| In allusion to the problems of the great effects of spot weld production quantity, large consumption of electrode and electrode surface state on the quality of spot welding in the FAW Mazda Car welding product line. Based on gas cryogenic method, Cr-Zr-Cu spot welding electrodes treated in different temperatures, different holding times of temperature, and different cooling rates can increase the performance of the spot welding electrodes, improve the quality of welding spots and extend the life of resistance spot welding electrodes.Firstly, the impacts of deep cryogenic treatment on the microstructure, the electrical conductivity and the thermal conductivity of the electrode were analyzed. The study found that after deep cryogenic treatment, with cooling temperature fallen and heat holding time extended, Cr and Zr particles separated out by the electrode got larger obviously, and scanning the crystal surface proved the quality percentage of Cr and Zr improved also the electrical conductivity and the thermal conductivity of the electrode enhanced obviously.Secondly, deep cryogenic treatment having the impact on lattice constants and electrode resistance to abrasion were comparative analyzed. The study found that lattice constants of electrode got obvious smaller after–196 centigrade deep cryogenic treatment. After -120 centigrade and -150 centigrade deep cryogenic electrode, the conglutinated scrap-iron was increasing with the cooling rate increasing. After -196 centigrade deep cryogenic electrode, with the cooling rate increasing, its resistance to abrasion was descending, that is the cooling rate is small. being in favor of improving electrode resistance to abrasion and anti-coagulation.Then, using the electrode without deep cryogenic treatment and resistance spot welded electrode through deep cryogenic treatment to carry through welding tests, that conducted to measure the thickness of the joints, the exterior diameter of the joints, the surface of joints and electrode life. Deep cryogenic parameters are as follows: deep cryogenic temperature is -196 centigrade,heat holding time for 6 hours, cooling rate to 6 centigrade per minute. The study found: the thickness of the welded joints would increase with the number of points of the... |
