Soldagem de aço inoxidável martensítico CA6NM por processo GMAW com corrente alternada

Abstract

The abrasive effect of water and cavitation erosion are the mechanisms that wear of turbine rotor blades in hydroelectric plants, that account for the majority of the electricity generated in Brazil. Recently, several technologies of equipment maintenance and efficiency. In turbine rotor blade recovery movements, they are carried out in weld bead packs to fill in roughened parts. A major problem of rotor blade maintenance is a heat transfer medium for the base metal, alloying elements, mechanical strength, roughing resistance, etc. A technique for the low heat transfer is the use of alternating current welding processes, guaranteeing a viable alternative for the dilution of the weld beads, guaranteeing a lower heating. Used a piece of hydraulic turbine rotor (CA6NM stainless steel) as base metal cut into several equal sized parts. For a selection of welding parameters in alternating current, a CCC methodology is used to design the experiment, changing wire feed speed, high current and low current. The increase of the dilution was observed as the feed velocity of the wire increased, causing an increase of the thermally affected zone. Very low wire feed speeds caused zero dilution – lack of fusion - of the weld bead to the base metal. Therefore, GMAW CA process should provide less heat transfer than GMAW standard processes.