Full
Outline
K439B nickel-based alloy is a novel high-temperature material capable of operating at 800 ℃， which has been widely used in critical components such as combustion chamber housings for aerospace engines. However， the traditional casting process struggles to meet the high qualification rate requirement for high-precision forming of thin-walled complex components. In this study， laser powder bed fusion （LPBF） technology is used to process samples. By adjusting the laser power （140-220 W） and scanning speed （600-1400 mm/s）， and using characterization techniques including optical microscopy， scanning electron microscopy， and electron backscatter diffraction， the effects of process parameters of LPBF on the relative density and microstructure are analyzed. The processing window （laser power：160-220 W， scanning speed：1000-1200 mm/s） for manufacturing K439B superalloy via LPBF is summarized， and two process parameters （160 W-1000 mm/s and 220 W-1200 mm/s） within the window are selected to process samples for tensile tests at room-temperature and 800 ℃. The results show that irregular pores and Ti-C carbides are prone to form under the 160 W-1000 mm/s （volume energy density（VED） = 66.67 J/mm³） parameter. In contrast， the samples processed under 220 W-1200 mm/s （VED = 114.58 J/mm³） have a uniform microstructure without carbide， whose ultimate tensile strength at room temperature is over 1 GPa and elongation is over 25%. However， at 800 ℃， all LPBF samples exhibit brittleness （with an elongation after fracture of approximately 0.5%）， which is mainly attributed to the lack of γ' phases and dissolution of cellular substructures inside the grains.This study provides process guidance and theoretical support for the engineering application of LPBF fabricated K439B alloy.
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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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