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Based on the hot-ended casing of K4169 superalloy as the research object, aiming at the defects such as liquid splashing, oscillation and entrained air in the linear filling process of traditional superalloy counter-gravity casting, particularly, considering the complex variable cross-section structure of the casing castings, the work explores the influence of pressurization speed on filling of such structure through hydraulic simulation experiments. The results reveal that for the variable cross-section structure, a lower pressurization speed leads to more stable liquid filling. Orthogonal experiments are conducted to ascertain the optimal filling process parameter of the casing model such as a pouring temperature of 1460 ℃, a shell temperature of 900 ℃ and an average pressurization speed of 4 kPa/s. Based on the casing model’s structure, linear and nonlinear filling pressure curves are designed, and both numerical simulations and experimental studies are performed to compare two filling methods. When comparing two filling processes with the same filling time, the nonlinear filling exhibits a 16.77% decrease in average gate speed compared to the linear filling, resulting in a more stable filling process and production of fewer overall defects in the thin wall areas of the casing. Casings filled using the linear method exhibit numerous crack defects across various regions, leading to a relatively high overall defect rate. In contrast, casings filled using the nonlinear method devoid of crack defects and contain only a few micro-pores. Non-destructive testing results also support the notion that casing castings filled by the nonlinear method have fewer defects, which validates that the nonlinear filling effectively reduces the type and quantity of defects in casing castings.
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| 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 |
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