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Tsutomu Tanaka

Bio: Tsutomu Tanaka is an academic researcher from Osaka Prefecture University. The author has contributed to research in topics: Superplasticity & Friction stir welding. The author has an hindex of 14, co-authored 44 publications receiving 873 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, the postweld properties of dissimilar friction stir welds of mild steel/A7075-T6 aluminum alloy were investigated and the joint strength increased with reduction in thickness of the intermetallic compound at the weld interface.

279 citations

Journal ArticleDOI
TL;DR: In this article, the relationship between the microstructure of the stir zone and the mechanical properties of FS-welded 5083 aluminum alloy was investigated, and it was indicated that the formability in FS-warmed 5083 Al alloy was improved by the refinement of grain size.
Abstract: Friction stir welding (FSW) has received a great deal of attention as a new solid-state welding technique. In the present study, the relationship between the microstructure of stir zone and the mechanical property of FS-welded 5083 aluminum alloy was investigated. The microstructures of the stir zones consisted of fine equiaxed grains at various FSW conditions in FS-welded 5083 Al alloy. However, the grain size of the stir zone decreased with the decrease in friction heat flow during FSW. The ductility in FS-welded 5083 Al alloy increased with the decrease in friction heat flow. It was indicated that the formability in FS-welded 5083 Al alloy was improved by the refinement of grain size of the stir zone.

215 citations

Journal ArticleDOI
TL;DR: In this article, the formation of intermetallic compounds (IMCs) during the friction stir welding (FSW) of aluminum and steel is problematic because these IMCs can reduce weld strength.
Abstract: The formation of intermetallic compounds (IMCs) during the friction stir welding (FSW) of aluminum and steel is problematic because these IMCs can reduce weld strength. In this study, the mechanism behind the observed rapid growth of IMCs during the dissimilar FSW of aluminum and steel was investigated. The temperature during welding was measured using K-type thermocouples, and the microstructures of cross sections of the welded materials were examined via scanning electron microscopy. Microstructural observations indicated that the growth of IMCs was not constant, but occurred in two rapid growth steps. The first phase of rapid IMC growth was observed immediately after the probe contacted the steel, while the second began in the region subjected to the large downward pressure of the tool shoulder on the steel plate. The measurements showed that the temperature underneath the tool shoulder was higher than that at the tool probe. Additionally, it was found that the two IMC growth steps and the growth rate could be expressed by an equation based on metallic diffusion and the measured temperatures. As the IMCs grew rapidly via contact between the steel plate and the tool probe or shoulder, it is necessary to control such contacts to inhibit IMC growth. This strategy and the proposed formula for predicting IMC growth rates could help improve the strength of welds during the fabrication of lightweight materials in the automotive and aerospace industries.

49 citations

Journal ArticleDOI
TL;DR: In this article, a maintenance-free seismic damperming system using superplastic Zn-Al alloy has been proposed for high-rise buildings, which has high ductility, low work hardening and no harmful metal to human health.

42 citations

Journal Article
TL;DR: In this article, the deformation behavior of Zn-22 mass%Al alloy including nanocrystalline structure produced with Thermo Mechanical Controlling Process (TMCP) technology has been characterized over a wide range of strain rates from 10 -6 to 10 -1 s -1 at temperatures from 273 to 473 K.
Abstract: The deformation behavior near room temperature in Zn-22 mass%Al alloy including nanocrystalline structure produced with Thermo Mechanical Controlling Process (TMCP) technology has been characterized over a wide range of strain rates from 10 -6 to 10 -1 s -1 at temperatures from 273 to 473 K. The microstructure of TMCP produced Zn-22 mass%Al alloy had both a random distribution of equiaxed Al-rich and Zn-rich phases with grain size of 1.3 μm and many nanocrystalline Zn particles in Al-rich phases. Since the flow stress in the deformation near room temperature was much larger than that in superplastic deformation and a maximum m value is only 0.3 (n = 3) at low strain rates below 10 -5 s -1 , the pure superplastic behavior may not be observed near room temperature. However it is noted that the large elongation of ∼ 200% was observed at 10 -5 s -1 . From microstructural observations of the specimens tested in the condition with the m value of 0.3 near room temperature, furthermore, it is considered that grain boundary sliding (GBS) is the dominant deformation process, and the specimen may be fractured by cavitation as well as the conventional superplastic materials. Therefore, it seems that the various factors contribute to the deformation flow at room temperature.

39 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the authors investigated the relationship between the processing parameters, the heat and plastic deformation produced and the resulting microstructure and mechanical properties in friction stir welding (FSW).

415 citations

Book ChapterDOI
TL;DR: The authors mimicking nature's bottom-up construction processes is one of the most promising directions in the development of robotic construction systems, which can be found in many applications, e.g.
Abstract: Successfully mimicking nature's bottom-up construction processes is one of the most promising directions.

410 citations

Journal ArticleDOI
TL;DR: In this article, a comprehensive understanding of the fundamentals of the microstructural evolution during FSW/P has been developed, including the mechanisms underlying the development of grain structures and textures, phases, phase transformations and precipitation.

390 citations

Journal ArticleDOI
TL;DR: In this paper, a review of the control strategies for back support, weld thinning, and keyhole defects in friction stir welding (FSW) is presented, which are basically divided into self-supported FSW, non-weld-thinning FSW and friction stir-based remanufacturing.

350 citations

Journal ArticleDOI
TL;DR: In this paper, the microstructures and mechanical properties of friction stir welded Al-alloys existing in the open literature are discussed in detail in order to highlight the correlations between weld parameters used during FSW and the micro-structures evolved in the weld region and thus mechanical properties.
Abstract: The diversity and never-ending desire for a better life standard result in a continuous development of the existing manufacturing technologies. In line with these developments in the existing production technologies the demand for more complex products increases, which also stimulates new approaches in production routes of such products, e.g., novel welding procedures. For instance, the friction stir welding (FSW) technology, developed for joining difficult-to-weld Al-alloys, has been implemented by industry in manufacturing of several products. There are also numerous attempts to apply this method to other materials beyond Al-alloys. However, the process has not yet been implemented by industry for joining these materials with the exception of some limited applications. The microstructures and mechanical properties of friction stir welded Al-alloys existing in the open literature will be discussed in detail in this review. The correlations between weld parameters used during FSW and the microstructures evolved in the weld region and thus mechanical properties of the joints produced will be highlighted. However, the modeling studies, material flow, texture formation and developments in tool design are out of the scope of this work as well as the other variants of this technology, such as friction stir spot welding (FSSW).

325 citations