Investigating the bonding mechanism of P-TIG welded CpTi/Inconel 718 dissimilar joint with Nb interlayer

Shehbaz, Tauheed, Khan, Fahd Nawaz, Junaid, Massab and Haider, Julfikar ORCID: https://orcid.org/0000-0001-7010-8285 (2022) Investigating the bonding mechanism of P-TIG welded CpTi/Inconel 718 dissimilar joint with Nb interlayer. Materials Letters, 313. ISSN 0167-577X

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Abstract

The direct joining of CpTi and Inconel 718 is challenging due to the formation of brittle TixNiy in the fusion zone. For the TIG welding of CpTi/IN718 joints in the present work, the use of Nb as an interlayer served as a barrier, resulting in the complete suppression of brittle TixNiy which is responsible for immediate failure of the CpTi/IN718 dissimilar joint. The results indicated that solid solution formed towards the CpTi side, whereas eutectic formation (NbNi3, Nb7Ni6) was observed towards the In718 side of the weldment. Owing to these brittle IMCs, a nanohardness of ∼14.62 GPa was measured at the Nb/IN718, which is ∼70% higher than that of the Nb/CpTi interface which was comprised of columnar dendrites. The tensile strength was 150 MPa with the presence of cleavage cracks at the Nb/IN718 interface of the fractured surface.