Microstructure and Mechanical Properties of Ti-6Al-4V Welds Produced with Different Processes
Sakari Tolvanen1, Robert Pederson2, Uta Klement1
1Department of Industrial and Materials Science, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
Materials (Basel, Switzerland)
|February 24, 2024
Summary
Electron and laser beam welding create superior Ti-6Al-4V welds with better mechanical properties and fatigue life. Defects like large or surface pores significantly reduce fatigue performance in these titanium alloy welds.
Area of Science:
- Materials Science
- Mechanical Engineering
- Welding Technology
Background:
- Ti-6Al-4V is a critical titanium alloy used in aerospace and biomedical applications.
- Understanding weld quality is essential for ensuring the performance and safety of Ti-6Al-4V components.
- Different welding techniques yield varying microstructures and defect profiles, impacting mechanical properties.
Purpose of the Study:
- To investigate the influence of welding method on the microstructure and mechanical properties of Ti-6Al-4V welds.
- To evaluate the impact of defects on the fatigue performance of Ti-6Al-4V welds at various temperatures.
- To compare the effectiveness of tungsten inert gas (TIG) welding, plasma arc welding (PAW), electron beam welding (EBW), and laser beam welding (LBW).
Main Methods:
- Fabrication of Ti-6Al-4V welds using TIG, PAW, EBW, and LBW.
- Mechanical testing including microhardness, yield strength, ultimate tensile strength, ductility, and fatigue at room temperature and elevated temperatures (200 °C, 250 °C).
- Metallographic and fractographic analyses to characterize microstructures and identify defect effects on fatigue.
Main Results:
- EBW and LBW produced welds with finer microstructures, superior tensile ductility, and enhanced fatigue performance compared to TIG and PAW.
- Mechanical properties were evaluated across a range of temperatures, highlighting performance variations.
- Large pores and surface-connected pores were identified as critical defects significantly diminishing fatigue life.
Conclusions:
- Electron beam welding and laser beam welding are preferred methods for achieving high-quality Ti-6Al-4V welds with optimal mechanical and fatigue properties.
- Weld quality, particularly the absence of detrimental defects like large or surface pores, is paramount for maximizing fatigue performance.
- The study provides crucial insights for selecting appropriate welding techniques and controlling defects in Ti-6Al-4V applications.
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