A Study on convection in molten zone of aluminum alloy during Fe/Al resistance spot welding

伊與田 宗慶*; 松田 朋己*; 佐野 智一*; 茂田 正哉*; 菖蒲 敬久; 湯本 博勝*; Koyama, Takahisa*; Yamazaki, Hiroshi*; 仙波 泰徳*; 大橋 治彦*; et al.

Journal of Manufacturing Processes, 94, p.424 - 434, 2023/05

https://doi.org/10.1016/j.jmapro.2023.03.032

Aluminum alloys are increasingly being applied to automobile bodies to reduce the weight of automobiles. In joining steel materials and aluminum alloys using resistance spot welding (RSW), it is important to control the state of intermetallic compounds due to the temperature at the joining interface. In other words, in RSW of Fe/Al dissimilar materials, it is necessary to clarify the heating and cooling phenomena of the interface temperature during joining. Although the convection behavior of the molten aluminum alloy is thought to influence the temperature distribution at the joining interface, there are no studies that have directly observed this phenomenon. In this study, convection in molten zone of aluminum alloy during RSW of steel and aluminum alloy is discussed. Direct observations were attempted in order to clarify the convection behavior of the molten aluminum alloy in RSW of steel and aluminum alloy. The main feature of this experiment is that a real-scale test piece and an RSW apparatus used in actual production were used to observe convection during actual production. The observation experiments were conducted using synchrotron radiation X-ray at SPring-8. During welding, the specimens were irradiated with synchrotron radiation X-ray, and convection was observed from the behavior of tracer particles placed on the specimens. As a results, three types of convection were observed: radial outward convection from the center of the molten zone at the joining interface, convection from the edge of the molten zone toward its center, and weak circulating convection at the edge of the molten zone. And, small convection velocities were generated at the edge of the molten zone. Furthermore, the convection velocity inside the molten zone was calculated to be approximately 1.75 m/s. In addition, it was shown that there is a correlation between convection behavior and the shape of the molten zone.

革新的高温ガス炉燃料・黒鉛に関する技術開発計画(受託研究)

沢 和弘; 植田 祥平; 柴田 大受; 角田 淳弥; 大橋 準平; 栃尾 大輔

JAERI-Tech 2005-024, 34 Pages, 2005/03

JAERI-Tech-2005-024.pdf:2.15MB

第四世代(GEN-IV)原子炉システムの有力な候補となっている超高温ガス炉(VHTR)では、燃料は1520%FIMA,高速中性子照射量610m(E0.1MeV)においても健全性を保つ必要があるが、従来のSiC被覆燃料粒子では、このような厳しい条件下で健全性を保ったデータはない。原研で開発してきたZrC被覆燃料粒子は、SiC被覆燃料粒子よりも高温かつ高燃焼度下で健全性を維持できると期待されている。原研では、(1)従来よりも大型の被覆装置によるZrC蒸着技術の開発,(2)ZrC検査技術の開発,(3)ZrC被覆層の照射試験及び照射後試験を開始する。また、反応度投入試験を実施して被覆燃料粒子の破損機構を把握し、反応度事故時の燃料温度制限の緩和を目指す。VHTRでは、炉心の黒鉛構造物も高い中性子照射条件下で健全性を維持しなくてはならない。そこで、黒鉛構造物の超音波伝播特性や微小硬度計による圧子の押込み特性により、黒鉛構造物の機械的特性を非破壊的に評価できる技術を開発する。本報は、文部科学省からの受託研究として2004年11月から開始したこれらの研究開発の計画と2004年度の成果についてまとめたものである。