Development of grain refinement method using recrystallization control during FSW

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05168
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 26050:Material processing and microstructure control-related
• Research Institution: National Institute for Materials Science
• Principal Investigator: NAGIRA Tomoya 国立研究開発法人物質・材料研究機構, 構造材料研究拠点, 主幹研究員 (00379124)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 摩擦攪拌接合 / 動的再結晶 / 積層欠陥エネルギー / 微細化機構

Outline of Final Research Achievements

In this study, grain refinement mechanisms during friction stir welding (FSW) for the FCC metals (Ag, Cu, and Cu-30Zn) with low-to-medium stacking fault energies were examined to develop the technique for the microstructural control from the aspect of discontinuous dynamic recrystallization and annealing twinning. It was found that the mechanism for grain structure development and grain size were determined by the ratio of peak temperature during FSW to the recrystallization temperature.

Free Research Field

溶接・接合

Academic Significance and Societal Importance of the Research Achievements

一般に構造物全体の特性は、主に最弱部である溶接部によって決まるため、本研究で対象とする摩擦攪拌接合は、溶接部の結晶粒微細化によって機械的特性の向上が期待できる有効な接合法である。得られた成果は、積層欠陥エネルギーが小から中程度の面心立方型の金属全般の組織制御指針の提案に繋がるため、広範な応用が期待できる。摩擦攪拌接合を利用した長寿命な構造体を作製するための接合技術の確立として大きな意義がある。