Effect of Welding Speed and Post-Weld Heat Treatment on Microstructural and Mechanical Properties of Alpha+Beta Titanium Alloy EB Welds

Effect of Welding Speed and Post-Weld Heat Treatment on Microstructural and Mechanical Properties of Alpha+Beta Titanium Alloy EB Welds

The current work aims to examine the influence of various welding speeds (500, 700, and 800 mm/min) on the microstructure and mechanical characteristics of electron beam-welded Ti-6Al-4V alloy joints. The base metal microstructure was composed of a slightly elongated α phase and a transformed β phas...

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Bibliographic Details
Published in:Fusion science and technology 2024-02, Vol.80 (2), p.166-177
Main Authors: K, Vamsi Krishna, C, Gopi Krishna, Rehman, Ateekh Ur, Nagumothu, Kishore Babu, Talari, Mahesh Kumar, Srirangam, Prakash
Format: Article
Language:eng
Subjects:
Electron beam welding
hardness
mechanical properties
microstructure
Ti-6Al-4V
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Summary:The current work aims to examine the influence of various welding speeds (500, 700, and 800 mm/min) on the microstructure and mechanical characteristics of electron beam-welded Ti-6Al-4V alloy joints. The base metal microstructure was composed of a slightly elongated α phase and a transformed β phase, whereas the fusion zone (FZ) exhibited an acicular martensitic α′ microstructure. This is due to faster cooling rates in the FZ associated with electron beam welding. The welds prepared with a 800 mm/min welding speed showed higher strength and lower ductility [yield strength (YS): 959 ± 6 MPa, ultimate tensile strength (UTS): 993 ± 5 MPa, percent elongation (%El): 8] compared to those prepared with 500 mm/min (YS: 909 ± 4 MPa, UTS: 956 ± 5 MPa, %El: 11). This was due to a decrease in the width of the α-platelets in the FZ owing to faster cooling rates at higher welding speeds. For all welding speeds, samples that underwent post-weld heat treatment (PWHT) displayed a noteworthy reduction in both UTS and hardness values compared to all the as-welded samples. However, the welds at lower welding speeds showed lower strength and higher ductility (YS: 868 ± 5 MPa, UTS: 922 ± 4 MPa, %El: 13) compared to higher welding speeds (YS: 892 ± 5 MPa, UTS: 938 ± 6 MPa, %El: 9) after PWHT. This is due to the formation of the diffusional product α + β phase in the FZ, as evidenced by the transmission electron microscope results.
ISSN:1536-1055
1943-7641