Effect of friction stir forming parameters on mechanical properties and plastic flow of material in the mechanical interlocking of optical fiber and SP-700 superplastic titanium alloy
Hamed Mofidi Tabatabaei, Takahiro Ohashi, Tadashi Nishiharadownload PDF
Abstract. The present study discusses the fluidity of titanium alloy during friction stir forming (FSF) and investigates the effect of process parameters on the mechanical properties of titanium alloy in the mechanical interlocking of optical fiber and SP-700 superplastic titanium alloy. In this study, a guide slit is provided in a titanium alloy plate, an optical fiber is placed inside the slit, and FSF is performed on the surface of the titanium alloy. By performing FSF, titanium softens and material plastically deforms inside the slit, which results in mechanically joining optical fiber and titanium alloy. Experimental results of evaluating the mechanical properties after FSF revealed that the hardness value of the material that flowed into the slit was significantly higher than that of the base material, which confirms that the stirring zone has flowed into the slit around the fiber. It was also confirmed that the temperature becomes unstable during the process for a travel speed of 50 mm/min or less, also above 800 mm/min. This resulted in insufficient material flow. As a result, inhomogeneous structures were confirmed. Tensile test results after FSF showed that the strength was lower than that of the base metal (67% to 55% of the base metal) for most process parameters. Although no significant changes in strength were observed by changing the travel speed, it was confirmed that the strength has an increasing tendency as the rotation speed increases, which is considered to be related to the grain refinement of the material. It was also concluded that the limitations in the present study such as insufficient material flow and reduced strength and also damage to the embedded optical fiber can be improved by pre-heating the workpiece and controlling the FSF process parameters which require further experiments and temperature measurements during FSF. In this study, the developed composite can give us hope for embedding FBG sensors inside high melting point alloys to simultaneously measure deformation, strain, pressure, and temperature and create new functional smart materials.
Friction Stir Welding, Friction Stir Forming, Titanium Alloy, Superplasticity, SP-700, Optical Fiber, Mechanical Interlock, Dissimilar Material Joining
Published online , 8 pages
Copyright © 2023 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Hamed Mofidi Tabatabaei, Takahiro Ohashi, Tadashi Nishihara, Effect of friction stir forming parameters on mechanical properties and plastic flow of material in the mechanical interlocking of optical fiber and SP-700 superplastic titanium alloy, Materials Research Proceedings, Vol. 32, pp 95-102, 2023
The article was published as article 10 of the book Superplasticity in Advanced Materials
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
 W.M. Thomas et al. “Friction Stir Welding”, International Patent Application No. PCT/GB92/ 02203.
 T. Nishihara, “Development of Friction Stir Forming”, Mater. Sci. Forum, 426-432 (2003) 2971-2978. https://doi.org/10.4028/www.scientific.net/MSF.426-432.2971
 Hamed Mofidi Tabatabaei, Takahiro Ohashi, Tadashi Nishihara, “Innovative Method of Embedding Optical Fiber inside Titanium Alloy”，Utilizing Friction Stir Forming, Key Engineering Materials, 934, pp. 67-73. https://doi.org/10.4028/p-683ks0
 H. M. Tabatabaei et al., “Friction Stir Forming for Mechanical Interlocking of Ultra-Thin Stainless Steel Strands and Aluminum Alloys”, Defect and Diffusion Forum, 382, pp.114-119, 2018. https://doi.org/10.4028/www.scientific.net/DDF.382.114
 Hamed Mofidi Tabatabaei, Tadashi Nishihara, Friction stir forming for mechanical interlocking of insulated copper wire and Zn-22Al superplastic alloy, Weld World, 61:47-55, December 2016. https://doi.org/10.1007/s40194-016-0406-9
 Hamed Mofidi Tabatabaei, Takahiro Hara, Tadashi Nishihara, Production of a Superplastic Vibration-Damping Steel Sheet Composite Using Friction Stir Forming, Materials Science Forum 838-839:574-580, January 2016. https://doi.org/10.4028/www.scientific.net/MSF.838-839.574
 Takahiro Ohashi, Tadashi Nishihara, Hamed Mofidi Tabatabaei, Mechanical Joining Utilizing Friction Stir Forming, Materials Science Forum, 1016:1058-1064, January 2021. https://doi.org/10.4028/www.scientific.net/MSF.1016.1058
 Takahiro Ohashi, Hamed Mofidi Tabatabaei, Tadashi Nishihara, Cylindrical extrusions on A5083 aluminum alloy plate fabricated by friction stir forming, AIP Conference Proceedings, 1896(1):080002, October 2017. https://doi.org/10.1063/1.5008082
 A. Ogawa, M. Niikura, C. Ouchi, K. Minikawa, and M. Yamada, “Development and Applications of Titanium Alloy SP-700 with High Formability,” Journal of Testing and Evaluation 24, no. 2 (1996): 100-109.
 Hall E.O., “The deformation and ageing of mild steel: III Discussion of results,” Proceedings of the Physical Society 64 (1951) 747-753. https://doi.org/10.1088/0370-1301/64/9/303
 Petch N.J., “The cleavage strength of polycrystals,” J. Iron and Steel Inst. 174 (1953) 25-28.