Optimization of brazing parameters for 316L stainless steel with AgCuZn filler metal under argon atmosphere

This research studies the optimal parameters for brazing 316L stainless steel using AgCuZn as filler metal under an argon gas atmosphere. The brazing parameters included temperature, brazing time, and argon gas flow rate. The study employed Box-Behnken design for experimental design and desirability function as the optimization tool. Mechanical properties study included the measurements of shear force, microhardness, microstructure, and fracture of brazing joints through a scanning electron microscope (SEM) as well as the chemical composition using an energy dispersive x-ray spectroscopy (EDS). As a result, the temperature and the brazing time significantly affected the shear force of the brazed joint at a 95 percent confidence interval. The optimal condition of the study was 800°C of temperature and a 20-minutes brazing time which caused the maximum shear force at 5,909.1 N. The brazing joint strength was increased when the temperature and time of brazing were increased and reached the optimal point. Microstructure showed a formation of an Ag-rich phase, a Cu-rich equiaxed dendrite phase, and a eutectic Ag-rich phase, which completely combined as the network structure and evenly small fine grains. Moreover, the shear force of the brazed joint was decreased when the temperature and time of brazing exceeded the optimal point due to the grain growth of the interface layer.