Influence of the titanium inoculation on the melting behavior and microstructure of Ni 620/X38CrMoV5-1 brazing joints

Since the emergence of the first Ni-based filler metals in the end of the 1940s, the formation of brittle phases due to the metalloids Si, B, and P has been a major challenge. A new approach to selectively manipulate the microstructure of brazing joints with Ni-based brazing alloys is to inoculate the brazing alloy with Ti. The aim of this study is to characterize the influence of Ti on the melting behavior and brazeability in brazed joints consisting of hot-work tool steel X38CrMoV5-1 and inoculated Ni-base brazing alloy Ni 620. For this purpose, the melting behavior of the brazing alloy in the inoculated and noninoculated state is investigated by means of combined differential scanning calorimetry (DSC)/thermogravimetric (TG) analysis. In addition, the flow behavior of the filler metal as well as the resulting microstructure are evaluated by means of acoustic microscopy and scanning electron microscopy on the basis of a special specimen shape. The results show that Ti inoculation has a significant influence on the melting behavior as well as on the flow behavior and the microstructure in this brazing joint. (© 2021 The Authors. Advanced Engineering Materials published by Wiley-VCH GmbH)