Investigation of Process Parameters for Friction Stir Processing (FSP) of Ti-6Al-4V Alloy

Abstract: Friction stir welding (FSW) is a relatively new solid-state joining process. This joining technique is energy efficient, environment friendly, and versatile. In particular, it can be used to join high-strength aerospace aluminum alloys and other metallic alloys that are hard to weld by conventional fusion welding. FSW is considered to be the most significant development in metal joining in a decade. Recently, friction stir processing (FSP) was developed for microstructural modification of metallic materials. In this review article, the current state of understanding and development of the FSW and FSP are addressed. Particular emphasis has been given to: (a) mechanisms responsible for the formation of welds and microstructural refinement, and (b) effects of FSW/FSP parameters on resultant microstructure and final mechanical properties. While the bulk of the information is related to aluminum alloys, important results are now available for other metals and alloys. At this stage, the technology diffusion has significantly outpaced the fundamental understanding of microstructural evolution and microstructure–property relationships.

Abstract: Foreword.List of Contributors.1. Structure and Properties of Titanium and Titanium Alloys (M. Peters, et al.).2. Beta Titanium Alloys (G. Terlinde and G. Fischer).3. Orthorhombic Titanium Aluminides: Intermetallic with Improved Damage Tolerance (J. Kumpfert and C. Leyens).4. gamma-Titanium Aluminide Alloys: Alloy Design and Properties (F. Appel and M. Oehring).5. Fatigue of Titanium Alloys (L. Wagner and J.K. Bigoney).6. Oxidation and Protection of Titanium Alloys and Titanium Aluminides (C. Leyens).7. Titanium and Titanium Alloys - From Raw material to Semi-finished Products (H. Sibum).8. Fabrication of Titanium Alloys (M. Peters and C. Leyens).9. Investment Casting of Titanium (H.-P. Nicolai and Chr. Liesner).10. Superplastic Forming and Diffusion Bonding of Titanium and Titanium Alloys (W. Beck).11. Forging of Titanium (G. Terlinde, et al.).12. Continuous Fiber Reinforced Titanium matrix Composites: Fabrication, Properties and Applications (C. Leyens, et al.).13. Titanium Alloys for Aerospace Applications (M. Peters, et al.).14. Production, Processing and Application of gamma(TiAl)-Based Alloys (H. Kestler and H. Clemens).15. Non-Aerospace Applications of Titanium and Titanium Alloys (M. Peters and C. Leyens).16. Titanium and its Alloys for Medical Applications (J. Breme, et al.).17. Titanium in Dentistry (J. Lindigkeit).18. Titanium in Automotive Production (O. Schauerte).19. Offshore Applications for Titanium Alloys (L. Lunde and M. Seiersten).Subject Index.

Abstract: The chapter discusses various methods used to treat titanium and titanium alloys for adhesive bonding. It is reported that both alkaline cleaning and phosphate-fluoride prebond treatments produce surfaces of good wettability, equal thickness and similar composition. Stabilized phosphate-fluoride process retards the conversion of anatase to rutile. It is also reported that the anodic process produces a porous oxide structure and is superior to the surface formed by the phosphate-fluoride process. Specific treatments for aluminum and aluminum alloys are presented in a process specification format including anodize process, Turco 5578, liquid hone/Pasa-Jell 107 process, dry hone/Pasa-Jell 107 process, alkaline peroxide process and stabilized phosphate-fluoride process. A study of the morphology and decomposition of the various surfaces revealed that different surface morphologies are obtained with the different treatments. The treatments were classified into three different groups. The Group I processes were characterized as producing surfaces which have thin oxide layers with little macro-roughness while Group II processes resulted in surfaces which had a high degree of macro-roughness. The Group III processes produced surfaces which were characterized by a primarily micro-rough porous oxide.

Abstract: Friction stir processing (FSP), developed based on the basic principles of friction stir welding (FSW), a solid-state joining process originally developed for aluminum alloys, is an emerging metalworking technique that can provide localized modification and control of microstructures in near-surface layers of processed metallic components. The FSP causes intense plastic deformation, material mixing, and thermal exposure, resulting in significant microstructural refinement, densification, and homogeneity of the processed zone. The FSP technique has been successfully used for producing the fine-grained structure and surface composite, modifying the microstructure of materials, and synthesizing the composite and intermetallic compound in situ. In this review article, the current state of the understanding and development of FSP is addressed.