Diffusion brazing of Inconel 617 and 321 stainless steel by using AMS 4772 Ag interlayer

The diffusion brazing of Inconel 617 and AISI 321 stainless steel was carried out with a 50 mu m thick AMS 4772 Ag interlayer at a constant brazing temperature of 750 degrees C under a variable holding time (30 & 60 min). The microstructure of the diffusion-brazed joints was studied in detail via the use of a scanning electron microscope and energy dispersive spectroscopy. The shear strength and fracture behavior of the joints were investigated. Void-free diffusion-brazed joints were obtained due to the capillarity effect of Ag and a more uniform reaction layer was obtained in the joint with a higher brazing/holding time. The joint with a prolonged brazing time of 60 min has the maximum shear strength of 322.9 MPa and an improvement of 26 % over the joint processed at 30 min. The predominant brittle (fracture) failure in the sample processed at 30 min brazing/holding time was responsible for its weak shear strength. At effective brazing/holding time, the use of the AMS4772 Ag interlayer has been effective in joining the IN617 and AISI 321 SS alloys.

Automated summary

The diffusion brazing of Inconel 617 and AISI 321 stainless steel with a 50 µm thick AMS 4772 Ag interlayer at 750°C resulted in void-free joints, with longer holding times leading to a more uniform reaction layer. A joint brazed for 60 minutes had the highest shear strength of 322.9 MPa and a 26% improvement over the joint brazed for 30 minutes.