Interfacial structure and joint strengthening in arc brazed galvanized steels with copper based filler
(1.Provincial Key Laboratory of Advanced Welding Technology, Jiangsu University of Science and Technology, Zhenjiang 212003, China;
2.College of Materials Engineering, Shanghai University of Engineering Science, Shanghai 200336, China)
2.College of Materials Engineering, Shanghai University of Engineering Science, Shanghai 200336, China)
Abstract: Galvanized steel sheets were joined by tungsten inert gas(TIG) and metal inert gas(MIG) brazing process using copper based filler. The results show that the joint zone hardness is higher than that of the base material or copper filler from the microhardness tests of TIG brazing specimens, and the fracture spot is at the base materials zone from the tensile tests of MIG brazing specimens. Examination using energy dispersive X-ray analysis reveals the presence of intermetallic compound Fe5Si3(Cu) in the joint. The dispersal of fine Fe5Si3(Cu) particles is the main strengthening factor for the joint. The Fe5Si3(Cu) particles are determined to arise from three sources, namely, spot micro-melt, whisker-like fragmentation and dissolve-separation actions.
Key words: galvanized steels; CuSi3; TIG; MIG; arc brazing; strengthening mechanism; interfacial structure