| Project/Area Number |
09650789
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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 | Osaka University |
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Principal Investigator |
KURODA Toshio Joining and Welding Research Institute, Osaka University Associate Professor, 接合科学研究所, 助教授 (00107096)
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| Co-Investigator(Kenkyū-buntansha) |
KIKUCHI Yasushi Joining and Welding Research Institute, Professor, 接合科学研究所, 教授 (90005405)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1998: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1997: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Helium Ion Implantation / Austenitic Stainless Steel / Helium Bubble / Laser Welding / Weld Cracking / Numerical Calculation / Weldment / Transmission Electron Microscopy |
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| Research Abstract |
The formation of helium bubble in helium-doped SUS316L austenitic stainless steel weldments was investigated, by procedures in which the stainless steel was helium ion-implanted and then welded by YAG laser apparatus.
1. Helium ion implanting to the sample was carried out using 8MeV implantation apparatus.The samples (Heat (A)) were doped 2.45x 10^<19> atoms/m^2 at 6MeV and then lx 10^<19> atoms/m^2 at 5MeV, and the samples (Heat (B)) were doped to 9.0x10^<18> atoms/m^2 at 2.0MeV, 9.5x 10^<18> atoms /m^2 at 2.3MeV and 1.Ox 10^<19> atoms/m^2 at 2.6MeV.The helium concentration distribution was calculated using Monte Carlo Simulation and Gauss distribution method.
2. When laser power is low and rapid cooling conditions are satisfied, the volume of weld metal becomes small, and a mean helium concentration in the weld metal is increased.Very large helium bubbles more than 2 mum in diameter were present mainly near the bond region between the heat affected zone and the weld metal.
3. At high laser power, large helium bubbles are formed at the bond region, which lead to the occurrence of toe cracks, although the helium level of the weldment is decreased.Fine helium bubbles were observed at the dendrite cell boundaries in the weld metal by transmission electron microscopy.Helium bubbles were also observed at the crossing region between the first bead and the second bead in the cross bead repair welding.
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