There are many types of galvanized steel sheets used in automobiles and household appliances. According to different galvanizing and galvanizing components, there are galvanized sheet, hot galvanized sheet, 64 $ 13 alloy plate and 64 $ S8 alloy plate. At present, the domestic and foreign research on galvanized steel spot welding can be mainly summarized from three aspects to consider: First, galvanized steel sheet material itself from the performance (such as galvanized layer thickness, composition, morphology, surface state) Spot welding process and the performance of the solder joints; Second, from the galvanized steel spot welding process parameters, spot welding equipment (control performance); Third, the use of the electrode material from the impact of the electrode shape consider.
The welding field of galvanized steel in the United States has been studied systematically. The changes of nugget formation and growth process of uncoated steel plates, electro-galvanized steel sheets, hot-dip galvanized steel sheets and hot-dip galvanized steel sheets were compared and the effects of various galvanized steel sheets Thickness of the required welding current range, the study shows that: the same thickness of the coating, electro galvanized steel plate required for welding the largest, followed by hot dip galvanized steel, alloy steel plate required for welding the smallest current. The effects of the coating on the electrode are studied. The results show that the wear rate of the electrode is different and the wear degree is related to the melting point, resistance and welding current of the coating because of different degree of alloying reaction between different coating materials and electrodes. The results show that the electrode wear of electro galvanized steel sheet is the slowest, followed by diffusion galvanizing and electro-galvanized steel sheet. Electrode wear of the hot-dip galvanized steel sheet is the most serious.
For spot welding of hot-dip galvanized steel, it has been considered necessary to use large electrode pressures to extrude zinc from the nugget area, but on the other hand, too high electrode pressure can lead to excessive indentation, The surface of the zinc will be all squeezed out, so as to become the source of future corrosion pit. In fact, most modern spot welding techniques are based on computer-controlled welding and use solid-state current contactors (SCRs), which can make the welding process more accurate and more reasonable.