Non Destructive Methodology for Parameterization of the Burning Zinc in the Resistance Spot Welding Process

Galvanized steel is used in large numbers, especially in the automotive, for its corrosion resistance and low cost. The welding of these materials, this industrial sector is usually performed through the spot welding process. Depending on the galvanized steel with a film of coating based on zinc is usually used in welding, a technique called burn zinc (zinc burning) to minimize the detrimental effects of zinc in the material during the welding cycle. In this context, this paper studied a non-destructive method, aiming to find an appropriate removal of this layer of zinc, for considering this, the signals generated by a sensor that records the dislodgement during stages of the spot welding, using as a basis the reading of the thermal expansion of galvanized steel sheet. Thus, physical simulation experiments were performed by varying the current and the time for the preheating phase cycle. The responses from the burn zinc generated by the sensor and visual analysis by attribute, were shown in graphs through an operating envelope. Evidence showed that the sign of displacement of the electrode, proved to be an efficient non-destructive method for determining the appropriate parameters in the burn zinc in process of spot welding for galvanized steel plates.

Galvanized steel; Electrode displacement; Burning zinc; Welding point