How do these come into play? Can they be manipulated to our advantage by forging? Do they follow the profile when the blade is forged to shape?

Tim,
Are you asking about grind lines (where they meet in the middle) or seams from froging?
I'm not familiar with that term, slip lines.
You may be talking about the slip grains of the metal.
(the area between the solid grains)
Maybe the lines between the layers of damascus, for example.
I'm sure Ed is at a show this weekend, and I would like to help, but I'm not sure what you need.
Can you educate me ?

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Let me start over so I dont mess it up.

All iron-carbon alloys are made of cells called body center cubic (BCC) or face centered cubic (FCC). BBC is a cell of eight iron atoms on the corners of the cell and one carbon atom in the center. FCC is a cell where there are the same atoms of iron on the corners but there are 6 carbon atoms. One on each face of the cube. Crystals are groups of these cells stuck to each other in patterns. The crystals are made up of millions of cells but are in straight geometric alignment. The edges or sides of these straight alignments are what I thought were called slip lines. So these crystals are slipping past each other when we forge. Something has to give. So Im wondering if when they give they are also being pushed into a position that follows the profile of a blade that has been forged to shape?

Yes, Slip planes can be manipulated by forging.
Basically, anything you do to the grains, you do to these planes as well.
Forging makes the grains pack tightly together, esspecially along the cutting edge as you pack it.
This is why you do not heat up the blade as hot to forge as you do to weld,(Damascus) The excessive heating will cause grain growth and defeat the packing processes.
The tighter the grains, the tighter the spaces between them,(slip planes), and the better your cut.

Weld in the orangr-yellow range.(upper critical range)
Forge in the red-orange range.(middle of critical range)
Pack in the cherry-to dark range.(low end or below critical range)
Anneal or stress relieve(lower critical- middle range)
Grind and H/T.

Controling the heat, controls the grain growth.
Forging is a machanical way to manipulate the grains, as long as we don't mess it all up by heating it back up too far.

If you are focused on the grains while you work, you will manipulate the slip planes at the same time.

Many people argue that only a forged blade will do, because of the grain packing along the edge allows it to out perform a stock removal blade.(generally speaking)

The ABS focuses on this phenominon.
Extreme control of your temperatures will help you develop this advantage consistantly. Hope it helped.
...........................BE BLESSED!.......................................

Howard Clark wrote quite a diatribe on "edge packing" several years ago... If I remember correctly, the bottom line was, if it *really* occured, you'd have a nuclear explosion.

Thanks Gene and Don!

Hey I agree with Don about the edge packing. Howard did prove that. If it were occuring then why don't my blades worked under my 25 ton press show finer grain than those worked by hand. The original thought of edge packing was that the edge was packed but it was always done at a dull red to black heat which is the normal normalizing temps which also shrink the grain and that is what occurs. So in my opinon a smith cant really affect grain structure and such in the steel with forging other than forging the direction it is going by shaping a blade. The proper thermal cycles are what is important during and after the forging.

Packing isn't really what I was getting at though. I was thinking more in terms of lateral lines that follow the profile forged to shape. Aside from grain size. Grain lines or slip lines. Do they hold their position that follows the profile after a thorough heat treat? You see what Im getting at? I understand that grain size is going to change during the heat treatment and maybe that erases anything that forging did. But if the lines are still there following the profile then theres something that could indicate the possiblity of an mechanical advantage over stock removal.

I agree totally that a forged blade can be structurally more sound, I guess thats how to say it. A good example of the flow of the grain following the knife profile is in damascus. Look at a basic ladder pattern or similar sometime on two knives a stock removal and a forged blade. The damascus on the forged blade will follow the profile if forged correct and on a stock removal knife it will run off the the end. How much more a knife gains from this is hard to say but it must be positive I would think. Just my two cents anyway

I know what your talking about. I have'nt heard the term used in some years, and then only by some of the older smiths I knew. Anyway, to illustrate your point, here are some pics of how the "slip lines" will manifest themselves.........
http://www.caffreyknives.com/forgedblade.jpg
and this classic crankshaft example........
http://www.caffreyknives.com/forgedcrank.jpg

Neat drawings! That helps a lot. Thanks!