Diffusion brazing of IN718/AISI 316L dissimilar joint: Microstructure evolution and mechanical properties. (September 2020)

• Record Type: Journal Article
• Authors: Binesh, Behzad
• Is Part Of: Journal of manufacturing processes. Volume 57(2020)
• Page Start: 196
• Page End: 208
• Publication Date: 2020-09
• Subjects: Diffusion brazing -- Microstructure -- Mechanical properties -- IN718 superalloy -- AISI 316L stainless steel; Production management -- Data processing -- Periodicals; Manufacturing processes -- Periodicals; Procestechnologie; Productietechniek; Production -- Gestion -- Informatique -- Périodiques; Fabrication -- Périodiques; Manufacturing processes; Production management -- Data processing; Periodicals; 670.5
• DOI: 10.1016/j.jmapro.2020.06.025
• Languages: English
• ISSNs: 1526-6125

Abstract

Abstract: In this study, diffusion brazing was employed to join IN718 superalloy and AISI 316 L stainless steel using MBF-20 amorphous interlayer. The effect of interlayer thickness (50−150 μm) was studied on the microstructure and mechanical properties of the joints. The joints were characterized by using optical and scanning electron microscopes, energy dispersive spectroscopy and X-ray diffraction analysis. Microhardness and shear tests were used to assess the mechanical properties of the joints. The microstructural investigations revealed that eutectic phases including γ solid solution, Ni3 B, CrB, Cr2 B3 and Ni6 Si2 B were formed at the joint centerline of the sample with incomplete isothermal solidification during holding at the brazing temperature. Fine Ni3 Si particles also precipitated via a solid state transformation during cooling in the vicinity of eutectic phases. Mechanism of microstructure evolution and the solidification behavior of the centerline intermetallic compounds were discussed. In addition, Cr-, Mo-, Nb-rich borides precipitated in the DAZ of IN718 side and the precipitates formed in the DAZ of AISI 316 L side were Cr-, Mo-rich and Fe-, Cr-rich borides. The maximum shear strength of 440 MPa was obtained for the sample with complete isothermal solidification. Fractography of the samples after the shearing test indicated that the sample with complete isothermal solidification exhibits a ductile failure mode, however a brittle fracture happens in the samples containing hard eutectic constituents at the joint centerline.