PDF
Full
Outline
A 5B70 aluminum alloy sheet with ${1.5}\mathrm{\;{mm}}$ thickness is welded by tungsten inert gas (TIG) welding with 5B71 filler wire. The micro-structure evolution and refinement characteristics of the welded joints are investigated. The research results indicated that weld joints with excellent formation can be obtained by adopting reasonable welding parameters. The internal structure of the weld seam shows that the weld zone is mainly composed of equiaxed crystals forming a cast structure, the size of the grain structure is uneven, there are widely larger grains with a diameter of ${40}\sim {50\mu}\mathrm{m}$, as well as ultrafine grain areas with a diameter of about ${20\mu }\mathrm{m}$ which distributes in fine strips and small blocks. The area of the ultrafine grain region is obviously smaller than other areas. It mainly distributes in the direction parallel to the fusion line, with a few distributed on the weld surface. Sc and Zr were used as modificator to refine the grains. The ${\mathrm{{Al}}}_{3}\left({\mathrm{{Sc}},\mathrm{{Zr}}}\right)$ second phase particles are precipitated in the welding pool during solidification. The function of such particle is to form heterogeneous nucleation particles, reduce nucleation power and increase the number of crystal nuclei. The area where Sc elements are enriched had a higher degree of grain refinement. The “undercooling” zone is formed along the front of the solid-liquid boundary, which promotes the formation of equiaxed grains. It results in a higher degree of grain refinement, which size is only about one half of other zones.
PDF
414
197
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
关闭全屏
No. 86 Xueyuan South Road, Haidian District, Beijing
010-62199257
qkjq@cast.org.cn
Copyright © 2025 China Association for Science and Technology. All rights reserved. For all open access content, the relevant licensing terms apply.
Sponsored by the Office of the Leading Group for Cybersecurity and Informatization of CAST, and supported by Science and Technology Review Publishing House
