[TheForge] Re:packing

Sun Nov 13 16:35:36 EST 2005

most of the time it is much more effective to normalize the blade several 
times, to thermally refine the grain size.
Aus forging isn't as effective at reducing grain size and you can induce 
micro stress fractures that can seriously degrade the blades performance.
Chuck
----- Original Message ----- 
From: "Grant R. Marcoux" <gblacksmith at alamedanet.net>
To: <mspencer at tallships.ca>; "Sponsored by ABANA" <theforge at mailman.qth.net>
Sent: Saturday, November 12, 2005 11:07 PM
Subject: RE: [TheForge] Re: Test mail


> Mike:  Interesting note.  I have heard that there is commonly sulfur
> contamination in large steel melts and that the manganese is added to
> essentially neutralize the contamination.  I have also heard that sulfur 
> is
> very deleterious to nickel bearing tool steels.  I wonder if steels like
> nickel bearing L-6 would be compromised in a coke fire.....
>
> On the issue of "packing"......I was taught bladesmithing by a man named
> Karl Schroen, who described to me a technique called "aus-forging"  Karl
> explained that in aus-forging, you work the blade, especially the edge, at 
> a
> temperature just below the usual forging range.  The German word "aus"
> refers to that which is "out"; in this case "out" of normal temperature.
> Aus does not refer to austenite.
> Karl went on to explain that the steel is not "packed"; but the grains are
> rendered finer and are arranged in a more symmetrical manner.  He learned
> this technique from his grandfather, who was evidently a 19th century 
> smith
> trained in Germany.
>
> Grant
>
>
>
>
> -----Original Message-----
> From: theforge-bounces at mailman.qth.net
> [mailto:theforge-bounces at mailman.qth.net]On Behalf Of Mike Spencer
> Sent: Friday, November 11, 2005 3:59 PM
> To: theforge at mailman.qth.net
> Subject: [TheForge] Re: Test mail
>
>
>
>> Any form of cold work breaks up the large crystals into smaller
>> ones.
>
>
> I'm not a metallurgist, either.  Not even a chemist, just a former
> one.  So I'll *try* not to say things that I know that ain't so. :-)
>
>
> There are two major and  different elements of structure in steel:
>
>     The crystal lattice, which is highly but not perfectly regular.
>     The crystal lattice contains iron atoms and may contain other
>     kinds of atoms is some tidy, regular arrangement with the iron
>     atoms.  This is what's *inside* the grains.
>
>     The grain structure which, although very organized, has a lot of
>     random, swirly [1] quality about it.  The spaces between grains
>     may contain all kinds of helpful stuff or pernicious crap.
>
> So far as I know, gentle cold working doesn't change the grain
> structure.  You have to get it hot or stress it really hard -- put in
> a lot of energy -- to change the grain structure.
>
> But cold working *can* change the crystal structure.  The crystals are
> highly regular, like 3D matrices of TinkerToys(tm).  But they tend to
> have defects, as if you were trying to build a big 3D TinkerToy matrix
> with the help of three hyper-active six-year-olds: most of it will be
> properly connected but various regions won't match up right.  Unlike the
> TinkerToy model, when you stress the steel, those defects can move
> within the crystal, a mis-aligned bond changing to a tidy one and
> passing the mis-alignment on to its neighbor.
>
> Somebody who knows more than I can tell us just how this affects
> toughness, hardness etc.
>
> The stuff between grains makes a big difference to steel properties.
> When I visited the Sydney (NS) steel mill, the guys blew out the plug
> on the open hearth furnace and started tapping the molten metal into a
> big pot hanging in a gantryway.  Then a couple of them went out on a
> catwalk and casually tossed in a few 50# or 100# sacks of lumpy stuff.
> Our engineer guide said that it was manganese.  If I recall correctly,
> he said that there was sulfur dissolved in the iron and as it cooled
> it would be incorpoarated in the crystal lattice and make the steel
> brittle.  The manganese replaced the sulfur, forcing it to the grain
> boundaries, and eliminated that problem. [2]
>
>> This sort of thing happens all the time. Isn't this just semantics?
>
> Yeah, and interesting semantics.  Old Lefty Griswold assured me that a
> broken crankshaft broke because it had "crystallized".  Lefty never
> finished high school but he had 40 years of working on engines from
> the 20s to the late 60s.  He could recognize *something* about the
> appearance of the fracture surface that was, in his experience,
> consistent with fatigue failure.  No use to explain to him that *all*
> steel was crystallized; that wasn't what he *meant*.
>
> So I'm willing to believe that guys who made knives with materials
> available before, say 1940 or 1890 or whatever, gained something
> (perhaps only on average, some of the time) from the move they called
> "packing".   Bert Shaw, Ph.D., the guy who got me interested in all
> this stuff, told me about packing a knife edge.  He would have learned
> the craft around 1915.
>
> My 2 cents worth.  May be over-valued at $0.02. :-)
>
> - Mike
>
> [1] One them technical terms, dontcha know.
>
> [2] Have I got that right?  It was years ago.  Correction welcome.
>
> --
> Michael Spencer                  Nova Scotia, Canada       .~.
>                                                           /V\
> mspencer at tallships.ca                                     /( )\
> http://home.tallships.ca/mspencer/                        ^^-^^
>
> --
>
>
>
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