Composition of BÖHLER metal powders - Tenica

TIG weldingIn the TIG welding process, a burnout of carbon or otheralloying elements doesn't occur because of the argon shieldinggas. The weld metal composition depends on thecomposition of the alloy used and the dilution with the basematerial. To keep the dilution with the base material as lowas possible it is recommended, to sharpen the tip of thetungsten electrode frustum shaped and not pointed as usual.This procedure avoids a strongly concentrated arc, whichwould cause much more melting of the base material andlead to a higher dilution with the welding material. Duringthe overlay process the arc has to be turned towards theliquid weld pool and not to the base material so that a lowerdilution can be achieved.The investigations on the mechanism of pore formationshowed, that during TIG welding the main cause lies in theoxygen content. The shielding gas (argon) prevents oxygenreaching the weld pool during welding. If pore formationtakes place, so this must be seen in connection with an oxidefilm (scale) of the base material and/or with an oxidation ofthe welding rod. Therefore it is important the base materialis cleaned sufficiently and the welding rod does not leavethe shielding gas too early.If necessary, the base material can get buffer layer beforehardfacing.TIG welding with the casting rodBÖHLER Celsit SN.17