A Transient Thermal Model for Friction Stir Weld. Part I: The Model

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 42; no. 10; pp. 3218 - 3228
• Main Authors: Zhang, X. X., Xiao, B. L., Ma, Z. Y.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01-10-2011; Springer
• Subjects: Aluminum base alloys; Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Exact sciences and technology; Friction; Friction stir welding; Heat generation; Inverse; Joining, thermal cutting: metallurgical aspects; Materials Science; Mathematical analysis; Mathematical models; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metallic Materials; Metals. Metallurgy; Nanotechnology; Negative feedback; Structural Materials; Surfaces and Interfaces; Thin Films; Welding; Friction Stir Welding; Heat Generation; Friction Coefficient; Negative Feedback Mechanism; Mechanical properties; Friction welding; Welded joint; Friction; Modeling; Transients
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-011-0729-5

Current analytical thermal models for friction stir welding (FSW) are mainly focused on the steady-state condition. To better understand the FSW process, we propose a transient thermal model for FSW, which considers all the periods of FSW. A temperature-dependent apparent friction coefficient solved by the inverse solution method (ISM) is used to estimate the heat generation rate. The physical reasonableness, self-consistency, and relative achievements of this model are discussed, and the relationships between the heat generation, friction coefficient, and temperature are established. The
negative feedback mechanism
and
positive feedback mechanism
are proposed for the first time and found to be the dominant factors in controlling the friction coefficient, heat generation, and in turn the temperature. Furthermore, the negative feedback mechanism is found to be the controller of the steady-state level of FSW. The validity of the proposed model is proved by applying it to FSW of the 6061-T651 and 6063-T5 aluminum alloys.