A Study on the Effect of Process Parameters on the Properties of Joint in TLP-Bonded Inconel 738LC Superalloy

• Published in: Metallurgical and materials transactions. B, Process metallurgy and materials processing science Process metallurgy and materials processing science, 2013-10, Vol.44 (5), p.1222-1231
• Main Authors: Jalilvand, V., Omidvar, H., Shakeri, H. R., Rahimipour, M. R.
• Format: Article
• Language: English
• Subjects: Applied sciences; Bonding; Characterization and Evaluation of Materials; Chemistry and Materials Science; Exact sciences and technology; Joining, thermal cutting: metallurgical aspects; Materials Science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metallic Materials; Metals. Metallurgy; Nanotechnology; Parameter estimation; Solid solutions; Structural Materials; Superalloys; Surfaces and Interfaces; Thin Films
• ISSN: 1073-5615; 1543-1916
• DOI: 10.1007/s11663-013-9883-z

Optimization of transient liquid phase (TLP)-bonding variables is essential to achieve a joint free from deleterious intermetallic constituents and with appropriate mechanical properties. In this study, TLP bonding of IN-738LC superalloy was performed using AMS 4777 filler metal. The influence of gap size and bonding parameters (temperature and time) was investigated on the joint microstructure and its properties. In cases where the holding time was insufficient for complete isothermal solidification, the residual liquid transformed to non-equilibrium eutectic microconstituents consisting of nickel-rich boride, chromium-rich boride, and γ solid solution phases. The eutectic width decreased with the increase of holding time and the increase in initial gap size resulted in thicker eutectic width in the samples bonded at the same temperature and for equivalent holding times. The time of complete isothermal solidification decreased with the increase in bonding temperature to 1100°C, which was consistent with the models based on the diffusion-induced solid/liquid interface motion. Microhardness and shear strength tests were used to investigate the mechanical properties of the bonds. In the bonding condition in which isothermal solidification was not accomplished completely, the eutectic constituent with the highest hardness in the bond region was the preferential failure source. The results showed that homogenized joints had the highest shear strength.