Element evaporation and as-cast structures of a new Ni-Co-based Superalloy affected by the second smelting power of electron beam smelting layered solidification technology
摘要
Compared with traditional smelting technology, the GH4068 alloy prepared by electron beam smelting layered solidification technology (EBS-LST) has a more uniform microstructure and lower microsegregation. To further optimize the as-cast microstructure of GH4068 alloy, the element volatilization, microstructure and microsegregation of GH4068 alloy prepared by EBS-LST of different second layer smelting powers were studied. The experimental results show that element volatilization gradually aggravates with the increase of smelting power, and the volatilization of Cr element is the most obvious. By analyzing the cross-sectional microstructures of ingots, it is found that the dendrite zone gradually reduces, while the cellular dendrite zone and cellular structure zone gradually increase with the increase of smelting power. The secondary dendrite arm spacing of ingots with the smelting power of 10 kW, 12 kW and 14 kW are 55.9 μm, 48.1 μm and 42.1 μm, respectively, which are all smaller than the ingot prepared by traditional duplex melting is 65.8 μm. The microsegregation of ingots in the dendrite zone is the most serious, and the size of precipitated phases in the cellular structure zone is the biggest. Therefore, considering the above experimental results, this paper believes that 12 kW is the better second layer smelting power.