EBSD study of dissimilar transient liquid phase joining of duplex stainless steel SAF 2205 to nickel-based superalloy IN X-750

Abstract

SAF 2205 and IN X-750 were joined using the TLP method. The joining process was carried out at 1100 °C for different times using BNi-3 interlayer. Microstructural study and identification of the present phases in the bonding regions were performed using optical microscopy and scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy and electron backscatter diffraction technique. Microhardness and shear strength tests were done to measure the mechanical properties. Different phases such as BN, Ni3B, Ni2B, CrB, Cr2B, and Ni2Si were formed in the bonding area. EBSD analysis results showed that the amount of the formed phases in the bonding area is a function of the bonding time. As the holding time increased, the amount of created phases in the bonding area increased from about 8 to 11 wt.%. The microhardness profile of the joining area also behaved differently as the bonding time changed. The maximum measured microhardness was about 850 HV which appeared in the athermally solidified zone of the bonded sample for 1 min. The maximum shear strength was observed in the bonded sample with complete isothermal solidification, approximately 72% of the shear strength of SAF 2205 and 85% of IN X-750.