fine grain steel

[aldo]

What is the finest grained steel that you guys know of ? and what makes one steel have finer grain than another?

Thanks,
Alex

 

[Stacy E. Apelt - Bladesmith]

Grain is the size of the crystals in the steel.The grain grows depending on temperatures and times of the heat treatment.The larger the grain the more machinable the steel,the finer the harder and tougher.The grain size is what you make it to be.10XX steels have the simplest alloy structure,so I guess you could say they CAN have the fines grain.
Stacy

 

[mete]

Heat treating and alloy content determines grain size .Vanadium is one of the most influential to make fine grain.

 

[Kevin R. Cashen]

There are also two categories of steel based upon the deoxidizing process used in its original creation (melt/pour). Steels that rely upon the addition of silicon for deoxidizing are reffered to as course grained steel, and those that are deoxidized with aluminum are fine grained. But this definition is has more to do with at what temp. and how fast the grains will grow when heated. Fine grained steels will resists growth until a much higher temp is reached but will then rapidly increase grain size. The silicon "course grained" stuff will begin grain enlargement at a much lower temperature but will increase in size slower.

As mete pointed out the addition of heavy carbide formers like Vanadium will really do the trick for keeping grain size small. Each steel will have a grain size that works best for a given application and contrary to popular belief one can get carried away with the fine grain size.

 

[aldo]

Each steel will have a grain size that works best for a given application and contrary to popular belief one can get carried away with the fine grain size.

OK I guess I should say what steel takes the finest(sharpest) edge?

thanks to everyone for your help

Alex

 

[aldo]

Heat treating and alloy content determines grain size .Vanadium is one of the most influential to make fine grain.

So something like s90v with alot of vanadium would have finer grain and therefore the possiblity of a sharper edge?

THANKS

ALEX

 

[mete]

When you see a steel with up to about .50 V ,it's there for grain refinement . For higher amounts anything over .50V is there for formation of carbides.

 

[Stacy E. Apelt - Bladesmith]

mete,What is your take on grain size vs. sharpness.
I feel it is sort of like blond hair.It does make a gal look sharper (bad pun),but there is a whole lot more than just one thing involved.
Stacy

 

[mete]

Grain size vs sharpness ? That I don't know. We worry about excessive grain size since it causes brittleness.We don't want large grains when we form sheet metal since it can give a rough texture surface [ 'orange peel']. In steel we have carbides to think about for sharpness , the finer and more uniformly distributed the better [ CPM steels].

 

[Stacy E. Apelt - Bladesmith]

Thanks,mete.I didn't see any real advantage in fine grain relating to sharpness,either.It won't hurt,but it isn't the biggest thing either.

 

[Kevin R. Cashen]

Bladsmth, thanks for asking mete that question. For what it is worth I concurr with you. One can abraid away a portion of a grain in cutting, polishing or sharpening metal. So I do not see much difference in the obtainable edge. I can see a difference in the edge holding if the grains are large enough to induce weakness, but as mete pointed out carbides are a greater concern for this. I personally feel that uniform grain size is more important than extemely fine. I would rather have all my grains completely uniform, than have a huge variation and uneveness in grain size, regardless of how fine some of them may be.

 

[aldo]

Thanks to everyone this has been very informative. I have heard people say that this steel or that steel seems to take a sharper edge and I was just wondering if grain size has anything to do with it?

THANKS
ALEX

 

[Stacy E. Apelt - Bladesmith]

Aldo - The main difference between steels is in the alloy ingredients,and what properties they give the steel.The edge is a factor of hardness,toughness,wear resistance,flexibility,etc.Gain on one and loose on the other is the usual trade off on steels.You must pick the steel for the job.A shovel can be fairly soft edged,but better be wear resistant.A fillet knife must be both hard edged and flexible.And so it goes.It would be a dull (bad pun) world if there was only one perfect steel.

Thanks Kevin for your take on this,too.I have had a couple of discussions on this topic,and no one seems to have any proof that it matters,but the myth still persists that fine grain equals fine edge.