray if my understanding/analogy was off a bit...Lol. Cross rolling is a new technique to my understanding.
 
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