2005 Fiscal Year Final Research Report Summary
Weldability of aluminum alloy and steel alloy by means of friction stirring and its welding mechanism
| Project/Area Number |
16560631
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Material processing/treatments
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| Research Institution | Toyohashi University of Technology |
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Principal Investigator |
YASUI Toshiaki Toyohashi University of Technology, Faculty of Enginnering, Associate Professor, 工学部, 助教授 (10263229)
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| Co-Investigator(Kenkyū-buntansha) |
FUKUMOTO Masahiro Toyohashi University of Technology, Faculty of Engineering, Professor, 工学部, 教授 (80173368)
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| Project Period (FY) |
2004 – 2005
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| Keywords | Joining of dissimilar material / Friction Stir / FSW / Weld Interface / TEM observation / X-ray CT |
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| Research Abstract |
Weldability of aluminum alloy and steel alloy by friction stirring was evaluated, and its welding mechanism was investigated. Following results were obtained.
1) By optimizing the rotating speed and welding speed, aluminum and steel was welded without macroscopic defect in the welded joint.
2) Welded joints have heat affected zone (HAZ), and stir zone (SZ) in aluminum. The hardness of HAZ and SZ are lower than that of base aluminum. From the tensile test, the welded joints were fractured at the lowest hardness area in boundary between HAZ and SZ. The tensile strength and bending strength of welded joint decreased with increasing heat input and heat treatment.
3) Macroscopic defect in the welded joint deeply relate to the heat input during welding. At low heat input, interface cavity was mainly formed at the interface. While, bottom cavity was formed at the tool bottom at the higher heat input. By optimizing the heat input, there was no defect in the welded joints. However, preheating of specimen affected defect formation.
4) There was a reaction layer of several hundred nm in the weld interface. The material composition changed with heat input during welding.
5) During welding, steel on the weld interface was grinded and dispersed into the stir zone by plastic flow of aluminum. Its dispersed area depended on the heat input.
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