Formation mechanism of non-equilibrium phase layer at impact welded interface of dissimilar metal joints

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K06742
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Composite materials/Surface and interface engineering
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Kumai Shinji 東京工業大学, 物質理工学院, 教授 (00178055)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 接合・溶接 / 構造・機能材料 / 異種金属接合 / 数値解析 / 衝撃圧接 / 非平衡相

Outline of Final Research Achievements

In the prsent study, the explosive weding process, a kind of impact welding process, was divided into five processes. The welding behavior was investigated by using the coupled numerical analyses combining three models.The wavy interface morphology formed at the joint interface and the location of intermediate layer (IML) reproduced by simulation showed a good quantitative agreement with the experimental results. The estimated cooling rate at the joint interface was also reasonable to explain the microstructure and the evolution of non-equilibrium phase after welding.
The newly devised simulation models in the present study were effective to reveal the formation mechanism of characteristic joint interface morphology and IML. This suggests that the control of the interface morphology, reduction of the amount of IML and non-equilibrium phase, and improvement of mechanical properties of the impact welded dissimilar metal joints can be achieved by using the simulation results.

Free Research Field

接合、鋳造、組織制御、力学的性質、疲労、破壊、軽金属

Academic Significance and Societal Importance of the Research Achievements

衝撃解析手法と熱解析手法をリンクさせることにより、実験的手法では再現できない異種金属衝撃圧接材の衝突点における両金属成分の分散（混合）挙動、衝撃圧接界面における圧力上昇と温度上昇、その後の熱拡散による冷却（温度低下）挙動をシミュレーションし、これを実際に得られた衝撃圧接界面組織と突き合わせることによって、世界に先駆けて非平衡相を含む中間層等、異種金属衝撃圧接界面に特有な組織の形成メカニズムを明らかにしている。よって、当該分野への学術的貢献は非常に大きい。さらに本研究によって、強度や信頼性に優れた異種金属接合材を作製するための指針が見出され、安心・安全な社会の構築に寄与するものとなっている。