激光选区熔化成形AI-Mg-Sc合金与O态5A06板材TIG焊工艺研究

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Abstract：Aselective laser melting formedAl-Mg-Scallysheetand 5AO6with Oheat treatmentsheet with the thickness of 1 . 2 m m were welded by tungsten inert gas （TIG） welding with 5B71 filler wire. The microstructure evolution and refinement characteristics of the welded joints were investigated.The results showed that a large number of pores with the diameter of 0 . 2 m m distributed near the front surface of the weld zone and the fusion line ofthe SLMAl-Mg-Sc and 5AO6 with Oheat treatment sheet weld sample with appropriate TIG welding parameters. The number and size of pores and inclusions near the fusion line of SLMside were larger than thatof 5AO6 side and base metals in the welded joint.The microstructure of weld zone was equiaxed grains，which was optimized by the micro-alloying elements of Sc and Z r . The subcooled zone of molten pool was ultrafine grain region composed of the average finer grain with a diameter of about 2 0 μ m .Meanwhile， the other zones of molten pool mainly consisted of equiaxed grains with a diameter of 4 0～5 0 μ m . It was found that some concentrated pores， no shear lip and some

dimples were present on the surface of fracture sample.Furthermore，some strengthening phases were observed in the dimples.It was indicated that the fracture mode was brittle-ductile mixed.

Keywords： Al-Mg-Sc alloy; SLM; TIG; microstructure; grain

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以粉末床为主要技术特征的激光选区熔化（SelectiveLaserMelting，SLM）技术，是目前应用较广泛的金属3D打印技术，可以加工异形零件，并被许多国家应用到航空、航天领域中。（剩余6953字）