On 25 aug 2011, at 01:56, Don Ordes wrote:
> Mike,
>
> Again, it depends on a lot of things, mostly, the metallurgy and
> forging/bending processes used to create the hook.
>
> Understanding the basic metalurgy is helpful, but it's also somewhat
> practical wisdom. A metal maintains it strength when bending if it can
> return to it's original shape. Bending it beyond that means you 'yield' the
> metal. How far you go past yield will determine how much strength of the
> metal you compromised. If you heat the metal before bending, you are less
> apt to break it, but you will have a more brittle metal once it cools.
Which can be counteracted by correctly retempering ('heat treating') it. Also
remember that bending metal (as in plastically deforming it) 'work hardens' it
in most alloys, meaning that at the bend, the metal will be harder, and more
brittle, from just bending it. Also note that with elastic deformation (like a
spring, where the metal returns to its original shape), comes fatigue, so over
the long run, the statement that with elastic deformation a metal retains its
strength is not entirely correct.
> I'm not too concerned with hook strength for fly-fishing, because the leader
> will always be the weakest link.
Again, not necessarily. carbon-based polymers in fact have potentially a much
higher tensile strength than steel; the ultimate reason for that is that
polymers are defined by the strength of covalent bonds between the carbon
atoms, and metals by so-called 'metal bonds' between the metal atoms. Major
problem is that those covalent bonds only give strength to individual
molecules, but if you can make molecules long enough to benefit from this
strength at the macroscopic level, you have a material with a tensile strength
up to 10 times that of a metal. This is why dyneema and other gel-spun
polyethylene fibers are so strong: optimum individual polymer chain length, and
more importantly, a manufacturing process that maximizes the interaction of
individual polymer molecules with all adjacent molecules in the fiber so as to
retain as much of the intrinsic strength of the molecules in the macroscopic
fiber material.
ANd I'm sure all of us have, at one time, bent or even broken hooks (even hooks
with no prior damage) by just pulling on our line...
> Not many people lift a very large fish out of the water on the hook,
> especially flyfishers. Bait-fishers and lure fishers do it and the gear is
> sized for it.
>
> I had a hook come in a box of Mustads that was way off spec, either for
> metallurgy or tempering. I put it in the vise and it was like a soft
> plastic. I could twist it like a baggie tie and tie it in a knot- it was
> like a stiff piece of string. No other hooks in the box were like that.
FUlly annealed and probably left out of the tempering batch...
>
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| Dr. Henk J.M. Verhaar | e-mail: [email protected] |
| Ecotoxicoloog en vliegbinder | tel: 035 656 2128 |
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| NL-1343 AJ Almere | web: www.xs4all.nl/~flyrod |
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