Quote:
Originally Posted by redmodelt
I read something on the annealing process when spinning brass which may apply. The brass is annealed before starting the spinning process. As work progress it may need to be re-annealed several times as it work hardens. The steel tube may be the same thing. While it starts out bendable as it goes through the bending process it self work hardens. My observations has been that while bending a steel tube, bends easy at first, but not so much to un-bend. Could have something to do with stretching the molecules, so no longer elastic.
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Yep, that's my take on it also.
So it seems that the 'hard' state of the original tubes was an unintentional result of the tube forming process. Heating and quenching may have contributed to the hard state of the original tubes as well.
Its interesting that the repop suppliers have elected to deliberately harden the entire tube after forming. I've cut some of these tubes up to reform them...there is no doubt that the repop tubes are full-hard.
Unless someone chimes in with a reasonable response I see no reason why the tubes cannot be made from annealed steel. The only difference in making tubes with todays annealed steel is that after forming, most of the tube remains soft-ish (that's what my samples did anyway).
This solves a key issue with my fuel valve project. I hope to have more good news soon.