Effect of Holding Time on Microstructure and Mechanical Properties of K452 Superalloy Brazed Joints

  Vacuum brazing of K452 superalloy was performed with cobalt-base filler metal and nickel-base superalloy powder under brazing conditions of 1170/10min, 1170/60min and 1170/120min respectively. The microstructure of brazed joints was analyzed by using SEM and EDS, and the high-temperature mechanical properties were also studied. The results show that the sound joints with fine microstructure and rare pores are achieved under 1170/60min brazing procedure, due to the good quality of interface. The joints braze under 1170/120min show the highest mechanical properties because of better interface quality, the average 900 tensile strength of 400MPa and 900/100MPa stress-rupture life of 141h/55min. But there morepoles are presented, and many white particles of compound congregated and grow up between the nickel-base superalloy powder in the brazing seam.