Influence of vibration frequency on solidification of weldments
Vibration techniques for improving properties of cast metals have been reported for many years. Boyle et al. irradiated molten metal with ultra-sonic waves, determining that ultrasonic vibrations efficiently degas light metals. Later a process was conceived for treating molten metals with high frequency mechanical vibrations. It was found that gas inclusions, dross and slag were brought to the surface by process. This produced uniform, fine grained castings, and increased the toughness, ultimate tensile strength and yield strength of the cast material. With welding, when vibration is applied during the weld process, solidification of the weld pool is affected. As the weld pool solidifies, dendrites can be broken up before they grow to become too large. Consequently, grains are not only limited in size, but dendrites growing perpendicular to the fusion line are curbed. The effect of these phenomena is to partially randomize the direction of grain growth and inhibit segregation in the weld path. This finer microstructure can provide better mechanical properties and eliminate hot cracking sensitivity of the weld. In vibration welding, internal stress is dispersed as it forms. In addition, the microstructure of the weld metal is affected by weld pool disturbances during solidification. Ideally, the entire weldment's residual stress is relieved while at the same time, its microstructure is improved.
- Research Organization:
- I-Shou Univ., Hsiang (TW)
- OSTI ID:
- 20050493
- Journal Information:
- Scripta Materialia, Vol. 42, Issue 7; Other Information: PBD: 17 Mar 2000; ISSN 1359-6462
- Country of Publication:
- United States
- Language:
- English
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