Dissimilar P-TIG welding between Inconel 718 and commercially pure Titanium using niobium interlayer. (December 2022)

• Record Type: Journal Article
• Authors: Shehbaz, Tauheed; Junaid, Massab; Khan, Fahd Nawaz; Haider, Julfikar
• Is Part Of: Proceedings of the Institution of Mechanical Engineers. Volume 236:Number 6(2022)
• Page Start: 2311
• Page End: 2324
• Publication Date: 2022-12
• Subjects: P-TIG welding -- CpTi -- Inconel 718 -- niobium interlayer -- nanoindentation -- residual stresses -- mechanical properties; Mechanical engineering -- Periodicals; Production engineering -- Periodicals; Manufacturing processes -- Periodicals; 621.05
• DOI: 10.1177/09544089221091388
• Languages: English
• ISSNs: 0954-4089

Abstract

The formation of brittle intermetallics is a challenge for the direct joining of commercially pure titanium (CpTi) and Inconel 718 (IN718) alloy. In the present work, dissimilar weldments using the P-TIG (Pulsed-Tungsten Inert Gas) welding technique were produced, with elemental Niobium (Nb) as an interlayer. The insertion of Nb acted as a barrier and suppressed the interdiffusion of Ti and Ni across the interlayer resulting in no Tix Niy intermetallic compounds (IMCs) at the CpTi/IN718 dissimilar joint. Titanium (Ti) and Nb on CpTi side joined by solid solution (Ti, Nb) strengthening mechanism. Nickel (Ni) joined with Nb at IN718 side via eutectic reaction, where a diffused layer comprising of NbNi3, and Nb7 Ni6 IMCs was found. Owing to the formation of brittle IMCs (NbNi3, Nb7 Ni6 ), the diffused layer at Nb/IN718 interface exhibited the microhardness of ∼782 HV, which is ∼64% higher than the Nb/CpTi interface and considered highest in comparison to the other regions of the joint. The maximum tensile strength of the weldment was 150 MPa, which is significantly less than CpTi (360 MPa) and IN718 (850 MPa) base alloys possibly due to the presence of cracks in the diffused layer and the welded joint.