Microstructure and Mechanical Properties of Dissimilar TC4 Titanium Alloy/304 Stainless Steel Joint Using Copper Filler Wire

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 50; no. 2; pp. 688 - 703
• Main Authors: Hao, Xiaohu, Li, Peng, Xia, Yueqing, Dong, Honggang, Wang, Pengxiao, Yan, Dejun
• Format: Journal Article
• Language: English
• Published: New York Springer US 15.02.2019; Springer Nature B.V
• Subjects: Animal behavior; Austenitic stainless steels; Characterization and Evaluation of Materials; Chemistry and Materials Science; Chromium; Copper; Ductile-brittle transition; Fracture mechanics; Gas tungsten arc welding; Intermetallic compounds; Iron; Low currents; Materials Science; Mechanical properties; Metallic Materials; Microhardness; Nanotechnology; Silicon; Stainless steel; Structural Materials; Substrates; Surfaces and Interfaces; Tensile strength; Thermophysical properties; Thin Films; Titanium alloys; Titanium base alloys; Welded joints; Welding current; Wire
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-018-5031-3

TC4 titanium alloy was successfully welded to 304 stainless steel using gas tungsten arc welding with a CuSi3 filler wire. The Ti/weld transition zone in the joint consisted of β-Ti, Ti 2 Cu, AlCu 2 Ti, TiCu, and Ti 5 Si 3 intermetallic compounds (IMCs) when welded with low current. As the welding current increased, more Fe dissolved into the weld pool, and massive ternary Ti-Cu-Fe and AlCu 2 Ti IMCs formed in the Ti/weld transition zone. The segregated Ti 5 Si 3 phase disappeared, and complex Fe-Ti-Si-Cr IMCs formed outside the Ti/weld transition zone. The microhardness was much higher in the Ti/weld transition zone than that in the TC4 substrate and copper weld, reaching a maximum value of 619 HV. The highest tensile strength was 328 MPa when the welding current was 120 A and the traveling speed was 4 mm/s. All joints failed through the Ti/weld transition zone, and brittle cleavage features were present on the fractured surfaces. Due to the large difference in thermophysical properties between the two base metals, cracks were easily generated, which restricted the improvement in the tensile strength of the TC4/304 SS joint.