Diffusion in Electrodes Used for Resistance Spot Welding of Galvannealed Steel

Autor: M. P. Guerrero-Mata, Tamás Réti, Rafael Colás, P. Zambrano, Imre Felde, Mihály Réger, Maribel de la Garza Garza
Rok vydání: 2010
Předmět:
Zdroj: Defect and Diffusion Forum. :300-307
ISSN: 1662-9507
Popis: A study was carried out on Zr-Cr bearing copper electrodes used for resistance spot welding of galvannealed steel strips. One electrode exhibited a series of well-defined layers in which Zn diffused to form β- and γ-brasses; an external layer containing iron was detected in this electrode. Another electrode that exhibited a high degree of damage did not exhibited continuous Zn-diffusion layers in all places, moreover, the Fe-containing layer was either removed, or had it grown to a high extent in some places; the occurrence of Cu-rich particles embedded within the Fe containing layer was observed. Multiple cracks were observed within the γ brass layer in both electrodes. The difference in the observed behaviour of the electrodes can be attributed to a difference in the characteristics of the galvannealed coating of the strips, as the first electrode was used to weld strips in which the layer corresponding to the  phase was well developed, whereas the second electrode was used to weld strips with only an incipient layer. It can be concluded that growth of the  phase changes the thermophysical properties of the zinc coating, affecting the temperature profile during spot welding.
Databáze: OpenAIRE