MBI wrote:Microscopically speaking it does have a grain, as the atoms line up in a crystalline lattice. It can also be visible macroscopically, without magnification, however I'm no metallurgist so I don't know if that's a visible result of that crystal lattice or if it's a result of how the metal is worked
To expand on that, all metals generally start as a casting of some sort. As metal solidifies the molecules (of iron and carbon atoms and what ever other elements there are) form and then those molecules form crystals. The arrangement of atoms in the molecules has a lot to do with the hardness of the steel, and can sometimes be set by heat treating (given that the right atoms are there). I may have mangled the terminology but that is the gist of it. The smaller the size of the crystals the stronger the metal. There are alloying elements sometimes added to reduce the grain size. There are labs where one can send off samples to be etched and photographed under a microscope to see the grain structure.
To turn a cast piece of metal into thin sheet it is rolled out in a rolling mill (or drawn through a die for wire). As it goes through a mill those crystals will be elongated as the metal gets thinner and longer. The lengthwise stretch of the elongated crystals creates a grain oriented lengthwise. Strength-wise, it is easier to break the bond between grains than to break a grain itself, hence it should have better properties with the grain than 90 degrees to it. In my industry (non-ferrous rolled metals) physical property tests are sometimes specified with the grain and/or against the grain--it means something to metalurgists.
In the context of picks, if one is working with strips of metal (1/2" strips of shim stock, sweeper bristles, etc., the grain should be oriented correctly by default. Steel mills or service centers slit large master coils into smaller width coils and they always slit lengthwise (with the grain). If one is working with sheets, either cutting or stamping out picks or shearing the metal into blanks to then grind, then one should pay attention to the grain. At the same time, lifting a pin should not be that stressful, so I would not throw out any picks made across the grain--it would not likely make any noticeable difference. Maybe going with the grain would allow a pick to be very slightly thinner with the same strength, at any rate it could not hurt.
Metal doesn't have a grain like wood does.
