Effect of interlayer addition on microstructure and mechanical properties of NiTi/stainless steel joint by electron beam welding. (20th January 2021)

• Record Type: Journal Article
• Authors: Niu, H.; Jiang, H.C.; Zhao, M.J.; Rong, L.J.
• Is Part Of: Journal of materials science & technology. Volume 61(2021)
• Page Start: 16
• Page End: 24
• Publication Date: 2021-01-20
• Subjects: NiTi -- Stainless steel -- Electron beam welding -- Interlayer -- Mechanical property; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2020.05.043
• Languages: English
• ISSNs: 1005-0302

Abstract

Abstract: NiTi/Stainless Steel (SS) sheets have been welded via a vacuum electron beam welding process, with three methods (offsetting electron beam to SS side without interlayer, adding Ni interlayer and adding FeNi interlayer), to promote mechanical properties of the NiTi/SS joints. The joints with different interlayers are all fractured in the weld zone near the NiTi side, which is attributed to the enrichment of intermetallic compounds including Fe2 Ti and Ni3 Ti. The fracture mechanisms of different joints are strongly dependent on the types of interlayers, and the joints without interlayer, adding Ni interlayer and adding FeNi interlayer exhibit cleavage fracture, intergranular fracture and mixed fracture composed of cleavage and tearing ridge, respectively. Compared with the brittle laves phase Fe2 Ti, Ni3 Ti phase can exhibit certain plasticity, block the crack propagation and change the direction of crack propagation. The composite structure of Ni3 Ti and Fe2 Ti will be formed when the FeNi alloy is taken as the interlayer, which provides the joint excellent mechanical properties, with rupture strength of 343 MPa.