6.3.1 Nirvana once more
|Did you get what I did in the preceding chapters? Did you notice that I quietly and unobtrusively changed the topic? I moved from nirvana considerations to real life where nirvana is rarely achieved.|
for all materials, including iron and steel, is this best-of-all states, the
best way to arrange your atoms. Or, if you want to read the more
again: the state with the absolute minimum of the "free enthalpy" or
simply "thermodynamic equilibrium".
For a piece of pure iron, nirvana would imply an infinitely large perfect single crystal containing only the required number of vacancies if it has some temperature.
|For a piece of
carbon steel, i.e. iron plus about 1 wt% carbon in the iron, nirvana would be
the basic structure as outlined in the phase diagram. It would consist of a
perfect ferrite single crystal with just
one and then
necessarily big iron carbide
(Fe3C, called cementite) precipitate in it. No grain boundaries, no
dislocations, no nothingexcept the required vacancies according to
temperature and a very few atomically dissolved carbon atoms according to the
Let's CAPITALIZE this:
|In other words: From the phase
diagram we know what (structure-wise) the steel should be.
We also know what you should be and a lot of people have told me what I should be. Worse, some people never tire to tell me this every day (Daddy, don't drink so much beer!). The problem is: I'm just not what I should be, and I never will be. I suspect the same is true for you.
|I do try do improve, however. At
least that's what I tell others. But despite strong or feeble efforts, we never
seem to quite get there.
The problem is that in order to get more perfect, we must change something. This requires some effort and some time. Even if I seriously start dieting, I will not lose excess material over night. It takes time and energy to get results. If you need to lose a lot of surplus you, it takes more time and energy.
|How hard we try to get better depends on the magnitude of the "driving forces" we experience. If you cough a lot and your doctor tells you that you are developing lung cancer, the driving force for quitting smoking is a lot stronger than when you feel in top conditions.|
|The grand total of this little
|Crystals are no smarter than most
humans and behave as outlined above. The big differences to humans are:
|Take your average steel crystal. It's
a poly crystal for reasons
discussed, and it is full of dislocations for many possible reasons. Maybe
because you, the smith, beat it up.
Its surplus carbon may have precipitated. If so, it's certainly not just one big lump but many smaller ones.
|In other words: our
average real steel crystal is not enjoying
nirvana at alljust like you and me. It is trying to achieve nirvana,
howeverjust like you and me. It will never quite reach itjust...
OK. you get the point. To drive that point home, let's reconfigure the list
|All in all, the pathway of a material
to nirvana is a process, too. Things need to change and for a crystal that
means that its structure needs to change. This can only happen if the
distribution of its atoms changes and that involves that atoms move.
Here we go again. But now we know a thing or two and can give the kinetics of sword making a closer look.
|In the preceding chapters I have inched more and more away from just looking at nirvana and moved closer and closer to processes and their kinetics. For the rest of this book that will be our main topic. There is a simple reason:|
|Did you ever notice that in all
medieval paintings depicting heaven and
hell, it is always far more lively down in the pit?
OK, it's hot and doesn't smell so good but at least there is some action. How
long can you take it to sit on a cloud in a white night gown, singing hosanna,
and not doing much else? In particular not doing a bit of sinning along the
time-honored wine, women and song line? Right. Me neither.
And let's not forget that members of the other sex, who are very pious and close to God / nirvana, are usually boring if not outright useless already in this life for what you may have in mind.
|It's the same thing for steel.
Nirvana steel is bad steel as far as sword making is concerned. However, steel
far off the nirvana state is not necessarily good sword steel either. While
there is only one proper nirvana state,
there are zillions of non-nirvana states and some are better than others for
what we have in mind.
It is a little bit like women. Most are not perfect (fortunately) but what kind of non-perfection is best for you depends on what you want to do. Conceive and raise a true-blooded heir? Have an intellectual discussion about gender mainstreaming? Getting your laundry done? Engage into you-know-what, possibly repeatedly, without generating heirs of any kind? That's why in the good old times the sword bearers often had several ladies in attendance. Nowadays we have at least several kinds of steel.
|So what the modern
|Unfortunately, this didn't help you,
the ancient smith, very much. Mostly because you didn't even know what steel
is. What you, the ancient smith, needed to
|What I am are going to do now, schlepping you along if you like, is to look a bit more closely into the kinetics of steel making.|
© H. Föll (Iron, Steel and Swords script)