Seam welding electrodes

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Thank you, Tom, for your breif history of seam welding. Another question I'm struggling to find may be a question for a metalurgist. Does grain size in an electrode effect current flow? Would small, uniform grain size produce a different weld than an electrode with large grain (cast structure)?

-- Dennis R. Wootan (dwoo@iquest.net), November 08, 1999

Answers

Dennis, There might be a difference, as a free electron can move in a perfect single crystal lattice without loss of energy. Any disturbance of the crystal structure, any perturbation of the atoms from their lattice sites, will scatter electrons and thereby cause electrical resistance. Impurities, grain bounderies, dislocations, vacancies and other imperfections abound in all normally used materials. In pure metals and dilute alloys the total resistivity is the sum of the thermal component which arises fromthe lattice vibrations and the residual resistivity caused by impurities and structural imperfections. The latter will be different in fine grained versus large grained material. The question is , how much ? You have to try it out. success Henk

-- Henk de Vries (hdvr@wxs.nl), November 08, 1999.

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